U.S. patent application number 10/781848 was filed with the patent office on 2004-11-11 for semiconductor die package having mesh power and ground planes.
This patent application is currently assigned to Silicon Bandwidth, Inc.. Invention is credited to Cangellaris, Andreas C., Crane, Stanford W. JR., Jeon, Myoung-soo, Ogata, Charley Takeshi, Schutt-Aine, Jose, Wang, Ton-Yong.
Application Number | 20040222514 10/781848 |
Document ID | / |
Family ID | 26954403 |
Filed Date | 2004-11-11 |
United States Patent
Application |
20040222514 |
Kind Code |
A1 |
Crane, Stanford W. JR. ; et
al. |
November 11, 2004 |
Semiconductor die package having mesh power and ground planes
Abstract
A cluster grid array semiconductor die package and mating socket
provide electrical connection between one or more semiconductor
dies housed within the die package and substrate, such as a printed
circuit board, on which the mating socket is mounted. The die
package and the mating socket may be easily connected and
disconnected. The die package may include power and ground planes
built into and distributed within the housing of the die
package.
Inventors: |
Crane, Stanford W. JR.;
(Santa Clara, CA) ; Jeon, Myoung-soo; (Fremont,
CA) ; Ogata, Charley Takeshi; (San Jose, CA) ;
Wang, Ton-Yong; (Fremont, CA) ; Cangellaris, Andreas
C.; (Champaign, IL) ; Schutt-Aine, Jose;
(Savoy, IL) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
Silicon Bandwidth, Inc.
|
Family ID: |
26954403 |
Appl. No.: |
10/781848 |
Filed: |
February 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10781848 |
Feb 20, 2004 |
|
|
|
09867438 |
May 31, 2001 |
|
|
|
60270635 |
Feb 23, 2001 |
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Current U.S.
Class: |
257/697 |
Current CPC
Class: |
H05K 7/1061 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101; H05K 7/1076
20130101; H01L 2924/0002 20130101; H01R 12/52 20130101 |
Class at
Publication: |
257/697 |
International
Class: |
H01L 023/48 |
Claims
1-26. (cancelled).
27. A method for manufacturing a semiconductor die package,
comprising: molding a package base including a plurality of side
walls and a floor having a plurality of holes formed therethrough,
wherein interior surfaces of the side walls and floor form a cavity
sized to hold a semiconductor die and wherein said molding includes
molding an electrically conductive frame into the floor, said frame
having a plurality of holes formed therein and the holes through
the floor register with the holes of said frame; and inserting
electrically-conductive pins into the holes in the floor such that
the pins pass into the holes of the frame and extend from an
exterior surface of the floor.
28. The method of claim 27, further comprising: electrically
connecting a semiconductor die to the pins and to the frame; and
attaching a lid to the side walls of the base, the lid and the base
sealing the semiconductor die therein.
29. The method of claim 28, wherein said step of electrically
connecting comprises: coupling solder balls to the pins and to the
frame and coupling the semiconductor die to the solder balls.
30. The method of claim 28, wherein the step of electrically
connecting comprises: coupling solder balls to the pins and to the
frame; placing a substrate over the solder balls; placing the
semiconductor die on the substrate; and electrically connecting the
semiconductor die to the substrate.
Description
[0001] This application claims the benefit of priority based on
provisional Application No. 60/270,635, filed on Feb. 23, 2001, and
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a semiconductor die package
having mesh power and ground planes and a method for manufacturing
such a die package.
[0004] 2. Description of the Related Art
[0005] A semiconductor die or chip is an electrical component on
which a microcircuit is built. The microcircuits can be
interconnected together on the printed circuit board to form larger
electronic circuits for use in radios, televisions, compact disc
players, and computers, to name just a few. Because the
semiconductor die is fragile, it is encased in a semiconductor die
package to protect it from the environment. If one were to look
inside an electronic device, such as a computer, compact disc
player, or cell phone, one would see one or more printed circuit
boards on which semiconductor die packages are mounted and
electrically interconnected.
[0006] The semiconductor die package includes a housing that holds
the semiconductor die and conductive leads or pins that extend from
the bottom or sides of the housing. The conductive leads are
electrically connected to the semiconductor die within the housing.
The outside ends of the leads are typically connected to conductive
paths on the printed circuit board or plugged into a socket on the
printed circuit board. This secures the semiconductor die package
to the printed circuit board and permits electrical signals to pass
between the semiconductor die and other components on the printed
circuit board.
[0007] The integrated circuits built on semiconductor dies are
becoming increasingly powerful. As processing power has increased,
the number of inputs and outputs between semiconductor dies and
other circuit components has increased as well and is expected to
increase further. Die packages must provide a larger number of
leads or pins without significantly increasing the size of the
package. In addition, semiconductor devices are being designed with
lower operating power voltages in order to reduce size and power
consumption. Notwithstanding lower power consumption, thermal
performance remains an important factor in package design. As the
operating power is lowered and device speeds increase, signal
integrity has become increasingly important concern. For example,
in device operation, fluctuations in power and ground voltages
should be limited. Large fluctuations in power and ground are not
only inefficient, but may cause erroneous operation and may even
damage the integrated circuitry on the die. Moreover, parasitic
inductances should be reduced to facilitate high-speed operation.
Accordingly, there is a need for packages that are inexpensive,
that can accommodate a large number of inputs and outputs, and that
can support high speed, low power operation.
