U.S. patent application number 11/837435 was filed with the patent office on 2007-12-13 for semiconductor device, magnetic sensor, and magnetic sensor unit.
This patent application is currently assigned to YAMAHA CORPORATION. Invention is credited to Hiroshi Naito, Hideki Sato.
Application Number | 20070284684 11/837435 |
Document ID | / |
Family ID | 34863563 |
Filed Date | 2007-12-13 |
United States Patent
Application |
20070284684 |
Kind Code |
A1 |
Naito; Hiroshi ; et
al. |
December 13, 2007 |
SEMICONDUCTOR DEVICE, MAGNETIC SENSOR, AND MAGNETIC SENSOR UNIT
Abstract
A semiconductor device, comprising a semiconductor chip; a pad
electrode; an electrode portion; a wiring portion. An insulating
portion is formed from electrically insulating material, covering
the surface of the semiconductor chip and sealing the sensor
element, wiring portion and electrode portion, in a state which
exposes at least the electrode portion on the surface of the
semiconductor chip. The electrode portion is placed in a position
which does not overlap with the sensor element in the thickness
direction of the semiconductor chip.
Inventors: |
Naito; Hiroshi;
(Hamamatsu-shi, JP) ; Sato; Hideki;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
DICKSTEIN SHAPIRO LLP
1177 AVENUE OF THE AMERICAS (6TH AVENUE)
NEW YORK
NY
10036-2714
US
|
Assignee: |
YAMAHA CORPORATION
Hamamatsu-Shi
JP
|
Family ID: |
34863563 |
Appl. No.: |
11/837435 |
Filed: |
August 10, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11412923 |
Apr 28, 2006 |
7265430 |
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11837435 |
Aug 10, 2007 |
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11085573 |
Mar 22, 2005 |
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11837435 |
Aug 10, 2007 |
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Current U.S.
Class: |
257/421 ;
257/E23.021; 257/E43.001 |
Current CPC
Class: |
H01L 2224/1134 20130101;
H01L 2924/0001 20130101; H01L 2924/15159 20130101; H01L 24/06
20130101; H01L 24/02 20130101; H01L 2224/05008 20130101; G01R 33/02
20130101; H01L 2924/01078 20130101; H01L 2224/05001 20130101; H01L
2924/01006 20130101; H01L 24/14 20130101; H01L 2224/05166 20130101;
H01L 2924/15311 20130101; H01L 24/13 20130101; H01L 2224/05647
20130101; H01L 2224/05147 20130101; H01L 24/05 20130101; H01L
2924/01047 20130101; H01L 2924/01033 20130101; H01L 2224/14051
20130101; H01L 2924/014 20130101; H01L 2224/05026 20130101; G01R
33/09 20130101; H01L 23/3114 20130101; H01L 2224/02377 20130101;
H01L 2924/181 20130101; G01R 33/07 20130101; H01L 2224/0615
20130101; H01L 2224/1308 20130101; H01L 2224/16145 20130101; H01L
2924/01024 20130101; H01L 2224/05171 20130101; H01L 2924/14
20130101; H01L 2224/131 20130101; H01L 2924/00013 20130101; H01L
2924/01005 20130101; H01L 24/81 20130101; H01L 2224/05024 20130101;
H01L 24/16 20130101; H01L 2924/01079 20130101; H01L 2924/15153
20130101; H01L 2224/1403 20130101; H01L 2924/15151 20130101; H01L
2224/0603 20130101; H01L 2924/01029 20130101; H01L 2924/01022
20130101; H01L 2224/1308 20130101; H01L 2224/1134 20130101; H01L
2224/131 20130101; H01L 2924/014 20130101; H01L 2924/00013
20130101; H01L 2224/13099 20130101; H01L 2924/181 20130101; H01L
2924/00 20130101; H01L 2224/05647 20130101; H01L 2924/00014
20130101; H01L 2224/05147 20130101; H01L 2924/00014 20130101; H01L
2224/05166 20130101; H01L 2924/00014 20130101; H01L 2224/05171
20130101; H01L 2924/00014 20130101; H01L 2924/0001 20130101; H01L
2224/02 20130101 |
Class at
Publication: |
257/421 ;
257/E43.001 |
International
Class: |
H01L 43/00 20060101
H01L043/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2004 |
JP |
2004-087139 |
Mar 24, 2004 |
JP |
2004-087140 |
Claims
1. An azimuth sensor, comprising: a semiconductor chip on the
surface of which are formed integrated circuitry and a sensor
element; an electrode portion, positioned on the surface side of
said semiconductor chip adapted for electrically connecting said
semiconductor chip to external circuitry; and an insulating
portion, which covers the surface of said semiconductor chip and
seals said sensor element, and electrode portion, in a state which
exposes, at least, said electrode portion on the surface side of
said semiconductor chip; and wherein said electrode portion is
placed so that a stress is not applied to said sensor element.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a semiconductor device of the
surface-mountable type, such as chip-size packages or similar.
[0003] This invention further relates to a magnetic sensor and
magnetic sensor unit for measurement of the direction of a magnetic
field.
[0004] Priority is claimed on Japanese Patent Applications No.
2004-87139, filed Mar. 24, 2004, and No. 2004-87140, filed Mar. 24,
2004, the content of which is incorporated herein by reference.
[0005] 2. Description of the Related Art
[0006] Recent years have seen the appearance of LSI and other
semiconductor devices formed in dimensions substantially the same
as those of the semiconductor chip, such as chip-size packages
(hereafter called "CSPs") and similar, and capable of surface
mounting. Such technologies are attracting attention as mounting
technologies suitable for smaller and lighter electronic equipment
(see for example Japanese Patent Application, First Publication,
No. 9-107048).
[0007] In conventional surface-mounted semiconductor devices, a
plurality of bump electrodes for electrical connection to the
mounting board are arranged on the top side of the semiconductor
chip, having equal widths.
[0008] That is, as shown in FIG. 12, a plurality of virtual lattice
lines L21 are provided, extending in one direction (the X
direction) along the surface of the semiconductor chip, so as to
divide the surface of the semiconductor chip substantially
equally.
[0009] Further, similarly to the above, a plurality of virtual
lattice lines L22 are also provided, extending in a direction (the
Y direction) along the surface and orthogonal to the X direction,
so as to divide the surface of the semiconductor chip substantially
equally. A plurality of bump electrodes 97 are then arranged, with
one each at the intersections of these lattice lines L21, L22. Each
of the bump electrodes 97 is electrically connected to a pad
electrode 95 on the surface of the semiconductor chip by a wiring
layer provided on the surface of the semiconductor chip.
[0010] In order to reduce the size and weight of electronic
equipment, integration of semiconductor devices with functional
elements is also being employed. Such semiconductor devices are
provided with, for example, magnetic elements, Hall elements, piezo
elements, or other sensor elements having electrical functions,
arranged either together with or on the surface side of the
integrated circuits on the surface of the semiconductor chip. The
sensor element is placed in a prescribed position on the surface of
the semiconductor chip. That is, for example in a case in which
sensor elements are magnetic elements used for measurement of the
direction of an external magnetic field, when the semiconductor
device is mounted on a mounting board, the direction of the
magnetic field to be detected by each such magnetic element must be
confirmed, and the magnetic elements must be positioned at a
distance from each other so as not to be affected by other
elements; hence elements are arranged in the peripheral portions of
the surface of the semiconductor chip or in other predetermined
positions.
[0011] However, the sizes of the semiconductor chips of the above
conventional semiconductor devices are themselves tending to become
smaller with each passing year, so that wiring portions and bump
electrodes 97 are arranged in positions which overlap with sensor
elements 99 in the semiconductor chip thickness direction. In the
case of such a configuration, when the semiconductor device is
mounted on a mounting board, the stress of the bump electrodes 97
reaches the sensor elements 99. And in the case of such a
configuration, if there is bending in the region of the mounting
board on which the semiconductor device is mounted, with the
semiconductor device in the mounted state on the mounting board,
stress arising from the bending of the mounting board reaches the
bump electrodes 97 and, via posts and wiring layers, the sensor
elements 99. Moreover, when in such cases the semiconductor device
is mounted or operated, heating of the semiconductor device occurs,
and stress arises from thermal deformation of wiring layers at this
time, so that the stress on the wiring layers also reaches the
sensor elements 99.
[0012] That is, when a semiconductor device is mounted on a
mounting board, or when a semiconductor device is caused to
operate, the stress on the bump electrodes 97 and wiring layers
reaches the sensor elements 99, and so there is the problem that
the characteristics of the sensor elements 99 may fluctuate or be
degraded.
[0013] Further, when sensor elements 99 may affect a magnetic
field, as in the case of magnetic elements and Hall elements, if
bump electrodes 97, posts and wiring layers are placed in positions
overlapping with sensor elements 99, there is the problem that the
characteristics of the sensor elements 99 may fluctuate due to the
current-induced magnetic field arising due to current flowing in
posts and wiring layers.
[0014] In the prior art, magnetic sensors are provided which detect
magnetic fields for measurement of the direction in three
dimensions of an external magnetic field. As this type of magnetic
sensor, there are sensors in which a magnetosensitive portion
(magnetic sensor chip) is affixed to the surface of a
magnetosensing surface holding plate, and the magnetosensensing
surface holding plate and magnetosensitive portion (magnetic sensor
chip) are sealed with mold compound (see for example Japanese
Patent Application, First Publication No. 2002-156204).
[0015] Here, the magnetosensitive portion is configured so as to
detect magnetic components in a direction along the surface of the
magnetosensing surface holding plate. The magnetosensing surface
holding plate and magnetosensitive portion are covered by mold
compound in a state of contact with the surface of the circuit
board or other element supporting portion and inclined with respect
to the horizontal base. That is, in the state in which the magnetic
sensor is mounted on the element supporting portion, the plate and
the magnetosensitive portion are inclined with respect to the
surface of the element supporting portion. By providing two of the
magnetic sensors on the element supporting portion, such that the
directions of inclination of the two magnetosensitive portions with
respect to the surface of the element supporting portion are
different, the three-dimensional direction of an external magnetic
field can be measured.
[0016] However, in the case of a magnetic sensor with the above
configuration, the magnetosensitive portion is affixed to the
surface of the magnetosensing surface holding plate using silver
paste. At the time of this affixing, the silver paste must be
melted, so that the magnetosensitive portion and the magnetosensing
surface holding plate are heated to elevated temperatures.
[0017] However, in the case of the above magnetic sensor of the
prior art, because the magnetosensing surface holding plate and the
magnetosensitive portion are heated, when the magnetosensing
surface holding plate and the magnetosensitive portion comprise
materials with different thermal expansion coefficients, bending of
the magnetosensitive portion occurs due to the difference in
thermal expansion coefficients. And when bending occurs in the
magnetosensitive portion, there is the problem that the
characteristics of the magnetosensitive portion are degraded, and
the three-dimensional direction of an external magnetic field
cannot be measured accurately.
[0018] This invention was devised in light of the above-described
circumstances, and has as an object the provision of a
semiconductor device which can suppress fluctuations in and
degradation of the characteristics of a sensor element provided on
the surface of a semiconductor chip.
[0019] This invention was devised in light of the above-described
circumstances, and has as a further object the provision of a
magnetic sensor and magnetic sensor unit which prevent degradation
of the characteristics of a magnetic sensor chip, and enable
accurate measurement of the three-dimensional direction of a
magnetic field.
SUMMARY OF THE INVENTION
[0020] In order to resolve the above problems, in this invention
the following means are proposed.
[0021] The invention of first aspect proposes a semiconductor
device, comprising a semiconductor chip on the surface of which are
formed integrated circuitry and a sensor element, electrically
connected thereto; a pad electrode, formed on the surface side of
the semiconductor chip, and electrically connected to at least the
integrated circuitry; an electrode portion, positioned on the
surface side of the semiconductor chip, and electrically connecting
the semiconductor chip to external circuitry; a wiring portion,
electrically connecting the pad electrodes to the electrode
portion; and an insulating portion, formed from electrically
insulating material, which covers the surface of the semiconductor
chip and seals the sensor element, wiring portion, and electrode
portion, in a state which exposes, at least, the electrode portion
on the surface side of the semiconductor chip; and characterized in
that the electrode portion is arranged in a position which does not
overlap with the sensor element in the thickness direction of the
semiconductor chip.
[0022] Here, "sensor element" denotes an element having electrical
functions such as those of a magnetic element, a Hall element, a
piezo element, or similar.
[0023] By means of a semiconductor device of this invention, when
mounting the semiconductor device on a mounting board as an
external circuit, the semiconductor device is pressed against the
mounting surface of the mounting board in a state in which the
surface side of the semiconductor chip faces the mounting surface
of the mounting board. Here, the sensor element and electrode
portion are arranged in positions which do not overlap, and the
stress at the electrode portion due to the pressing which reaches
the sensor element can be reduced.
[0024] Further, even in cases in which there is bending of the
mounting surface of the mounting board when mounting the
semiconductor device, stress arising from the bending of the
mounting board which reaches the sensor element from the electrode
portion can be reduced.
[0025] Moreover, when causing the semiconductor device to operate,
an electromagnetic field arises due to the current flowing in the
electrode portion, but because the sensor element and electrode
portion are arranged at a distance, even when the sensor element is
affected by a magnetic field, as in the case of a magnetic element
or Hall element, the effect of the current-induced magnetic field
of the electrode portion on the sensor element can be reduced.
[0026] The invention of a second aspect proposes the semiconductor
device characterized in that the wiring portion is arranged in a
position which does not overlap with the sensor element in the
thickness direction of the semiconductor chip.
[0027] By means of a semiconductor device of this invention, when
there is bending of the mounting surface of the mounting board on
which the semiconductor device is mounted, even if stress arising
from the bending of the mounting board in the state in which the
semiconductor device 1 is mounted on the mounting surface reaches
the wiring portion from the electrode portion, the stress reaching
the sensor element can be reduced.
[0028] Further, when the semiconductor device is mounted on the
mounting board or when the semiconductor device is caused to
operate, the semiconductor device is heated and thermal deformation
of the wiring portion occurs; but even if stress on the wiring
portion occurs due to this thermal deformation, the stress of the
wiring portion which reaches the sensor element can be reduced.
[0029] Moreover, when the semiconductor device is caused to be
operated, a current-induced magnetic field occurs due to the
current flowing in the wiring portion; but because the sensor
element and the wiring portion do not overlap, even when the sensor
element is affected by a magnetic field, as in the case of a
magnetic element or Hall element, the effect of the current-induced
magnetic field of the wiring portion on the sensor element can be
reduced.
[0030] The invention of a third aspect proposes the semiconductor
device characterized in that a plurality of the above electrode
portions are provided, a plurality of first lattice lines are
supposed, extending in one direction on the surface of the
semiconductor chip, arranged at substantially equal intervals so as
to substantially equally divide the surface, a plurality of second
lattice lines are supposed, on the surface and intersecting with
the first lattice lines, arranged at substantially equal intervals,
and each of the points of intersection of the first lattice lines
and the second lattice lines are taken to be virtual placement
positions for the electrode portions; characterized in that, among
the electrode portions, one electrode portion which does not
overlap with the sensor element in the thickness direction is
placed in the virtual placement position, and the other electrode
portions among the above electrode portions are placed in positions
moved, from the virtual placement position, in a direction away
from the sensor element along first lattice lines or along second
lattice lines, and on the first lattice lines or on the second
lattice lines, the number of electrode portions placed between
adjacent lattice lines is one or less.
[0031] By means of a semiconductor device of this invention, the
distances between the other electrode portions shifted from the
virtual placement positions and the virtual placement positions are
shorter than the distances between virtual placement positions
which are adjacent along the first and second lattice lines
(distances between adjacent lattice lines), and by making the
number of electrode portions placed between adjacent lattice lines
equal to one or less, the distances between adjacent electrode
portions can be maintained to be equal to or greater than the
distances between the placement positions.
[0032] The invention of a fourth aspect proposes the semiconductor
device characterized in that a plurality of the above sensor
elements and a plurality of the above electrode portions are
provided, and the positional relationship between each of the
sensor elements and the electrode portions placed in the environs
of the sensor element, as well as the number of electrode portions
placed in the environs of each sensor element, are the same for all
of the sensor elements.
[0033] By means of a semiconductor device of this invention, even
if stress is applied to electrode portions at the time of mounting
on a mounting board, all of the sensor elements each receive stress
of the same magnitude from the electrode portions in the environs
thereof, so that the characteristics of all the sensor elements are
modified equally.
[0034] The invention of a fifth aspect proposes the semiconductor
device characterized in that one electrode portion placed in a
position adjacent to the above sensor element is formed to be small
compared with other electrode portions placed at a further distance
from the sensor element than the one electrode portion.
[0035] By means of a semiconductor device of this invention, by
forming one electrode portion adjacent to a sensor element to be
smaller than other electrode portions, the electrode portion can
easily be placed in a position which does not overlap with the
sensor element, without modifying the placement of the electrode
portion.
[0036] The invention of a sixth aspect proposes a semiconductor
device, comprising a semiconductor chip on the surface of which are
formed integrated circuitry and a sensor element, electrically
connected thereto; a pad electrode, formed on the surface side of
the semiconductor chip, and electrically connected to at least the
integrated circuitry; a plurality of electrode portions, positioned
on the surface side of the semiconductor chip, and electrically
connecting the semiconductor chip to external circuitry; a wiring
portion, electrically connecting the pad electrode to the electrode
portions; and an insulating portion, formed from electrically
insulating material, which covers the surface of the semiconductor
chip and seals the sensor element, wiring portion, and electrode
portions, in a state which exposes, at least, the electrode portion
on the surface side of the semiconductor chip; and characterized in
that the electrode portions comprise protruding portions which
protrude from the insulating portion in the thickness direction of
the semiconductor chip, and in that one protruding portion placed
adjacently to the sensor element has a smaller protrusion length
from the insulating portion compared with other protruding portions
placed at a distance from the sensor element.
[0037] By means of a semiconductor device of this invention, when
the semiconductor device is mounted on the mounting surface of a
mounting board, the other protruding portions make contact with the
mounting surface of the mounting board before the one protruding
portion. Consequently even if the electrode portion having the one
protruding portion is placed in a position overlapping the sensor
element in the semiconductor chip thickness direction, the stress
on the electrode portion having the one protruding portion can be
relaxed at the time of mounting of the semiconductor device on the
mounting board, and the stress of the electrode portion having the
one protruding portion which reaches the sensor element can also be
reduced.
[0038] The invention of a seventh aspect proposes a semiconductor
device, comprising a semiconductor chip on the surface of which are
formed integrated circuitry and a sensor element, electrically
connected thereto; a pad electrode, formed on the surface side of
the semiconductor chip, and electrically connected to at least the
integrated circuitry; a plurality of electrode portions, positioned
on the surface side of the semiconductor chip, and electrically
connecting the semiconductor chip to external circuitry; a wiring
portion, electrically connecting the pad electrode to the electrode
portions; and an insulating portion, formed from electrically
insulating material, which covers the surface of the semiconductor
chip and seals the sensor element, wiring portion, and electrode
portions, in a state which exposes, at least, the electrode portion
on the surface side of the semiconductor chip; and characterized in
that the electrode portions comprise protruding portions which
protrude from the insulating portion in the thickness direction of
the semiconductor chip, and in that one protruding portion placed
adjacently to the sensor element is formed from a conductive
material having a lower melting point compared with other
protruding portions placed at a distance from the sensor
element.
[0039] By means of a semiconductor device of this invention, when
the semiconductor device is mounted on the mounting surface of a
mounting board while applying heat to protruding portions, the one
protruding portion melts before the other protruding portions, so
that stress concentrates more on the electrode portions having the
other protruding portions than on the electrode portion having the
one protruding portion. Hence even if the electrode portion having
the one protruding portion is placed in a position which overlaps
the sensor element in the semiconductor chip thickness direction,
the stress on the electrode portion having the one protruding
portion can be relaxed, and the stress on this electrode portion
which reaches the sensor element can be reduced.