SUMMARY OF THE INVENTION
[0008] The present invention has been made in view of the above
circumstances and has as an object to provide an economical,
compact die package having large number of inputs and outputs.
[0009] A further object is to provide an economical, compact die
package and mating socket having large number of inputs and outputs
that may mounted be to a substrate, such as a printed circuit
board.
[0010] A further object is to provide a die package having stable
power and ground planes.
[0011] A further object is to provide a die package having cost
effective power and ground planes.
[0012] A further object is to provide a die package having easily
configurable power and ground planes.
[0013] A further object to provide an economical die package having
stable power and ground planes and a mating socket that may mounted
be to a substrate, such as a printed circuit board.
[0014] A further object of the invention is to provide a sturdy and
reliable die package having a large number of inputs and outputs
and stable power and ground planes.
[0015] A further object of the invention is to provide an improved
power and ground plane arrangement that may be used with a die
package, with a mating socket, or with a substrate.
[0016] Additional objects and advantages of the invention will be
set forth in part in the description which follows, and in part
will be obvious from the description, or may be learned by practice
of the invention. The objects and advantages of the invention will
be realized and attained by means of the elements and combinations
particularly pointed out in the appended claims.
[0017] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate embodiment(s)
of the invention and together with the description, serve to
explain the principles of the invention.
[0019] FIGS. 1 and 2 provide perspective views of an illustrative
embodiment of a cluster grid array die package and mating socket in
accordance with the present invention.
[0020] FIG. 3 provides a perspective view of an illustrative
embodiment of a cluster grid array die package in accordance with
the present invention.
[0021] FIG. 4 provides a view of an illustrative embodiment of a
housing base of the cluster grid array die package without
substrate in accordance with the present invention.
[0022] FIG. 5 provides a view of an illustrative embodiment of
power and ground planes in the housing base in accordance with the
present invention.
[0023] FIGS. 6 and 7 provide views of an illustrative embodiment of
the power and ground planes in the housing base in accordance with
the present invention.
[0024] FIG. 8 provides a perspective view of a further illustrative
embodiment of power and ground planes in the housing base in
accordance with the present invention.
[0025] FIGS. 9 and 10 provide side and bottom views, respectively,
of the further illustrative embodiment of the power and ground
planes in the housing base in accordance with the present
invention.
[0026] FIG. 11 provides a view of an illustrative embodiment of a
mating socket in accordance with the present invention.
[0027] FIG. 12 provides a view of an illustrative bottom view of
the mating socket and printed circuit board pad or substrate layout
to which the mating socket may be attached in accordance with the
present invention.
[0028] FIG. 13 provides a further illustrative bottom view of the
mating socket in accordance with the present invention.
[0029] FIG. 14 provides a further illustrative bottom view of the
mating socket in accordance with the present invention.
[0030] FIG. 15 shows an illustrative embodiment of a single
buttress and cluster of package pins in accordance with the present
invention.
[0031] FIG. 16 shows a cross section of an illustrative embodiment
of the die package of FIG. 7.
[0032] FIGS. 17 and 18 show an illustrative electrical path between
a die or substrate and a circuit board through a cluster grid array
die package and mating socket.
[0033] FIGS. 19 and 20 show the mating of pin clusters of a cluster
grid array die package and a mating socket according to an
illustrative embodiment of the present invention.
[0034] FIG. 21 illustrates an exemplary embodiment of a mating
socket in accordance with the present invention.
[0035] FIG. 22 illustrates a cutaway sectional view of the
embodiment of FIG. 22.
[0036] FIG. 23 illustrates an exemplary embodiment of a die carrier
in accordance with the present invention.
[0037] FIG. 24 provides a cutaway sectional view of the embodiment
of FIG. 23.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] Reference will now be made in detail to the present
exemplary embodiment(s) of the invention illustrated in the
accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts.
[0039] FIGS. 1 and 2 illustrate an exemplary embodiment of a
cluster grid array semiconductor die package 100 and a mating
socket 200 in accordance with the present invention. The die
package 100 includes a housing 110 that houses at least one
semiconductor die. As shown in FIG. 2, a plurality of posts 120
extend from a bottom surface of the housing 110. Package pins 130
extend along the posts 120 and provide electrical paths from an
interior to an exterior of housing 110. The mating socket 200
includes housing 210 having a plurality of sockets 220 in a top
surface. A plurality of socket contacts or beams 230 are arranged
within the sockets 200 as shown in FIG. 1. The socket beams 230
include ends 232 that extend from a bottom surface of the housing
210. The ends 232 may be electrically connected to a printed
circuit board (not shown) or other substrate, for example, by
surface mounting, by plated through hole (PTH) technology, by
press-fit, or by other suitable techniques. For example, if surface
mounting were used, the ends 232 may be soldered to
electrically-conductive pads on the surface of the substrate. As
arrays become smaller, routing challenges escalate accordingly,
especially in high speed, high pin-count devices. Electrical
attributes are often the first to suffer. In high-density
applications, particularly those involving pitches of 0.5 to 0.8 or
less, the ends 232 may be surface mounted to pads at various levels
within a multi-layer substrate, such as a printed circuit board, as
described, for example, in U.S. Pat. Nos. 5,543,586 and 5,659,953,
to maintain a pluggable format.