[0040] The invention of an eighth aspect proposes a semiconductor
device, comprising a semiconductor chip on the surface of which are
formed integrated circuitry and a sensor element, electrically
connected thereto; a pad electrode, formed on the surface side of
the semiconductor chip, and electrically connected to at least the
integrated circuitry; a plurality of electrode portions, positioned
on the surface side of the semiconductor chip, and electrically
connecting the semiconductor chip to external circuitry; a wiring
portion, electrically connecting the pad electrode to the electrode
portions; and an insulating portion, formed from electrically
insulating material, which covers the surface of the semiconductor
chip and seals the sensor element, wiring portion, and electrode
portions, in a state which exposes, at least, the electrode portion
on the surface side of the semiconductor chip; and characterized in
that the electrode portions comprise protruding portions which
protrude from the insulating portion in the thickness direction of
the semiconductor chip; in that the protruding portions comprise a
substantially spherical core formed from a conductive material and
a shell portion, covering the periphery of the core, and formed
from a conductive material with a melting point lower than that of
the above conductive material; in that the core of one protruding
portion placed adjacent to the sensor element is formed to be
smaller than the cores of other protruding portions placed at a
distance from the sensor element; and in that the diameters of the
shell portions of the one protruding portion and of the other
protruding portions are substantially equal.
[0041] By means of a semiconductor device of this invention, when
the semiconductor device is mounted on a mounting board with
protruding portions heated to a temperature which is lower than the
melting point of the conductive material from which the cores are
formed but higher than the melting point of the conductive material
from which the shell portions are formed, only the shell portions
of the protruding portions are melted, so that the cores of the
other protruding portions, with large diameters, make contact with
the mounting surface, while the core of the one protruding portion,
with a small diameter, does not make contact with the mounting
surface. At this time, stress is concentrated at the other
protruding portions, so that even if the electrode portion having
the one protruding portion is placed at a position overlapping with
the sensor element in the semiconductor chip thickness direction,
the stress on the electrode portion having the one protruding
portion can be relaxed, and the stress of the electrode portion
which reaches the sensor element can be reduced.
[0042] By means of the inventions of the first and second aspects,
even when a semiconductor device is mounted on a mounting board or
is caused to operate, stress at the electrode portions and wiring
portions which reaches the sensor element can be reduced, and
moreover the effect of current-induced magnetic fields of electrode
portions and wiring portions on the sensor element can also be
decreased, so that fluctuations and degradation of the
characteristics of the sensor element can be suppressed.
[0043] By means of the invention of a third aspect, the distances
between electrode portions can be kept equal to or greater than the
distances between virtual placement positions along first and
second lattice lines, so that even if electrode portions are
shifted from virtual placement positions, short-circuiting of
circuits across these electrode portions can be reliably
prevented.
[0044] By means of the invention of a fourth aspect, even if stress
is born by electrode portions at the time of mounting on a mounting
board, fluctuations due to the same stress can be cancelled out by
having the sensor elements form a bridge, so that the sensitivity
of sensor elements is stable regardless of stress.
[0045] By means of the invention of the fifth aspect, by forming
one electrode portion adjacent to a sensor element smaller than
other electrode portions, the electrode portion can easily be
placed in a position not overlapping with the sensor element,
without modifying the placement of the electrode portion.
[0046] By means of the inventions of the sixth to eighth aspects,
even if one electrode portion having a protruding portion is placed
in a position which overlaps a sensor element in the semiconductor
chip thickness direction, when the semiconductor device is mounted
on the mounting surface of the mounting board, the stress at the
one electrode portion comprising a protruding portion which reaches
the sensor element can be reduced, so that fluctuations and
degradation of the characteristics of the sensor element can be
suppressed.
[0047] The invention of a ninth aspect proposes a magnetic sensor,
comprising a magnetic sensor chip, formed substantially into a
sheet shape, which is sensitive to the magnetic component in at
least one direction of a magnetic field, and a plurality of
electrode portions, protruding from the surface of the magnetic
sensor chip, which electrically connect the magnetic sensor chip to
a substantially sheet-shaped circuit board, and characterized in
that the electrode portions are arranged in a row on the surface of
the magnetic sensor chip.
[0048] When mounting the magnetic sensor of this invention on a
circuit board, the plurality of electrode portions are brought into
contact with the surface of the circuit board, and the magnetic
sensor chip is electrically connected to the circuit board. At this
time, the plurality of electrode portions, arranged in a row,
protrude from the surface of the magnetic sensor chip, so that an
edge portion of the magnetic sensor chip is also in contact with
the surface of the circuit board. In this state, the magnetic
sensor chip is inclined with respect to the surface of the circuit
board, so that the direction of magnetic sensitivity of the
magnetic sensor chip is inclined with respect to the surface of the
circuit board, and a magnetic component in a direction intersecting
the surface of the circuit board can be detected by the magnetic
sensor chip.
[0049] Further, it is sufficient to fix at least the electrode
portions of the magnetic sensor to the surface of the circuit
board, so that the magnetic sensor can be mounted on the circuit
board with the magnetic sensor chip inclined, without heating of
the entire magnetic sensor chip.
[0050] The invention of a tenth aspect proposes a magnetic sensor,
comprising a magnetic sensor chip, formed substantially into a
sheet shape, which is sensitive to the magnetic component in at
least one direction of a magnetic field, and a plurality of
electrode portions, protruding from the surface of the magnetic
sensor chip, which electrically connect the magnetic sensor chip to
a substantially sheet-shaped circuit board, and characterized in
that the electrode portions are arranged in a plurality of parallel
rows on the surface of the magnetic sensor chip, and in that the
protrusion lengths of the electrode portions gradually become
shorter in the direction of arrangement of the plurality of
rows.
[0051] When mounting the magnetic sensor of this invention on a
circuit board, the plurality of electrode portions are brought into
contact with the surface of the circuit board, and the magnetic
sensor chip is electrically connected to the circuit board. In this
state, because the protrusion lengths of the electrode portions
gradually become shorter in the direction of arrangement of the
plurality of rows, the magnetic sensor chip is inclined with
respect to the surface of the circuit board. Hence the direction of
sensitivity of the magnetic sensor chip is inclined with respect to
the surface of the circuit board, and a magnetic component in a
direction intersecting the surface of the circuit board can be
detected.
[0052] Further, it is sufficient to fix the electrode portions of
the magnetic sensor to the surface of the circuit board, so that
the magnetic sensor can be mounted on the circuit board with the
magnetic sensor chip inclined, without heating of the entire
magnetic sensor chip.
[0053] Moreover, when the number of electrode portions provided on
the surface of the magnetic sensor chip is determined in advance,
by arranging the electrode portions separated into a plurality of
rows, the number of electrode portions placed in each row can be
reduced, so that the magnetic sensor chip can be formed in a
smaller size.
[0054] The invention of an eleventh aspect proposes a magnetic
sensor unit, comprising two of the magnetic sensors according to
the ninth or tenth aspect, and a circuit board on which are mounted
the magnetic sensors with the electrode portions caused to be in
contact with the board surface, and characterized in that the
magnetic sensor chip of at least one of the magnetic sensors is
sensitive to magnetic components of a magnetic field in two
directions, and that the magnetic sensors are placed on the circuit
board such that the direction of sensitivity of the other magnetic
sensor chip intersects the plane comprising the two directions of
sensitivity of the one magnetic sensor chip.
[0055] The invention of a twelfth aspect proposes a magnetic sensor
unit, comprising two of the magnetic sensors according to the ninth
or tenth aspect, and a circuit board on which are mounted the
magnetic sensors with the electrode portions caused to be in
contact with the board surface, and characterized in that the
magnetic sensor chip of at least one of the magnetic sensors is
sensitive to magnetic components of a magnetic field in two
directions, and that the two magnetic sensors are placed to at
least partially overlap on the circuit board such that the
direction of sensitivity of the other magnetic sensor chip
intersects the plane comprising the two directions of sensitivity
of the one magnetic sensor chip.
[0056] By means of a magnetic sensor unit of these inventions, two
magnetic sensors are prepared in advance, and a magnetic sensor
unit is configured such that the directions of sensitivity of the
magnetic sensor chips intersect. That is, one of the magnetic
sensor chips can detect magnetic components in any direction within
a plane comprising two sensitivity directions, and the other
magnetic sensor chip can detect magnetic components in a direction
intersecting the plane. Consequently three magnetic components in
three-dimensional space can be detected by the two magnetic sensor
chips, so that the direction of the magnetic field can be measured
as a vector in three-dimensional space.
[0057] When placing two magnetic sensors on a circuit board surface
to overlap, the mounting area of the two magnetic sensors on the
surface of the circuit board can be decreased, so that the magnetic
sensor unit can be made smaller.
[0058] The invention of a thirteen aspect proposes a magnetic
sensor unit, comprising a first magnetic sensor which is sensitive
to the magnetic components of a magnetic field in two directions, a
second magnetic sensor which is sensitive to the magnetic component
of a magnetic field in at least one direction, and a substantially
sheet-shaped circuit board on the surface of which the two magnetic
sensors are mounted, and characterized in that each of the magnetic
sensors comprises a magnetic sensor chip formed in substantially a
sheet shape, and a plurality of electrode portions, protruding from
the surface of the magnetic sensor chip, which are brought into
contact with the surface of the circuit board and are electrically
connected to the circuit board, and in that at least one of the
magnetic sensor chips is caused to be inclined with respect to the
rear surface of the circuit board, such that the direction of
sensitivity of the second magnetic sensor intersects the plane
comprising the two directions of sensitivity of the first magnetic
sensor, and moreover the sum of the height dimensions in the
circuit board thickness direction of the circuit board and of the
electrode portions is changed in portions.
[0059] By means of the magnetic sensor unit of this invention, the
first magnetic sensor can detect magnetic components in all
directions within a plane comprising the two sensitive directions,
and the second magnetic sensor can detect the magnetic component in
a direction intersecting this plane, so that by means of these two
magnetic sensors, three magnetic components in three-dimensional
space can be detected, and so the direction of a magnetic field can
be measured as a vector in three-dimensional space.
[0060] Further, the two magnetic sensors can be fixed onto the
circuit board with the electrode portions in contact with the
surface of the circuit board, so that each of the magnetic sensors
can be mounted on the circuit board with the two magnetic sensor
chips inclined relative to each other, without heating the entirety
of the magnetic sensor chips.
[0061] The invention of a fourteen aspect proposes the
semiconductor device characterized in that the surface of the
circuit board is formed in a staircase shape, and that the
electrode portions of at least one magnetic sensor are placed on
separate steps.
[0062] By means of the magnetic sensor unit of this invention,
because the heights from the rear face of the circuit board to the
tops of each of the steps are different, even if the protrusion
lengths of the plurality of electrode portions provided on the
surface of a magnetic sensor chip are the same, the magnetic sensor
chip can easily be inclined with respect to the surface of the
circuit board.
[0063] By means of the inventions of the ninth and tenth aspects,
when a magnetic sensor is mounted at an inclination on the circuit
board, the entirety of the magnetic sensor chip is not heated, so
that fluctuations and degradation of the characteristics of the
magnetic sensor chip can be prevented, and the direction of a
magnetic field can be correctly measured.
[0064] Further, by means of the invention of the tenth aspect, by
arranging the electrode portions divided into a plurality of rows,
the magnetic sensor chip can be formed in a small size, and the
size of the magnetic sensor can be reduced.
[0065] By means of the inventions of the eleventh and twelfth
aspects, a magnetic sensor is used which enabled prevention of
fluctuations and degradation of the characteristics of magnetic
sensor chips, so that the three-dimensional direction of a magnetic
field can be correctly measured.
[0066] Further, by means of the invention of the twelfth aspect,
the mounting area of two magnetic sensors on the surface of a
circuit board can be reduced, so that the size of the magnetic
sensor unit can be reduced.
[0067] By means of the invention of the thirteen aspect, when
mounting each magnetic sensor on the circuit board such that the
two magnetic sensor chips are inclined with respect to each other,
the entirety of the magnetic sensor chips is not heated, so that
fluctuations and degradation of the characteristics of the magnetic
sensor chips can be prevented, and the three-dimensional direction
of a magnetic field can be correctly measured.
[0068] By means of the invention of the fourteen aspect, the
heights from the rear surface of the circuit board to the top of
each step are different, so that the magnetic sensor chips can
easily be inclined with respect to the surface of the circuit
board.
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] FIG. 1 is a summary plane view showing the semiconductor
device of one aspect of the invention;
[0070] FIG. 2 is a cross-sectional view along arrow A-A of the
semiconductor device in FIG. 1;
[0071] FIG. 3 is a cross-sectional view along arrow B-B of the
semiconductor device in FIG. 1;
[0072] FIG. 4 shows schematically the method of manufacture of the
semiconductor device of FIG. 1;
[0073] FIG. 5 is a summary plane view showing the semiconductor
device of another aspect of the invention;
[0074] FIG. 6 is a cross-sectional view along arrow C-C of the
semiconductor device in FIG. 5;
[0075] FIG. 7 is a summary plane view showing the semiconductor
device of another aspect of the invention;
[0076] FIG. 8 is a summary plane view showing the semiconductor
device of another aspect of the invention;
[0077] FIG. 9 shows solder balls of the semiconductor device of
another aspect of the invention, wherein FIG. 9A is a
cross-sectional view of a solder ball placed in a position at a
distance from a thin film magnetic element, and FIG. 9B is a
cross-sectional view of a solder ball placed in a position
overlapping the thin film magnetic element;
[0078] FIG. 10 is a summary plane view showing the semiconductor
device of another aspect of the invention;
[0079] FIGS. 11A to 11C are enlarged cross-sectional views showing
electrode portions of the semiconductor device of another aspect of
the invention;
[0080] FIG. 12 is a summary plane view showing an example of a
semiconductor device of the prior art;
[0081] FIG. 13 is a summary plane view showing a magnetic sensor
unit of a second aspect of the invention;
[0082] FIG. 14 is a summary side view of the magnetic sensor unit
of FIG. 13;
[0083] FIG. 15 is a summary plane view showing the magnetic sensor
unit of another aspect of the invention;
[0084] FIG. 16 is a summary side view of the magnetic sensor unit
of FIG. 15;
[0085] FIG. 17 is a graph showing the relation between the
electrode portion position and the angle of inclination .theta. for
the magnetic sensor unit of FIG. 15;
[0086] FIG. 18 is a summary plane view showing the magnetic sensor
unit of another aspect of the invention;
[0087] FIG. 19 is a summary plane view showing the magnetic sensor
unit of another aspect of the invention;
[0088] FIG. 20 is a summary plane view showing the magnetic sensor
unit of another aspect of the invention;
[0089] FIG. 21 is a summary plane view showing the magnetic sensor
unit of another aspect of the invention;
[0090] FIG. 22 shows a magnetic sensor of another aspect of the
invention, wherein FIG. 22A is a summary side view, and FIG. 22B is
a summary side view showing the state of mounting on a circuit
board;
[0091] FIG. 23 is a summary plane view showing the magnetic sensor
unit of a third aspect of the invention;
[0092] FIG. 24 is a summary side view of the magnetic sensor unit
of FIG. 23;
[0093] FIG. 25 is a summary side view showing the magnetic sensor
unit of another aspect of the invention;
[0094] FIG. 26 shows a magnetic sensor of another aspect of the
invention, wherein FIG. 26A is a summary side view, and FIG. 26B is
a summary side view showing the state of mounting on a circuit
board;
[0095] FIG. 27 is a summary side view showing the magnetic sensor
unit of another aspect of the invention; and,
[0096] FIG. 28 is a summary side view showing the magnetic sensor
unit of another aspect of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0097] FIG. 1 to FIG. 3 show one aspect of the invention; the
semiconductor device of this aspect is one type of wafer-level CSP
(hereafter called a "WLCSP"), with electrodes for connection to the
external circuitry of the mounting board provided at positions
which do not protrude from the main face of the semiconductor chip
on which the integrated circuits are formed. As shown in FIG. 1 and
FIG. 2, this semiconductor device 1 comprises a semiconductor chip
3 in a sheet shape, formed into substantially a rectangular shape
in plane view; a plurality of thin film magnetic elements 5,
provided on the main face (surface) of the semiconductor chip 3;
electrode portions 7, placed on the side of the main face 3a of the
semiconductor chip 3, for connection of the semiconductor chip 3 to
external circuitry; wiring portions 9 for electrical
interconnection of the integrated circuits (not shown) of the
semiconductor chip 3 and the electrode portions 7; and an
insulating portion 11 which covers the surface 3a of the
semiconductor chip 3 in a state which exposes the electrode
portions 7 on the side of the main face 3a of the semiconductor
chip 3, and which seals the thin film magnetic elements 5, wiring
portions 9, and electrode portions 7.
[0098] The thin film magnetic elements 5 are formed as a thin film,
and measure the sense and magnitude of an external magnetic field.
Four such thin film magnetic elements 5 are placed on the periphery
of the main face 3a of the semiconductor chip 3. Each of the thin
film magnetic elements 5 is sensitive to the magnetic component of
an external magnetic field in one direction (in the X-axis
direction or in the Y-axis direction), and is placed such that the
direction of sensitivity is along the main face 3a of the
semiconductor chip 3. These thin film magnetic elements 5 are each
placed adjacent to one edge of the main face 3a of the
semiconductor chip 3, at a distance from each other. Pairs of
opposing thin film magnetic elements 5, 5 are configured so as to
detect the magnetic component in the same direction, to improve the
reliability of detection of an external magnetic field.
[0099] As shown in FIG. 1 and FIG. 3, the semiconductor chip 3
comprises a substrate 13, of rectangular shape in plane view, on
the surface 13a of which is formed integrated circuitry; a
plurality of (in the example shown, eight) pad electrodes 15,
formed on the surface 13a of the substrate 13; and a first
passivation film 17 provided on the surface 13a of the substrate
13, avoiding the pad electrodes 15. The pad electrodes 15
electrically connect the electrode portions 7 and the thin film
magnetic elements 5, and are placed on the periphery of the surface
13a of the substrate 13.
[0100] The first passivation film 17 is formed by layering on the
surface 13a of the substrate 13, in order, a thin film of silicon
dioxide (SiO.sub.2) and a thin film of silicon nitride (SiN),
avoiding the pad electrodes 15. The first passivation film 17 has
high heat resistance and is electrically insulating. The surface of
the first passivation film 17 constitutes the main face 3a of the
semiconductor chip 3.
[0101] The insulating portion 11 is obtained by layering in order
on the main face 3a of the semiconductor chip 3 a second
passivation film 19, a protective film 21, and a resin mold portion
23; this second passivation film 19, protective film 21, and resin
mold portion 23 are each formed from electrically insulating
materials.
[0102] The second passivation film 19, like the first passivation
film 17, is formed by layering in order, from the main face 3a of
the semiconductor chip 3, a thin film of silicon dioxide
(SiO.sub.2) and a thin film of silicon nitride (SiN), formed so as
to cover the first passivation film 17 while avoiding the pad
electrodes 15 used for electrical connection to the wiring portions
9. The thin film magnetic elements 5 are covered by this second
passivation film 19.
[0103] The protective film 21 is formed from polyimide (PI), and is
formed so as to cover the surface 19a of the second passivation
film 19a and the side wall faces of the groove portion 22
demarcated by the pad electrodes 15 and the first and second
passivation films 17, 19.
[0104] The resin mold portion 23 covers the surface 21a of the
protective film 21 and main face 3a of the semiconductor chip 3,
and in addition is formed so as to seal the post of the electrode
portions 7, described below, and the wiring portions 9. The resin
mold portion 23 is formed from resin material with a lower hardness
than the electrode portions 7 and wiring portions 9, and is formed
into a substantially rectangular shape in plane view, similarly to
the magnetic sensor chip 3.
[0105] The wiring portions 9 fill the groove portions 24 demarcated
by the pad electrodes 15 and protective film 19, and in addition
are formed to extend from the aperture of the groove portion 24
between the protective film 21 and the resin mold portion 23 of the
insulating portion 11, to the lower edge of the posts of the
electrode portions 7, described below. The wiring portions 9 are
formed by layering in order, from the surface 21a of the protective
film 21, of under-barrier metal 25 (hereafter "UBM") and the wiring
layer 27. The UBM 25 is formed from titanium (Ti) or chromium (Cr),
whereas the wiring layer 27 is formed from copper (Cu).
[0106] The UBM 25 is formed to be sufficiently thinner than the
wiring layer 27. That is, the thickness of the UBM 25 is for
example 0.18 .mu.m, whereas the thickness of the wiring layer 27 is
0.60 .mu.m.