[0040] The die package 100 mates with the mating socket 200 to form
electrical paths between the at least one semiconductor die within
the package housing 110 and the printed circuit board or substrate
on which the mating socket 200 is mounted. Accordingly, electrical
signals, power, and ground may be coupled to and from the at least
one semiconductor die and the substrate.
[0041] In particular, the bottom surface of the package housing 110
is brought together with the upper surface of the mating housing
210 so that the posts 120 are received in the sockets 220.
Consequently, as described in more detail below, the package pins
130 engage the socket contact beams 230 to form selectively
attachable electrical connections. The package 100 is securely
retained to the mating socket 200 by the force exerted between the
socket contact beams 230 and the package pins 130 or by other
suitable retention features. The die package 100 may be selectively
detached from the mating socket 200 by pulling the die package 100
away from the mating socket 200, thereby slideably releasing the
package pins 130 from the socket contact beams 230. Package 100 may
be provided with, for example, 600-3000 package pins with arrayed
pitches ranging from about 0.5 mm to 1.27 mm. A corresponding
number of socket contact beams 230 may be provided at corresponding
pitches. Of course, these are merely examples and more (or fewer)
pins may be provided at greater or smaller pitches.
[0042] For example, embodiments of the package may be designed to
fit the existing and future needs of high pin-count flip chip
devices. Larger arrays, such as 1 mm and 0.8 mm, may utilize a
spreader substrate to fan out signals from the 0.25 mm and 0.5 mm
pitches to a scale more compatible with current cost-effective
printed circuit board (PCB) technology. In many cases, 0.5 mm
devices can be directly attached to the package structures. The
packages may be designed to be near chip-scale in its smaller
arrays. For example, 2500 inputs/outputs can be accommodated in a
space approximately 32 mm.times.32 mm. The packages 100 and mating
sockets 200 are designed to provide the mechanical stability and
rigidity necessary for true socket operation that provides
sufficient stability to handle the rigors of real-world
handling.
[0043] FIG. 3 shows an illustrative embodiment of the package
housing 110. As shown in FIG. 3, the package housing 110 may
include an upper lid 112 and a lower housing base 114. The upper
lid 112 may be formed, for example, of a thermally conductive
material, such as copper. As such, the upper lid 112 permits heat
to be dissipated from the package housing 110. This permits
semiconductor dies within housing 110 to operate more efficiently.
Alternatively or in addition, the die(s) may be encapsulated within
the lower housing base using a suitable encapsulant. The base 114
may be formed of an electrically-insulative material. The material
may be selected to approximate the thermal expansion properties of
the base material of the semiconductor die, such as silicon,
germanium, gallium arsenide, etc. One suitable material for base
114 is liquid crystal polymer, such as Vectra E130I, which may be
purchased from Ticona of Summit, N.J. Liquid crystal polymer
material is highly accurate in molding operations, maintaining
tight tolerances yet offering high flow during the injection step
of the molding process. Vectra, in its various formulations, has
the potential to be doped to deliver the desired physical
properties for an individual application, enhancing reliability and
overall robustness. Of course, housing base 114 may be formed of
another material or combination of materials as well.
[0044] As shown in FIG. 3, for example, the housing base 114
include indentations 114a-114d. As discussed further below, power
contacts 166 and/or ground contacts 176 may be provided in one or
more of indentations 114a-d. Of course, electrical paths for power
and/or ground may be provided in other ways as well.
[0045] FIG. 4 illustrates a top view of an exemplary embodiment of
the housing base 114. As shown in FIG. 4, the housing base 114
includes a floor 116 and walls 117 that define a cavity 118 in
which one or more semiconductor dies may be held. The cavity 118
may also hold a substrate, such as a multi-layer ceramic or polymer
substrate, upon which one or more semiconductor dies may be
mounted. Such a substrate may be, for example, a spreader substrate
that serves as an adapter for converting the pitch of signals of
the die to a pitch compatible with a printed circuit board or other
substrate to which the die carrier is mounted. Solder balls 150 may
extend from an upper surface of floor 116. The solder balls 150 may
be formed on the ends 132 of package pins 130. Of course, while
solder balls 150 are described herein as an example, the solder
balls 150 may be replaced, in whole or in part, with other
electrical connection elements, such as pads or bumps, conductive
paste or other conductive material or combination of materials, or
simply the ends 132 of the package pins 130 themselves. The solder
balls 150 may be provided in an array, for example, as shown in
FIG. 4. The solder balls 150 may be used to form an electrical
contact to the at least one semiconductor die or the substrate upon
which one or more semiconductor dies are mounted. If a substrate is
provided, the substrate may provide an electrical path from the
solder balls 150 to landings on the upper surface of the substrate.
The semiconductor die(s) may couple directly to the landings or via
other electrical material, such as bonding wires, tape automated
bonds, jumpers, or other suitable electrical coupling. The solder
balls may be applied directly to the semiconductor die, either
before or after dicing the wafer, and then mounted to the die
carrier.
[0046] In an exemplary embodiment, a set of solder balls 150 may be
used for power supply and another set of solder balls 150 may be
used for ground. The remaining solder balls may be available for
signal transmission and/or other purposes. In an exemplary
embodiment, an outer ring 150-1 or ring portion of solder balls 150
may be used for power supply. Another ring of solder balls 150-2
just inside of the outer ring may be used for ground. The rest of
the solder balls 150 may be used as signal paths or other purposes.
In the example shown in FIG. 4, 92 solder balls are used for power
supply, 104 solder balls are used for ground, and 624 solder balls
are available for signals or other purposes.