[0107] Wiring portions 9 configured as described above are formed
in positions which do not overlap, in the thickness direction of
the semiconductor chip 3, with the thin film magnetic elements
5.
[0108] Each of the electrode portions 7 comprises a substantially
cylindrical post 29, extending from the surface 9a of the wiring
portion 9 to the surface 23a of the resin mold portion 23, and a
solder ball 31, mounted on the top end of the post 29, and
protruding from the surface 23a of the resin mold portion 23. The
post 29 is formed from copper, and the top end face 29a thereof is
formed in substantially the same plane as the surface 23a of the
resin mold portion 23. The solder ball 31 is solder material formed
into a substantially spherical shape.
[0109] A plurality of electrode portions 7 are placed at prescribed
positions which do not overlap, in the thickness direction of the
semiconductor chip 3, with thin film magnetic elements 5. That is,
three first lattice lines L1 to L3 extending in the X-axis
direction, as well as three second lattice lines L4 to L6 extending
in the Y-axis direction, so as to substantially equally divide the
main face 3a of the semiconductor chip 3 and the surface 23a of the
resin mold portion 23, are supposed to be arranged at equal
intervals.
[0110] The distances between the points of intersection (virtual
placement positions) P1 to P9 along the lattice lines L1 to L6 are
distances sufficient that no short-circuits occur between adjacent
electrode portions 7 in the state in which electrode portions are
placed at each of the points of intersection.
[0111] Among the three lattice lines placed and arranged at equal
intervals in each direction, the lines in the center which are the
first lattice line L2 and the second lattice line L5 are placed so
as to pass through thin film magnetic elements 5.
[0112] One each of the electrode portions 7 are placed at first
points of intersection P1 to P4, at which the first lattice lines
L1, L3 and the second lattice lines L4, L6 intersect. These first
points of intersection P1 to P4 are positioned at a distance from
the thin film magnetic elements 5.
[0113] Electrode portions 7 are placed at positions shifted from
the second points of intersection P5, P6 of the first lattice line
L2 with the second lattice lines L4, L6 along the first lattice
line L2 toward the fourth point of intersection P9 at which the
first lattice line L2 intersects the second lattice line L5. And,
electrode portions 7 are placed at positions shifted from the third
points of intersection P7, P8 of the first lattice lines L1, L3 and
the second lattice line L5 toward the fourth point of intersection
P9 along the second lattice line L5, so as to increase the distance
from the thin film magnetic sensors 5.
[0114] This is because the second points of intersection P5, P6 and
the third points of intersection P7, P8 are adjacent to the thin
film magnetic sensors 5, and if electrode portions were placed at
the second points of intersection P5, P6 and the third points of
intersection P7, P8, the electrode portions 7 would overlap with
the thin film magnetic elements 5 in the thickness direction of the
semiconductor chip 3.
[0115] As a result, the electrode portions 7 are placed in
positions which do not overlap with thin film magnetic elements 5
in the thickness direction of the semiconductor chip 3.
[0116] The above-described positions which do not overlap with thin
film magnetic elements 5 are in a positional relationship such that
the figures of the thin film magnetic elements 5 projected onto a
plane the normal to which is the mounting direction or the loading
direction, and the figures in the contact plane of solder balls 31
in contact with the top end faces 29a of posts 29 or with the
surfaces 23a of resin mold portions 23, or the figures of the
electrode portions 7, do not overlap at least partially.
[0117] In the case of this embodiment, the thickness direction of
the semiconductor chip 3 is the above mounting direction and
loading direction, so that when projecting figures onto a plane the
normal to which is substantially the thickness direction, each of
the above-described figures exists independently, and need only be
in a state in which there is no interference. Here, the mounting
direction signifies the direction in which a load is applied when
mounting the semiconductor device 1 on a mounting board, and the
load direction signifies the direction in which a load is applied
after mounting the semiconductor device 1 on a mounting moard.
[0118] These electrode portions 7 are placed such that the
positional relationships between each of the thin film magnetic
elements and the electrode portions 7 placed in the environs of the
thin film magnetic elements 5, and the number of electrode portions
7 placed in the environs of each thin film magnetic element 5, are
the same for all thin film magnetic elements 5. That is, three
electrode portions 7 are placed in the environs of each of the thin
film magnetic elements 5. Three electrode portions 7 are placed in
the same positions, with reference to the placement positions of
each of the thin film magnetic elements 5.
[0119] A method of manufacture of a semiconductor device 1
configured as described above is here explained.
[0120] First, four thin film magnetic elements 5 are placed at
prescribed positions of the main face 3a of the semiconductor chip
3, and as shown in FIG. 4, a second passivation film 19 is formed
on the main face 3a of the semiconductor chip 3, avoiding the pad
electrodes 15. At this time, the thin film magnetic elements 5 are
also covered by the second passivation film 19.
[0121] Next, a protective film 21 is formed on the surface 19a of
the second passivation film 19 and on the side wall faces of the
groove portion 22, and a thin film UBM 25 is formed on the surface
21a of the protective film 21 and on the wide wall faces and bottom
wall face of the groove portion 24.
[0122] Then, a first resist layer 41 is formed on the surface 25a
of the UBM 25, excluding the portions where the wiring layer 27 is
to be formed. This region of formation of the first resist layer 41
comprises a region of overlap, in the thickness direction of the
semiconductor chip 3, with the thin film magnetic elements 5. Then,
portions in which the first resist layer 41 is not formed, that is,
portions in which the UBM 25 is exposed are buried with copper to
form the wiring layer 27. After this, the first resist layer 41 is
removed.
[0123] Then, a second resist layer 43 is formed on the surfaces
27a, 25a of the wiring layer 27, excluding portions where posts 29
are to be formed, and of the UBM 25. In this state, only a portion
of the surface 27a of the wiring layer 27 is exposed. The portion
in which the second resist layer 43 is not formed, that is, the
portion in which the wiring layer 27 is exposed, is then buried
with copper to form posts 29. After formation of the wiring layer
27 and posts 29, the second resist layer 43 is removed, and the UBM
25 not covered by the wiring layer 27 is removed by etching.
[0124] Finally, the wiring portion 9 and posts 29 are sealed with a
resin material so as to cover the surface 21a of the protective
film 21 and expose the top end faces 29a of the posts 29, and by
depositing solder balls 31 onto the top end faces 29a of the posts
29, manufacture of the semiconductor device 1 is completed.
[0125] When mounting the semiconductor device 1 in the mounting
surface of a mounting board, with the surface 23a of the resin mold
portion 23 opposing the mounting surface, the semiconductor device
1 is pressed against the mounting surface while heating the solder
balls 31. As shown in FIG. 1 and FIG. 2, the thin film magnetic
elements 5 and the electrode portions 9 and wiring portions 9 are
placed in positions which do not overlap, so that stress applied to
electrode portions 7 by the above pressing which reaches the thin
film magnetic elements can be reduced.
[0126] When there is bending in the mounting surface of the
mounting substrate, in the state with the semiconductor device 1
mounted on the mounting surface, even if stress arising from the
bending reaches the wiring portions 9 from the electrode portions
7, the stress reaching the thin film magnetic elements 5 as well
can be reduced.
[0127] When causing the semiconductor device 1 to operate, a
current-induced magnetic field arises due to the currents flowing
in the electrode portions 7 and wiring portions 9, but because the
thin film magnetic elements 5 are placed in positions which do not
overlap with the electrode portions 7 or wiring portions 9, the
effect of the current-induced magnetic field of the electrode
portions 7 and wiring portions 9 on the thin film magnetic elements
5 can be reduced.
[0128] Further, when mounting the semiconductor device 1 on a
mounting substrate or causing the semiconductor device 1 to
operate, the semiconductor device 1 is heated, and thermal
deformation of wiring portions 9 occurs; but even if stress arises
in the wiring portions 9 due to this thermal deformation, the
stress arising from the thermal deformation which reaches the thin
film magnetic elements 5 can be reduced.
[0129] By means of the above semiconductor device 1, even when the
semiconductor device 1 is mounted on a mounting substrate or caused
to operate, stress in the electrode portions 7 and wiring portions
9 which reaches the thin film magnetic elements 5 can be reduced,
and the effect of current-induced magnetic fields of the electrode
portions 7 and wiring portions 9 on the thin film magnetic elements
5 can be decreased, so that fluctuations and degradation of the
characteristics of the thin film magnetic elements 5 can be
suppressed.
[0130] The distances from electrode portions 7 shifted from the
second and third points of intersection P5 to P8 along the lattice
lines L2 and L5 so as to increase the distance from thin film
magnetic elements 5 to the fourth point of intersection) 9 is made
shorter than the distances between the adjacent points of
intersection P1 to P9 along the lattice lines L1 to L6 (distances
between adjacent lattice lines), and electrode portions 7 are
completely comprised within the lattice lines; because the number
of electrode portions 7 positioned between adjacent lattice lines
is one or fewer, no electrode portion 7 is placed at the fourth
point of intersection P9, so that the distances between adjacent
electrode portions 7 can be kept equal to or greater than the
distances between the points of intersection P1 to P9. Hence even
if the electrode portions 7 are shifted from the second and third
points of intersection P5 to P8, short-circuits between these
electrode portions 7 can be reliably prevented.
[0131] By making the positional relationships between each of the
thin film magnetic elements 5 and the electrode portions 7 placed
in the environs of the thin film magnetic elements 5, and the
number of electrode portions 7 placed in the environs of each of
the thin film magnetic elements 5, the same for all thin film
magnetic elements 5, even if stress is applied to electrode
portions 7 at the time of mounting of the semiconductor device 1 on
the mounting board, fluctuations due to the same stress can be made
to cancel by having the thin film magnetic elements 5 form a
bridge, so that the sensitivity of the thin film magnetic elements
5 is stable regardless of the stress.
[0132] In the above aspect, one electrode portion 7 is placed in
each of the positions shifted from the second and third points of
intersection P5 to P8 adjacent to thin film magnetic elements 5;
however, the configuration is not limited to this, and it is
sufficient to place electrode portions in positions which, at
least, do not overlap with thin film magnetic elements 5 in the
thickness direction of the semiconductor chip 3. That is, as for
example shown in FIG. 5, electrode portions 7 may be placed in the
second and third points of intersection P5 to P8 adjacent to thin
film magnetic elements 5, forming each of the electrode portions 7
in a size such that there is no overlap in the thickness direction.
In the case of this configuration, electrode portions 7 can be
placed at all of the points of intersection P1 to P9.
[0133] In the case of the above configuration, as shown in FIG. 6,
the solder balls 31 of some electrode portions 7, positioned
adjacent to thin film magnetic elements 5, are smaller in diameter
than the other solder balls 31 of electrode portions 7 positioned
at a distance from the thin film magnetic elements 5. That is, the
protrusion lengths of certain solder balls 31 protruding from the
surface 23a of the resin mold portion 23 are shorter than those of
the other solder balls 31. Consequently when mounting the
semiconductor device 51 onto the mounting surface of the mounting
board while heating the solder balls 31, the other solder balls 31
make contact with the mounting surface of the mounting board before
the certain solder balls 31. Hence when mounting the semiconductor
device 51 on the mounting board, the stress at electrode portions 7
having the certain solder balls 31 is relaxed, and the stress at
these electrode portions 7 which reaches the thin film magnetic
elements 5 can be further reduced.
[0134] In the above configuration, the shape of the solder balls 31
is not limited to a spherical shape; by providing protruding
portions which at least protrude from the surface 23a of the resin
mold portion 23, and by making the protrusion lengths of certain
protruding portions positioned adjacent to thin film magnetic
elements 5 shorter than those of other protruding portions
positioned at a distance from the thin film magnetic elements 5, a
similar advantageous result can be obtained.
[0135] As shown in FIG. 7, when the number of electrode portions 7
is sufficiently great that, with the semiconductor device 61
mounted on the mounting board, the stress born by each of the
electrode portions 7 is equal to or less than a prescribed value, a
smaller number of electrode portions 7 may be placed than there are
points of intersection of the first lattice lines L7 to L11 with
the second lattice lines L12 to L16. Hence this semiconductor
device 61 may be configured with electrode portions 7 placed
neither to overlap thin film magnetic elements 5 nor placed at
adjacent points of intersection.
[0136] Thin film magnetic elements 5 are provided on the
semiconductor devices 1, 51, 61, but the device configuration is
not limited to this, and Hall elements, piezo elements, or, at
least, sensor elements having electrical functions, may be provided
on the device.
[0137] The electrode portions 7 are described as having been placed
in positions which do not overlap with sensor elements in the
thickness direction of the semiconductor chip 3; but when the
sensor elements are not affected by the current-induced magnetic
fields of the electrode portions 7 or wiring portions 9, this
configuration is not necessary, and it is sufficient that the
stress on the electrode portions 7 which reaches the sensor
elements be reduced. That is, as for example shown in FIG. 8,
certain solder balls 31a of electrode portions 7 placed at
positions which overlap with sensor elements 45 may be formed from
a conductive material with a lower melting point than the other
solder balls 31b of electrode portions 7 placed at a distance from
the sensor elements 45.
[0138] In the case of this configuration, when mounting the
semiconductor device on the mounting surface of the mounting
substrate while heating the solder balls 31a and 31b, the certain
solder balls 31a melt before the other solder balls 31b, so that
stress is concentrated on the electrode portions 7 having the other
solder balls 31b, rather than on the electrode portions 7 having
the certain solder balls 31a. Hence even if electrode portions 7
are placed at positions overlapping with sensor elements 45, the
stress on the electrode portions 7 having certain solder balls 31a
can be relaxed, and the stress at these electrode portions 7 which
reaches the sensor elements 45 can be reduced.
[0139] Further, as shown in FIG. 9A and FIG. 9B, when the solder
balls 31 comprise a substantially spherical core 47 formed from
conductive material and a shell portion 49 formed from a conductive
material with melting point lower than the conductive material of
the core, and covering the core 47, the diameters of the cores 47
of certain solder balls 31a placed adjacent to sensor elements 45
may be formed smaller than the cores 47 of the other solder balls
31b, and moreover the shell portions 49 of the certain solder balls
31a and of the other solder balls 31b may be formed to have
substantially the same diameter.
[0140] In the case of such a configuration, when the semiconductor
device is mounted on the mounting substrate while heating the
solder balls 31 to a temperature lower than the melting point of
the conductive material from which the cores 47 are formed, but
higher than the melting point of the conductive material from which
the shell portions 49 are formed, only the shell portions 49 of the
solder balls 31 are melted. Consequently the cores 47 of the other
solder balls 31b with larger diameters make contact with the
mounting surface of the mounting board, and the cores 47 of the
certain solder balls 31a with smaller diameters do not make contact
with the mounting surface. At this time, stress is concentrated at
the other solder balls 31b, so that even if the electrode portions
7 having the certain solder balls 31a are placed at positions
overlapping sensor elements 45, the stress at the electrode
portions 7 having the certain solder balls 31a can be relaxed, and
so the stress at the electrode portions 7 which reaches the sensor
elements 45 can be reduced.
[0141] Further, the pad electrodes 15 of the semiconductor chip 3
were placed on the periphery of the surface 13a of the substrate
13; but configurations are not limited thereto, and as for example
shown in FIG. 10, pad electrodes may be placed in the center
portion of the surface 13a of the substrate 13.
[0142] In the case of a semiconductor device 81 with the above
configuration, by placing electrode portions 7 on the outside of
these pad electrodes 15, the distances of the wiring portions 9
connecting pad electrodes 15 and electrode portions 7 can be set
shorter, so that the semiconductor device 81 can be made to operate
under low power.
[0143] Further, the sensor elements 45 are placed on the periphery
of the main face 3a of the semiconductor chip 3, positioned on the
outside of the electrode portions 7, so that the electrode portions
9 can be placed further from the positions of the sensor elements
45.
[0144] Hence stress at electrode portions 7 and wiring portions 9
which reaches thin film magnetic elements 5 can be further reduced,
and in addition the effect on thin film magnetic elements 5 of the
current-induced magnetic fields of the electrode portions 7 and
wiring portions 9 can be further decreased, so that fluctuation and
degradation of the characteristics of thin film magnetic elements 5
can be reliably suppressed.
[0145] In the above, electrode portions 7 comprised spherical
solder balls 31, but other configurations are possible; for
example, as shown in FIGS. 11A to 11C, a protruding portion
protruding at least from the surface 23a of the resin mold portion
23 may be comprised. That is, as for example shown in FIGS. 11A and
11B, protruding portions 53 which protrude from the resin mold
portion 23 may be formed integrally with posts 54.
[0146] These protruding portions 53 may for example be formed by
plating or by screen printing to apply a copper paste. And as shown
in FIG. 11C, after forming the posts 29 and resin mold portion 23,
resist may be patterned and plating used to form protruding
portions 55 with a substantially rectangular shape in
cross-sectional view.
[0147] In the above configurations, electrode portions 7 comprise
posts 29 or 54 and solder balls 31 or protruding portions 53, but
electrode portions 7 may also comprise only posts 29 or 54. In the
case of such a configuration, when mounting the semiconductor
device on a mounting board, the posts 29, 54 are electrically
connected with the circuitry of the mounting board using separately
supplied solder.
[0148] FIG. 13 and FIG. 14 show a second aspect of the invention;
the magnetic sensor unit of this aspect measures the sense and
magnitude of an external magnetic field. As shown in FIG. 13 and
FIG. 14, the magnetic sensor unit 101 comprises two magnetic
sensors 102 and 103, and a circuit board 105 on the surface 105a of
which the two magnetic sensors 102, 103 are mounted. The circuit
board 105 is formed in substantially sheet shape, with the surface
105a and rear surface 105b thereof substantially parallel. On the
rear surface 105b of the circuit board 105 are provided terminals
(not shown) for electrical connection to the mounting boards of
various equipment.
[0149] The magnetic sensors 102, 103 are one type of so-called
wafer-level CSPs, and comprise magnetic sensor chips 107 and 108
formed in sheets of rectangular shape in plane view, and a
plurality of electrode portions 110, 111 provided protruding from
the surfaces 107a, 108a of the magnetic sensor chips 107, 108.
[0150] Four magnetic sensor elements 113 are provided within the
magnetic sensor chips 107 and 108, in thin film form. Each of these
magnetic sensor elements 113 senses the magnetic component of an
external magnetic field in one direction, and measures the
magnitude of the magnetic component in this direction. One each of
these magnetic sensor elements 113 is placed at a position adjacent
to each of the edges of the surfaces 107a, 108a of the magnetic
sensor chips 107 and 108, at a distance from each other, so that
the magnetic sensor chips 107 and 108 sense the magnetic components
in two orthogonal directions ((A, B) and (C, D)) along the surfaces
107a, 108a.
[0151] The electrode portions 110, 111 electrically connect the
magnetic sensor chips 107, 108 to the circuit board 105, and are
arranged in one row on the surfaces 107a, 108a of the magnetic
sensor chips 107 and 108, for example in the direction parallel
with one edge 107b, 108b adjacent to one edge of the chip. Each of
the electrode portions 110, 111 comprises a solder ball of solder
formed into a substantially spherical shape, and all are formed in
the same size. These electrode portions 110, 111 can be configured
so as to be capable of adhesion to land portions 115 formed on the
surface 105a of the circuit board 105, and by this means the
magnetic sensors 102, 103 are electrically connected to the circuit
board 105.
[0152] These magnetic sensors 102 and 103 are placed such that the
magnetic sensor chips 107, 108 are inclined with respect to the
surface 105a of the circuit board 105. That is, the pluralities of
electrode portions 110, 111 protrude from the surfaces 107a, 108a
of the magnetic sensor chips 107, 108, arranged in a row along a
certain edge 107b, 108b, in the direction parallel to the edges
107b, 108b. Consequently with the pluralities of electrode portions
110, 111 in contact with land portions 115 of the circuit board
105, the other edges 107c, 108c on the side opposite the certain
edges 107b, 108b of the magnetic sensor chips 107, 108 on which are
placed the electrode portions 110, 111 are in contact with the
surface 105a of the circuit board 105. Hence the magnetic sensor
chips 107, 108 are inclined such that the surfaces thereof 107a,
108a gradually move away from the surface 105a of the circuit board
105 in moving from the other edge 107c, 108c toward the certain
edge 107b, 108b. The directions of inclination of the magnetic
sensors 102, 103 are directions orthogonal to the direction of
arrangement of the two magnetic sensors 102, 103.