[0047] FIG. 5 illustrates a section view of an embodiment of
housing 110 taken through base 114 to show power planes 160 and
ground planes 170 within the floor 116. FIG. 5 shows ends 132 of
package pins 130 extending through the floor 116 of the housing
base 114. It should be noted that pairs of the package pins 130 may
be used to provide power and ground connections. As noted above,
solder balls 150 may be formed on the ends 132 of the pins 130. The
particular arrangement of power planes 160 and ground planes 170
shown in FIG. 5 is merely exemplary. The power planes 160 and
ground planes 170 may be formed as planar traces, as wirings, as
frames, or another suitable shape.
[0048] The power plane 160 illustrated in FIG. 5 is provided in
four trace segments 161, 162, 163, and 164. Segments 161, 162, 163,
and 164 extends along the periphery of floor 116 between
indentations 114a and 114b, indentations 114b and 114c,
indentations 114c and 114d, and indentations 114d and 114a,
respectively. As shown, the segments 161-164 may be generally
L-shaped. However, the segments of power plane 160 may be provided
in other shapes, for example, C-shaped, or another suitable shape,
or may be placed above or below each other. The segments 161-164
may be supplied with different supply power voltages, for example,
if the die package housed multiple dies that operate with multiple
power supply voltages. The power plane 160 may be provided by any
number of segments, from a single segment to five or more
segments.
[0049] Ground planes 170 may be formed by trace segments arranged
in rows 171 and trace segments arranged in columns 172 to form a
checkerboard pattern. The rows 171 and columns 172 pass between the
ends 132 of package pins 130. The rows 171 and columns 172 may be
spaced so as to pass between groups of one or more pins 130. As
shown in FIG. 5, for example, the rows 171 and columns 172 divide
the pins 130 into groups of four. FIG. 5 further shows each of the
rows 171 and columns 172 coupled together. However, this is not
required. The rows 171 and columns 172 may form multiple ground
segments, for example, to isolate certain signal paths from others.
For example, the checkerboard pattern shown in FIG. 5 may be easily
converted into two segments by cutting each row line 171 between
two adjacent columns lines 172, into four quarter segments by
further cutting each column line 172 between adjacent row lines
171, etc.
[0050] Power contacts 166 and ground contacts 176 may be provided
at indentations 114a-114d. Electrical connection between the power
and ground planes 160, 170 and the mating socket 200 may be
provided at power and ground contacts 166, 176. The embodiment
shown in FIG. 5 includes two power contacts 166 and two ground
contacts 176 per indentation 114a-114d. However, this is merely
illustrative. Any number (1 or 3 or more) power and ground contact
may be provided. The embodiment of FIG. 5 shows four indentations
114a-114d, but it should be appreciated that 1, 2 (on either
adjacent or opposite sides of housing 110), or more indentations
114 (e.g., multiple indentations on one or more sides of housing
110) may be provided. Moreover, the power and ground contacts 166,
176 need not be provided at indentations 114 at all. Power and
ground contacts may be provided, for example, on the outer sides of
housing base 114 or through the bottom surface of the housing base
114 (e.g., using package pins 130 or otherwise).
[0051] FIG. 6 provides a cutaway view of a section of base 114 to
illustrate one exemplary embodiment for forming contacts 166 and
176. FIG. 7 illustrates the entirety of the embodiment shown in
FIG. 6. As best seen in FIG. 6, the power plane segment 162 may
extend along the base 114 at indentation 114b (not shown) to
provide a power contact 166. Similarly, power plane segment 161 may
form a power contact 166. Ground plane 170 may include one or more
extensions, such as extensions shown in FIG. 6, that extend
laterally along the outer side wall 117 at indentation 114b to form
one or more ground contacts 176.
[0052] The power and ground contacts 166, 176 may contact power and
ground mating pins 240 of mating socket 200 to form an electrical
connection. The power and ground mating pins 240 may have a
resiliently flexible contact beam 244 that flexes outwardly when in
contact with the power and ground contacts 166, 176 to maintain a
normal force for good electrical contact.
[0053] FIG. 6 further illustrates holes 116a in floor 116 in which
solder balls 150 sit. The holes 116a may extend entirely through
the housing base 114 to accommodate package pins 130. Holes 116a to
the power plane 160 and ground plane 170 do not necessarily extend
through housing base 114, but may terminate at the power and ground
planes 160, 170. As shown in FIG. 4, such holes 116a enable the
solder balls 150 to contact the power and ground planes 160, 170 to
form an electrical connection.
[0054] FIG. 7 provides an exploded view of an illustrative
embodiment of the die package 100 to show the electrical contacts.
A semiconductor die 300 and a substrate 310 are received in the
cavity 118 of the housing base 114. The semiconductor die 310
mounts to the substrate 310. The substrate 310 may be a multi-layer
ceramic or polymer substrate that provides electrical connection
between the solder balls 150 and the semiconductor die 300. Such a
substrate 310 may be, for example, a spreader substrate that serves
as an adapter for converting the pitch of signals of the die to a
pitch compatible with a printed circuit board or other substrate to
which the die carrier is mounted. The substrate 310 contacts the
solder balls 150 exposed on the floor 116 of the base 114. Some of
the solder balls 150 contact the package pins 130 and others
contact the power and ground planes 160, 170. The lid 112 seals to
the base 114 to retain the die 300. The die package 100 couples to
the mating socket 200 such that package pins 130 engage socket
contact beams 230 and such that power and ground contacts 166, 176
engage power and ground mating pins 240. Ends 232 of the socket
contact beams 230 (not shown) and ends 242 of mating pins 240 (not
shown) may couple to a substrate, such as a printed circuit
board.
[0055] Because package electrical performance is a factor for
GHz-bandwidth signal transmission and sub-nanosecond switching,
interconnect impedance control through the package is important for
suppressing reflections and attendant noise interactions at the
higher end of the signal spectrum. Maintaining good impedance
control in a structure as three-dimensional as a high-density
package is a challenging undertaking, requiring careful
consideration of how power and ground distribution is effected
through the package. In other words, in addition to designing the
power and ground distribution for reducing inductance during
switching, attention must be paid to providing an effective return
path for the current for all signal traces in the package. This
purpose contributed to the introduction of power/ground planes in
high-speed packages.
[0056] FIGS. 8-10 illustrate an example of an alternative power and
ground mesh combination used on the chip side in the package
housing. As in FIGS. 5-7, the power/ground planes may be positioned
directly under the die or die/substrate combination to assist in
power distribution and signal termination. As shown in FIGS. 8-10,
ground plane 170 may be provided at a first level within the floor
116 of package 100 and the power plane 160 may be provided at a
second level within the floor 116. For example, the power
and/ground planes may be insert molded into the floor of package
100 or attached with an adhesive after the floor, or a portion of
the floor, is molded. In the latter case, the power and ground
planes 160, 170 may be combined into a separate unit. As shown in
FIGS. 8-10, the ground plane 170 is provided between the power
plane 160 and the intended location of the die 300. Of course, as
an alternative, the location of the power plane 160 and the ground
plane 170 may be reversed. A coating may be applied to one or both
of the power and ground planes 160, 170 to electrically insulate
them from each other and other components. The coating(s) may be
extremely thin to reduce inductance, e.g., of the package. The
ground plane 170 may have a grid design of interconnecting rows 171
and columns 172. As above, a plurality of solder balls 150 may be
used to couple the ground plane 170 to the semiconductor die 300 or
to the substrate 310, for example.
[0057] The power plane 160 may also have a grid design of
intersecting rows 165 and columns 167. The power plane 160 is
designed to have a greater overall length and/or width than the
ground plane 170 to improve electrical performance and to simplify
electrical connection to solder balls. Of course, other
arrangements are possible. In the embodiment shown in FIGS. 8-10,
the power plane 160 includes a central row 165 and a central column
167 that intersect at a center plane 168. Of course, additional
rows 165 and columns 167 may be provided if desired.
[0058] Power plane 160 is coupled to solder balls 150 by plugs or
extensions 169 that extend through a hole 116a (not shown) in base
114. In the example illustrated in FIGS. 8-10, extensions 169 are
provided spaced apart at the periphery of power plane 160. This
arrangement provides additional space for pins 130 and/or signal
pin extensions 131, which may be used to connect the signal pins to
the solder balls 150, to the die, or to the substrate. Signal pin
plugs or extensions 131 may be formed by two parts: a vertical
extension 131a and a horizontal extension 131b. Vertical extensions
131a provide a vertical path toward the die 300. Horizontal
extensions 131b may be used to fan out the signal paths between the
die 300 and the package pins 130. Extensions 169 are also provided
at the center plane 168 to permit connection to solder balls. FIGS.
8 and 10 illustrate four extensions 169 providing electrical
connection from the center plane 168 to the solder balls 150. Of
course, additional extensions 169 may be provided between the power
plane 160 and the solder balls 150. Alternatively, extensions 169
may provide electrical contact to the die 300 or to the substrate
310 on which the die is mounted.
[0059] It should be pointed out that for the sake of clarity, the
metallization density in the planes 160, 170 shown in FIG. 8-10
does not reflect the actual metallization density. For example, in
the case of a 0.8 mm-pitch package design with 624 signal pins, the
number of "cells" in the ground mesh 170 may be 156 and the number
of corresponding power cells in the power mesh 160 may be 36. In
the mesh structure, the area array contact with the die is
facilitated for both power and ground with the chip. Furthermore,
the arrangement is such that the "effective" value of the power and
ground inductance introduced by the package remains low. Even
though the quantification of an "effective" value of the power
inductance during switching is difficult, an approximate
calculation of such a quantity is possible by considering in a
qualitative manner those factors that have an impact on its value.
For an example having a 0.8 mm pitch, the calculated value of the
self-partial-inductance of the ground mesh is 0.32 nH.
Additionally, the mutual partial-inductance between the power and
ground mesh in the case of a 0.3 mm separation between them is
found to be 0.2 nH. Thus, the effective value of ground inductance
introduced by the ground mesh during switching is 0.12 nH in this
example.
[0060] A similar calculation can be performed to estimate the
worst-case effective inductance introduced by the power mesh 160.
Assuming the example provided above and that the power mesh
metallization is the same as that of the ground mesh, the
worst-case effective inductance introduced by the power mesh is
found to be 0.23 nH. This value is higher than that of the ground
mesh because of the coarser mesh metallization used for the power
mesh. Remarkably, this value can be reduced even further by
increasing the width and thickness of the metallization. In any
case, it is stressed once more that these are worst-case values for
specific examples, and that the power-ground mesh configuration is
designed in such a manner that the "effective value" of power and
ground inductance can be controlled through the assignment of some
of the pins in the clusters as extra power and ground pins.