[0153] Further, the two magnetic sensors 102, 103 are placed such
that the certain edge 107b of one of the magnetic sensors 102 and
the other edge 108c of the other magnetic sensor 103 are adjacent,
and moreover the other edge 107c of one of the magnetic sensors 102
and the certain edge 108b of the other magnetic sensor 103 are
adjacent. Consequently the two magnetic sensor chips 107, 108 are
inclined in opposite directions. The two magnetic sensor chips 107,
108 are inclined by an angle of inclination .theta. with respect to
the surface 105a of the circuit board 105 which is of the same
magnitude.
[0154] The directions of sensitivity A through D of the two
magnetic sensors 102 and 103 placed as described above are as
follows. In the figures, the X axis and Y axis denote mutually
orthogonal directions along the surface 105a of the circuit board
105, and the Z axis denotes the thickness direction of the circuit
board 105.
[0155] The direction of sensitivity A of one of the magnetic
sensors 102, orthogonal to the direction of placement of the
electrode portions 110, is the direction inclined by the angle
.theta. from the negative Y-axis direction toward the positive
Z-axis direction. The direction of sensitivity B of the magnetic
sensor 102, orthogonal to the direction of sensitivity A, is the
negative X-axis direction. The direction of sensitivity C of the
other magnetic sensor 103, orthogonal to the direction of placement
of the electrode portions 111, is the direction inclined by the
angle .theta. from the positive Y-axis direction toward the
positive Z-axis direction. The direction of sensitivity D of the
other magnetic sensor 103, orthogonal to the direction of
sensitivity C, is the positive X-axis direction.
[0156] Hence the direction of sensitivity A of one of the magnetic
sensors 102 is a direction which intersects the plane comprising
the two directions of sensitivity C, D of the other magnetic sensor
103. Similarly, the direction of sensitivity C of the other
magnetic sensor 103 is a direction which intersects the plane
comprising the two directions of sensitivity A, B of the one
magnetic sensor 102.
[0157] A magnetic sensor unit 1 configured as described above
detects magnetic components in each of the X-axis, Y-axis, and
Z-axis directions, and outputs output values (below, also called
sensitivity) S.sub.x, S.sub.y, S.sub.z which are substantially
proportional to the respective magnetic components. The
sensitivities S.sub.x, S.sub.y, S.sub.z of the magnetic sensor unit
101 may be expressed as follows, using the sensitivities S2.sub.x,
S2.sub.y, S3.sub.x, S3.sub.y of the magnetic sensors 102, 103.
S.sub.X=S2.sub.x+S3.sub.x S.sub.y=(S2.sub.y+S3.sub.y)cos .theta.
S.sub.z=(S2.sub.y+S3.sub.y)sin .theta.
[0158] The sensitivities S2.sub.x, S2.sub.y denote the
sensitivities in the directions of sensitivity B, A respectively of
the magnetic sensor 102, and the sensitivities S3.sub.x, S3.sub.y
denote the sensitivities in the directions of sensitivity D, C
respectively of the magnetic sensor 103.
[0159] Referring to the above equations, if the range of the angle
of inclination .theta. is 0.degree.<.theta.<90.degree., then
the direction of a magnetic field can be measured as a vector in
three-dimensional space. If the angle of inclination .theta. of the
magnetic sensor chips 107, 108 is smaller than 45.degree., then the
sensitivity in the Z-axis direction S.sub.z is lower than the
sensitivity in the Y-axis direction S.sub.y. Conversely, if the
angle of inclination .theta. is greater than 45.degree., the
sensitivity in the Y-axis direction S.sub.y is lower than the
sensitivity in the Z-axis direction S.sub.z. Hence by setting the
angle of inclination .theta. to 45.degree., the sensitivity along
the axis with the lowest sensitivity can be increased.
[0160] This angle of inclination .theta. can be set appropriately
by changing the diameters of the electrode portions 110 and 111,
that is, by changing the protrusion lengths of the electrode
portions 110, 111 protruding from the surfaces 107a, 108a of the
magnetic sensor chips 107, 108.
[0161] By means of the above magnetic sensors 102 and 103, because
pluralities of electrode portions 110, 111 are arranged in a row to
protrude from the surfaces 107a, 108a of the magnetic sensor chips
107, 108, directions of magnetic sensitivity of the magnetic sensor
chips 107, 108 are inclined with respect to the surface 105a of the
circuit board 105, so that a magnetic component in a direction
intersecting the surface 105a of the circuit board 105 can be
detected by the magnetic sensor chips 107, 108.
[0162] Further, the electrode portions 110, 111 need only be fixed
to land portions 115 of the circuit board 105, so that the magnetic
sensors 102, 103 can be mounted on the circuit board 105 in an
inclined state, without heating the entirety of the magnetic sensor
chips 107, 108. Hence fluctuation and degradation of the
characteristics of the magnetic sensor chips 107, 108 can be
prevented, and the direction of a magnetic field can be measured
correctly.
[0163] Further, by means of the above magnetic sensor unit 101,
because magnetic sensors 102, 103 are used in which fluctuation and
degradation of the characteristics of the magnetic sensor chips
107, 108 are prevented, the three-dimensional direction of a
magnetic field can be measured correctly.
[0164] In this second aspect, the angle of inclination .theta. of
the magnetic sensor chips 107, 108 is set by changing the
protrusion length of the electrode portions 110, 111 placed on one
edge 107b, 108b of the magnetic sensor chips 107, 108; but other
configurations are possible, and the angle of inclination .theta.
may be set through the placement of the electrode portions 110, 111
with respect to the magnetic sensor chips 107, 108. That is, as for
example in FIG. 15 and FIG. 16, the positions of the pluralities of
electrode portions 110, 111 placed in a row may be shifted from the
one edge 107b, 108b toward the other edge 107c, 108c of the
magnetic sensor chips 107, 108, to increase the angle of
inclination .theta.. In the case of this configuration, the
electrode portions 110, 111 and the magnetic sensor elements 113 do
not overlap in the thickness direction of the magnetic sensor chips
107, 108, so that when mounting the magnetic sensors 102, 103 on
the circuit board 105, stress from the electrode portions 110, 111
can be suppressed, and fluctuations in the characteristics of the
magnetic sensor elements 113 arising from this stress can be
suppressed.
[0165] Here, if a is the length from the one edge 107b, 108b of the
magnetic sensor chips 107, 108 to the positions of the electrode
portions 110, 111 on the magnetic sensor chips 107, 108, and b is
the length from the one edge 107b, 108b of the magnetic sensor
chips 107, 108 to the other edge 107c, 108c, then as shown in FIG.
17, the greater is the ratio of a to b, the larger is the angle of
inclination .theta. of the magnetic sensor chips 107, 108. Further,
the rate of increase of the angle of inclination .theta. is greater
as a becomes larger.
[0166] The values of the angle of inclination .theta. in this graph
are for a case in which the length b of one edge of the magnetic
sensor chips 107, 108 is 2.0 mm and the diameter of the electrode
portions 110, 111 is 300 .mu.m. Also, in order that short-circuits
across electrode portions 110, 111 do not occur, the interval
between adjacent electrode portions 110, 111 is 200 .mu.m.
[0167] As explained above, when setting the angle of inclination
.theta., there is no need to change the size of the electrode
portions 110, 111, so that the angle of inclination .theta. can
easily be set.
[0168] Further, the two magnetic sensors 102, 103 are placed such
that the certain edge 107b of one of the magnetic sensors 102 and
the other edge 108c of the other magnetic sensor 103 are adjacent,
and moreover the other edge 107c of one of the magnetic sensors 102
and the certain edge 108b of the other magnetic sensor 103 are
adjacent; but other configurations are possible. For example, as
shown in FIG. 18, the two magnetic sensors 102, 103 may be placed
such that the certain edges 107b, 108b of the magnetic sensors 107,
108 are opposed. Or, for example as shown in FIG. 19, the two
magnetic sensors 102, 103 may be placed such that the other edges
107c, 108c of the magnetic sensor chips 107, 108 are opposed.
[0169] Further, the other edges 107c, 108c of the magnetic sensor
chips 107, 108 are brought into contact with the surface 105a of
the circuit board 105; but other configurations are possible, and a
configuration may be employed in which a cutout portion may be
formed in the surface 105a of the circuit board 105, and the other
edges 107c, 108c of the magnetic sensor chips 107, 108 are inserted
into this cutout portion. In the case of this configuration, the
two magnetic sensors 102, 103 can easily be positioned with respect
to the circuit board 105.
[0170] Also, in addition to simply bringing the other edges 107c,
108c of the magnetic sensor chips 107, 108 into contact with the
surface 105a of the circuit board 105, the other edges 107c, 108c
of the magnetic sensor chips 107, 108 may be fixed to the surface
105a of the circuit board 105 using solder.
[0171] In the above-described aspect, an example was explained in
which the directions of sensitivity A through D and the direction
of inclination of the magnetic sensors 102, 103, and the directions
of placement of the terminals 110, 111, are either parallel or
orthogonal; but other configurations are possible, and the
directions of sensitivity A through D and directions of inclination
of the magnetic sensors 102, 103, and the directions of placement
of the terminals 110, 111, may be at any arbitrary angle between
0.degree. and 90.degree..
[0172] Further, the magnetic sensors 102, 103 are both placed on
the surface 105a of the circuit board 105; but other configurations
are possible, and it is sufficient that directions of sensitivity
of each of the magnetic sensor chips 107, 108 intersect. Hence as
for example shown in FIG. 20, a configuration may be employed in
which the other edge 108c of the other magnetic sensor chip 108 is
placed on the rear surface 107d of one of the magnetic sensor chips
107, such that a portion of the two magnetic sensor chips 107, 108
overlaps in the thickness direction of the circuit board 105. Or,
as for example shown in FIG. 21, the other edge 108c and the
electrode portions 111 of the other magnetic sensor 103 are placed
on the rear surface 107d of the one magnetic sensor chip 107, such
that the entirety of the two magnetic sensor chips 107, 108
overlaps in the thickness direction of the circuit board 105. Here,
electrical connection of the electrode portions 111 of the other
magnetic sensor 103 with the circuit board 105 may for example be
achieved via a bendable flexible wiring plate 114, or wiring placed
in the interior of the one magnetic sensor chip 107 may be used to
effect the electrical connection.