[0061] The presence of the ground plane in the package housing
immediately beneath the die likewise allows for impedance control
for those signal traces that need to be fanned out away from the
die. The mesh structure can be added in one or more places,
depending upon the electrical needs. For example, in the case of a
0.8 mm-pitch package design, signal trace impedance values in the
range of 50 to 70 Ohm are easily attainable through selection of
signal trace width and separation from the ground mesh. The same
holds true for signal traces routed between the power and ground
mesh planes, as well as below the power mesh plane. The number of
signal layers that may be used is dependent on input/output pin
count and density, as well as crosstalk constraints.
[0062] FIG. 11 illustrates an exemplary embodiment of a mating
socket 200. As shown, mating socket 200 includes a housing 210
having a floor 216 and side walls 217 that define a cavity 218
sized to receive the die package 100. The floor 216 includes a
plurality of sockets 220. Sockets 220 are sized and positioned to
receive the posts 120 of the die package 100. Sockets 220 may be
arranged in an array pattern. Socket contact beams 230 are
positioned within the sockets 220. In the example shown in FIG. 11,
four socket contact beams 230 are provided for each socket 220.
However, any number of socket contact beams 230 may be provided per
socket, such as 2, 3, or 5 or more. The socket contact beams 230
extend through and are held in the housing 210. For example, the
housing 210 may include holes formed therethrough into which socket
contact beams 230 are inserted and held via friction, adhesives,
and/or mechanical expedients, such as spurs, wedge, or
tongue-and-groove arrangements. Power and ground mating pins 240
may be similarly held in the housing 210. The embodiment of FIG. 11
includes a cam mechanism 250 with a cam lever 252. The cam
mechanism 250 may be used, as described in more detail below, to
reduce the insertion force needed to plug the die package 100 into
the mating socket 200.
[0063] FIG. 12 illustrates a bottom surface of mating socket 200
and a portion of a substrate, in this case a printed circuit board
400, to which it may be attached. Ends 232 of socket contact beams
230 and ends 242 of mating pins 240 extend from a bottom surface of
housing 210. The ends 232, 242 may contact pads 410 formed on
circuit board 400 to form an electrical connection. In particular,
the ends 232, 242 may be soldered to the pads 410 to retain the
mating socket 200 to the circuit board 400 and at the same time
form an electrical connection. As shown, the pads 410 are arranged
in the same pattern as the ends 232, 242. Traces (not shown) may
lead to contact pads 410 to couple electrical signals to and from
the contact pads. Alternatively, the pads 410 may be replaced by
plated through holes through which the ends 232, 242 may extend.
Solder may be used to electrically connect and retain ends 232, 242
in such through holes. Of course, the description herein is merely
exemplary and other techniques may be used to couple the mating
socket 200 to a substrate.
[0064] FIGS. 13 and 14 illustrate two alternative arrangements of
the bottom surface of mating socket 200. For simplicity, FIGS. 13
and 14 illustrate only the ends 232 of socket contact beams 230.
FIGS. 13 and 14 each illustrate designs incorporating a ground mesh
260. In particular, FIG. 13 shows the bottom surface of mating
socket 200 with an isolation gate structure providing a ground for
signal beams 230. A reduced number of beams 232 is shown for the
sake of clarity. More particularly, the ground mesh 260 includes
electrically-conductive rows 261 and columns 262 that intersect to
divide the ends 232 of beams 230 into groups or cells. While FIG.
13 illustrates a ground mesh 260 that divides the ends 232 of beams
230 into cells of four, the mesh 260 may be designed to divide the
ends into groups of one, two or three, or five or more. The rows
and columns 261 and 262 include bumps 265 for making electrical
contact with the substrate, e.g., printed circuit board, on which
the mating socket 200 is mounted. Bumps 265 are spaced periodically
on the surface of the ground mesh 260. Of course, bumps 265 may be
omitted or replaced by other contact structure.
[0065] An alternative grounding structure, as shown in FIG. 14,
features isolation rows 261, allowing for somewhat lower
manufacturing costs as well as improved airflow beneath the socket
200. As shown in FIG. 14, the rows 261 are provided between every
other row of ends 232 of beams 230. As above, rows 216 may be
provided between every row of ends 232 or between a larger number
of rows. In FIGS. 13 and 14, the meshes 260 are regularly spaced,
but of course irregular mesh spacing may be used if desired.
[0066] As mentioned earlier, in addition to the use of the power
mesh and the peripheral ground pins, the beams 230 in the cluster
or group may also be used for a more direct power distribution to
different locations on the die 300. The presence of the ground
structure 260 facilitates the reduction of the effective power
inductance that the beams 230 present during switching. As a
measure of this inductance value, let us consider the case in which
four beams 230 in one cluster are used as power pins. In a 0.8
mm-pitch design, where the stacking height is 7.6 mm, and a socket
ground structure as detailed in FIG. 14, the "effective" power
inductance during switching is calculated to be 0.23 nH. This value
can be further reduced through the assignment of more of the beams
as power elements.
[0067] FIG. 15 illustrates an example of a post 120 and package
pins 130 that may be used in connection with the present invention.