[0173] When, as described above, two magnetic sensors 102, 103 are
placed so as to overlap on the surface 105a of a circuit board 105,
the mounting area of the two magnetic sensors 102, 103 on the
circuit board 105 can be made small, so that the size of the
magnetic sensor unit can be reduced.
[0174] Further, the electrode portions 110, 111 are formed from
solder balls, but other configurations may be employed, and it is
sufficient that the electrode portions 110, 111 protrude from the
surfaces 107a, 108a of the magnetic sensor chips 107, 108. That is,
as for example shown in FIG. 22A, a configuration may be employed
in which a solder ball 117 is placed on the surface 116a of the
magnetic sensor chip 116, a ball is formed from gold wire on this
solder ball 117, and the tip portion is cut to form a so-called
stud bump 118, stacking to obtain the electrode portion 119. In
this configuration, as shown in FIG. 22B, the stud bump 118 adheres
to the pad portion 115 of the circuit board 105. In the case of
this configuration, by stacking stud bumps 118, the amount of
protrusion of the electrode portion 119 from the surface 116a of
the magnetic sensor chip 116 can be changed, so that the angle of
inclination .theta. can easily be set.
[0175] Next, FIG. 23 and FIG. 24 show a third aspect of the
invention. The basic configuration of this aspect is the same as
that of the magnetic sensor unit 101 shown in FIG. 13 and FIG. 14,
but the configuration of each of the magnetic sensors is different.
Here, the magnetic sensors in FIG. 23 and FIG. 24 are explained;
portions which are the same constituents as in FIG. 13 and FIG. 14
are assigned the same symbols, and explanations are omitted.
[0176] As shown in FIG. 23 and FIG. 24, the magnetic sensor unit
120 comprises a circuit board 105 and two magnetic sensors 121, 122
mounted on the surface 105a of the circuit board 105. Each of the
magnetic sensors 121 and 122 comprises a magnetic sensor chip 123,
124, and a plurality of electrode portions 126 to 129 provided on
the surfaces 123a, 124a thereof. Similarly to those in the second
aspect, each of the magnetic sensor chips 123, 124 measures a
magnetic component of an external magnetic field, and is sensitive
to magnetic components in two orthogonal directions along the
surfaces 123a, 124a thereof. The electrode portions 126 to 129
comprise solder balls in which solder is formed into a
substantially spherical shape, and are placed separated into two
parallel rows.
[0177] The electrode portions 126, 128 arranged in one of the rows
are formed so as to be larger than the electrode portions 127, 129
arranged in the other row. Consequently, with these electrode
portions 126 to 129 adhering to land portions 115 of the circuit
board 105, each of the magnetic sensor chips 123, 124 is inclined
with respect to the surface 105a of the circuit board 105.
[0178] These two magnetic sensors 121, 122 are placed such that the
larger electrode portions 126 of one magnetic sensor 121 and the
smaller electrode portions 129 of the other magnetic sensor 122 are
adjacent, and moreover the smaller electrode portions 127 of the
one magnetic sensor 121 and the larger electrode portions 128 of
the other magnetic sensor 122 are adjacent. Consequently the two
magnetic sensor chips 107, 108 are inclined in opposite directions.
These two magnetic sensor chips 107, 108 are inclined at the same
angle of inclination .theta. with respect to the surface 105a of
the circuit board 105.
[0179] By this means, the plane comprising the two directions of
sensitivity of one of the magnetic sensors 121 intersects with at
least one of the directions of sensitivity of the other magnetic
sensor 122.
[0180] By means of the magnetic sensors 121, 122 and the magnetic
sensor unit 120, advantageous results similar to those of the
second aspect are obtained, and in addition, when the numbers of
electrode portions 126 to 129 provided on the surfaces 123a, 124a
of the magnetic sensor chips 123, 124 are determined in advance, by
arranging the electrode portions 126 to 129 separated into two
rows, the number of electrode portions 126 to 129 placed in each
row can be reduced, so that the magnetic sensor chips 123, 124 can
easily be formed. Hence the magnetic sensors 121, 122 and the
magnetic sensor unit 120 can be made smaller.
[0181] In this third aspect, all the electrode portions 126 to 129
of the two magnetic sensors 121, 122 are brought into contact with
land portions 115 of the circuit board 105; but other
configurations may be employed, and it is sufficient that
directions of sensitivity of the magnetic sensor chips 123, 124
intersect.
[0182] Hence the electrode portions 129 of one row of the other
magnetic sensor 122 may be placed on the rear surface of the one
magnetic sensor chip 123, such that a portion of the two magnetic
sensor chips 123, 124 overlap in the thickness direction of the
circuit board 105. Further, as for example shown in FIG. 25, the
electrode portions 128, 129 of the other magnetic sensor 122 may be
placed on the rear surface 123d of the one magnetic sensor chip
123, so that the entirety of the two magnetic sensors 121, 122
overlap in the thickness direction of the circuit board 105.
[0183] As explained above, when two magnetic sensors 121, 122 are
placed, overlapping, on the rear surface 105 of a circuit board
105, the mounting area of the two magnetic sensors 121, 122 on the
circuit board 105 can be made small, so that the size of the
magnetic sensor unit can be reduced.
[0184] In the above configuration, electrical connection of the
electrode portions 128, 129 of the other magnetic sensor 122 with
the circuit board 105 may for example be achieved via a bendable
flexible wiring plate 114, or wiring placed in the interior of the
one magnetic sensor chip 123 may be used to effect the electrical
connection.
[0185] Further, the electrode portions 126 to 129 are formed from
solder balls, but other configurations may be employed, and it is
sufficient that [the electrode portions 126 to 129] protrude from
the surfaces 123a, 124a of the magnetic sensor chips 123, 124. That
is, as for example shown in FIG. 26A, a configuration may be
employed in which solder balls 132, 133 the protrusion amounts from
the surface 131a of the magnetic sensor chip 131 of which are equal
are placed into two separate rows, and stud bumps 134 are stacked
onto only the solder balls 132 in one row to form the electrode
portions 135. In such a configuration, as shown in FIG. 26B, the
solder balls 133 and stud bumps 134 of the other row adhere to the
pad portions 115 of the circuit board 105. In the case of this
configuration, by stacking stud bumps 134 onto only the solder
balls 132 of one row, the protrusion amounts of the electrode
portions 135 can be changed, and so the angle of inclination
.theta. can be easily set.
[0186] Further, the electrode portions 126 to 129 are separated and
placed in two parallel rows; but other configurations are possible,
and it is sufficient that placement be such that the surfaces 123a,
124a of the magnetic sensor chips 123, 124 are inclined with
respect to the surface 105a of the circuit board 105. That is, the
electrode portions need only be placed on the surfaces of the
magnetic sensor chips arranged into a plurality of parallel rows
along the surface of the magnetic sensor chip, with protrusion
lengths decreasing gradually in the direction of placement of the
plurality of rows.
[0187] In the magnetic sensor units 101, 120 described in the
second and third aspects, the magnetic sensors 102, 103, 121, 122
are sensitive to magnetic components of a magnetic field in two
directions; but this is not necessary, and it is sufficient to use
at least two magnetic sensors 102, 103, 121, 122 to measure the
direction of a magnetic field as a vector in three-dimensional
space. That is, it is sufficient that one magnetic sensor be
sensitive to magnetic components in two directions, and that the
other magnetic sensor be sensitive in one direction intersecting
with the plane comprising the two directions of sensitivity of the
one magnetic sensor.
[0188] Further, the two magnetic sensor chips 107, 108, 123, 124
are inclined relative to each other through the placement and sizes
of the electrode portions 110, 111, and 126 to 129 of the magnetic
sensors 102, 103, 121, 122; but other configurations are possible,
and taking the rear surface 105b of the circuit board 105 as
reference, it is sufficient that at least one of the magnetic
sensor chips be inclined with respect to the rear surface of the
circuit board so as to induce a partial change in the sum of the
height dimensions of the circuit board and electrode portions in
the thickness direction of the circuit board.
[0189] That is, for example as shown in FIG. 27, the surface of the
circuit board 151 may be formed into a staircase shape, and
electrode portions 143 of two magnetic sensors 141, 142 placed on
the top faces 151a of each of the steps, to configure the magnetic
sensor unit 140. In the case of this configuration, the height from
the rear surface 151b of the circuit board 151 to the top faces
151b of each of the steps differs, so that even if all the
electrode portions of the magnetic sensors 141, 142 are formed in
the same size, the magnetic sensor chips 144, 145 of the magnetic
sensors 141, 142 can easily be inclined with respect to the rear
surface 151b of the circuit board 151.
[0190] A BGA (Ball Grid Array) in which solder balls 152 are formed
as terminals on the rear surface 151b is used for the circuit board
151 of the magnetic sensor unit 140; but other configurations are
possible. For example, in place of the solder balls 152, a PGA (Pin
Grid Array) provided with grid pins may be used.
[0191] Further, as for example shown in FIG. 28, a groove portion
155 may be formed in the surface 153a of the circuit board 153, and
electrode portions 148 of a magnetic sensor 147 placed on the
surface 153a of the circuit board 153 and on the floor face (upper
face) 155a of the groove portion 155. In the case of this
configuration also, the heights from the rear surface 153b of the
circuit board 153 to the surface 153a and to the floor face 155a of
the groove portion 155 are different, so that the magnetic sensor
chip 149 of the magnetic sensor 143 can easily be inclined with
respect to the rear surface 153b of the circuit board 153.
[0192] The electrode portions 110, 111, and 126 to 129 were formed
using solder balls, but it is sufficient that the electrode
portions be formed comprising, at least, an object which protrudes
from the surface of the magnetic sensor chip; for example,
electrode portions may comprise protruding portions formed by
plating or by screen printing to apply a copper paste.
[0193] In the above, aspects of the invention have been described
in detail, referring to the figures. However, specific
configurations are not limited to these aspects, but comprise
design modifications and similar within a range which does not
deviate from the gist of the invention.
* * * * *