Post 120 extends from a lower surface of housing base 114. In one
preferred embodiment, the posts 120 are formed simultaneously with
the housing base 114 using a molding process. The post 120 may
include axially-extending grooves 122 spaces around the
circumference of the post 120. The grooves 122 are adapter to
receive at least a portion of package pins 130. The post 120 may
have a generally circular cross section with cut-outs for grooves
122. However, other cross-sectional shapes are possible as well,
such as squares, rectangles, pentagons, hexagons, etc., with or
without grooves 122. Post 120 further includes an angled tip 124.
The tip 124 aids insertion of the post 120 into a socket 220 of the
mating socket 200. The tip 124 may, for example, help to properly
spread socket contact beams 230 in the event of minor
misalignment.
[0068] Package pins 130 include an end portion 132 (not shown in
FIG. 15), a stabilizer portion 133 extending within the housing,
contact portion 134 extending outside of housing 110. The
stabilizer portion 133 functions to hold the pin 130 stable in the
housing and may thicker than the contact portion 134. The contact
portion 134 is adapted to form an electrical connection with socket
contact beams 230. The contact portion 134 may extend in groove
122. The contact portion 134 may include a rounded tip 136. The
rounded tip 136 helps to flex socket pin 130 outwardly during
mating. In the example of FIG. 10, four package pins 130 are
provided per post 120. However, another ratio of pins 130 per post
120 may be used, such as 2, 3, or 5 or more.
[0069] FIG. 16 illustrates an exemplary cross section of die
package 100 through posts 120. Posts 120 extend from the bottom
surface of housing base 114. Package pins 130 extend through the
housing base 114 and along the posts 120 such that a contact
portion 134 is exposed externally of the package housing 110. The
stabilizer portion 133 of each package pin 130 is held within the
housing base 114, for example, by friction, an adhesive, spurs,
and/or other suitable expedients. The portion 133 may be thicker
than the contact portion 134 to provide added stability. Ends 132
of package pins 130 contact solder balls 150, which contact
substrate 310 through holes 116a in floor 116. Holes 116a also
permit solder balls 150 form contacts between power plane 160 and
substrate 310 and between ground plane 170 and substrate 310. As
shown in FIG. 16, the rows 171 and columns 172 of ground plane 170
extend between the package pins 130. Substrate 310 may have
multiple levels and vias that form electrical connections between
its bottom surface, which contacts the solder balls 150 and its
upper surface adjacent die 300. Substrate 310 may make direct
electrical connections with die 300. Alternatively or in addition,
substrate 310 may have bonding pads which electrically couple to
the die 300 via electrically conductive material, such as wire
bonds, tape automated bonding, jumpers, etc. Thermal lid 112 caps
the housing base 114 to retain and protect die 300.
[0070] As noted above, the base 114 may be formed by molding from a
polymer, such as a liquid crystal polymer. Holes 116a may be formed
during the molding process or by removing material after molding.
The electrically-conductive power and ground planes 160, 170 may be
a frame, such as a lead frame, that is molded into the base 114
when the base 114 is formed or may be applied to a surface of the
base 114 after the base is molded. In such a case, an additional
floor piece 116 having holes 116a may be formed over the power and
ground planes 160, 170. Package pins 130 may be cut from wire stock
and machined to the shape shown in the Figures, for example. The
package pins 130 may be inserted into the holes 116a from the
direction of the cavity 118. If a two-piece base and floor is used,
the pins 130 may be inserted before the floor 116 is applied. In
such a case, it is important that the ends 132 of pins 130 register
with holes 116a. Solder balls 150 are laid over the holes 116a to
contact the ends 132 of pins 130, the power plane 160, and the
ground plane 170. The substrate 310 (if used) and die(s) 300 are
then laid over the solder balls 150. Solder balls 150 may be melted
to form an electrical and mechanical attachment and any other
electrical connection within the cavity 118 may be made (e.g., wire
bonding, etc.). The lid 112 may then be sealed to the base 114 to
complete the package 100.
[0071] As shown in FIG. 16, the lengths of the contact portions 134
of package pins 130 may vary. For example, the length of the
contact portion 134 of pin 130-1 is greater than the length of the
contact portion 134 of pin 130-2. As a result, the contact portions
134 of pins 130-1 and 130-2 engage the corresponding contact beams
234 of the mating socket at different times during mating. In this
way, the insertion force needed to couple the package 100 with the
mating socket 200 may be reduced.
[0072] FIGS. 17 and 18 illustrate an exploded view of an exemplary
electrical connection path between die 300 (or substrate 310) and a
substrate 400, such as a printed circuit board, for a single
cluster of package pins 130 and socket contact beams 230. The
signal paths through the package 100 and the socket 200 are
realized through the four-pin cluster shown in FIGS. 17 and 18. Die
300 couples to solder balls 150, which are in electrical contact
with the ends 132 of package pins 130. As noted above, extensions
or plugs 131 may be provided to couple the ends 132 of pins 130 to
the solder balls 150 or directly to the die 300 or substrate 310.
Contact portions 134 of package pins 130 extend along the post 120
and are spaced apart around the circumference of the post 120. The
post 120 and package pins 130 are received in a socket 220 (not
shown for ease of understanding) and engage socket contact beams
230.
[0073] The socket contact beams 230 include resilient, flexible
contact beams 234 that extend from the housing 210. Contact beams
234 each include an upstanding portion 235, a first angled portion
236, and a second angled portion 237. The first angled portion 236
angles inwardly, toward the space for receiving post 120. The
second angled portion 237 angles outwardly away from the space for
receiving post 120. Accordingly, as the post 120 is received, the
second angled portion 237 helps to spread the contact beam 234
outward away from the post 120. The first angled portion 236 helps
to provide a normal force against the contact portion 134 of the
package pins 130 for a good electrical connection. The socket
contact beams 230 further include a stabilizer portion 233 held
within the housing 210, for example, by friction, adhesive, spurs,
tongue-and-groove, wedge, and/or other expedients. The stabilizer
portion 233 may be thicker than ends 232 and beam 234 to maintain
stability of the pin 230. Ends 232 of socket contact beams 230
extend from a bottom surface of housing 210 and may be surface
mounted, for example, to bonding pads 410 on substrate 400.
Accordingly, as provided in this example, an electrical path is
formed from the die 300, to the solder balls 150, to the package
pins 130, to the socket contact beams, and to the substrate
400.
[0074] The socket housing 210 may be formed by molding, for
example. Similar to the package housing, the socket housing 210 may
be molded from a polymer material and, after molding, the socket
contact beams 230 may be inserted. Alternatively, the socket
housing 210 may be molded around the contact beams 230. In
addition, a ground or shield structure may be added to the socket
housing 210. For example, the ground or shield may be molded into
the socket housing 210.
[0075] FIGS. 19 and 20 illustrate an embodiment in which insertion
of the posts 120 into the socket 220 is aided by cam 250. As noted
above, the contact beams are designed to have an adequate normal
force to maintain positive contact under a variety of conditions
and in numerous product applications. Typically, along with a
substantial normal force of the contact beam comes a correspondent
increase in insertion force. Although not objectionable on a
per-contact beam basis, in a high pin-count configuration the
insertion force may become problematic. To afford both high
reliability and a high pin-count form, zero insertion force (ZIF)
or low insertion force (LIF) options may be supported. In FIGS. 19
and 20, the beams 230 are "cammed" open to provide either zero- or
very low-insertion force.
[0076] As shown in FIGS. 19 and 20, a cam 250 may be positioned
between a cluster of socket contact beams 230. Cam 250 is movable
along the socket contact beams 230 between at least two positions.
In a first position, as shown in FIG. 19, cam 250 engages ridges
238 formed on surfaces of beams 234 of socket contact beams 230.
The ridges 238 may be wedge shaped, for example. As cam 250 is
moved along beams 234 of the socket pin cluster, it engages and
slides along ridges 238, thereby causing the beams to flex
outwardly. Moreover, the sliding interaction of the cam 250 on the
surface of beams 234 provides a significant wiping action to
further assure good electrical contact. In a second position, as
shown in FIG. 20, the cam 250 is located adjacent the housing 210
and does not engage ridges 238. Consequently, cam 250 does not flex
beams 234 outward. Rather, the beam 234 resiliently returns to a
substantially unflexed position.
[0077] The cam mechanism 250 may be used to reduce the insertion
force required to mate the package 100 with the mating socket 200.
For example, the cam 250 may be placed in the first position to
spread the socket contact beams 230 prior to mating with the
package pins 130, as shown in FIG. 19. Once the package pins 130
are placed in position within the cluster of socket contact beams
230, the cam 250 may be moved to the second position, thereby
permitting the socket contact beams 230 to collapse upon the
package pins 130 to form electrical connections. Note that, in
accordance with this embodiment, it is not necessary for the post
120 to contact the cam 250. Cam 250 may be moved using externally
applied pressure, either by man or machine, to a cam lever 252,
shown in FIGS. 11 and 12, for example.
[0078] The semiconductor die packages according to the present
invention take into account electrical, mechanical, and thermal
design considerations to provide the signal integrity useful for
present-day semiconductors. Electrical performance considerations
are important in the package design as next-generation
application-specific integrated circuits (ASICs) and high-end
processors are pushing the input/output frequencies toward the
microwave frequency band. To support such bandwidths without
excessive noise generation and signal degradation, the signal
transmission and power distribution through the package parallel
those used for microwave signal transmission, yet at densities more
than two orders of magnitude greater. In particular, the present
package designs both eliminate parasitic inductance in the power
distribution network and facilitate satisfactory impedance control
through the package.
[0079] With regard to cost, the package designs described herein
exhibit good material efficiency due to highly dense structure and
high material utilization per I/O. Processing costs of assembling
the various components of the package product family are low due to
the straightforward assembly process and the redundant nature of
the cluster structures. The designs permit fully automated
assembly. Moreover, the pluggable aspect of the designs
advantageously enable population of the most expensive components
during the final assembly phase, thereby reducing work in process
and lowering inventory costs.
[0080] The power and ground planes described herein may be provided
in any position of the assembly. The power and ground arrangements
described herein and shown, for example, in FIGS. 5-10, may be used
in other semiconductor die carriers, such as flip chip carriers,
ball grid arrays, etc., may be integrated into the mating socket,
or may be used in printed circuit boards or other substrates (such
as ceramic laminate, organic laminate, or silicon substrate, for
example), to improve electrical performance. The power and ground
planes may be provided, for example, above a substrate, as part of
the substrate, below a substrate, as part of the die carrier, as
part of the mating socket, or any combination of the above. As
noted above, the power and/or ground planes 160, 170 may have a
coating that electrically insulates them. The coating may be
extremely thin to reduce inductance. For example, the power and
ground planes may be applied to a mold and encapsulated so as to
become part of the die carrier 100 or mating socket 200. Further,
the thickness of the ground and power planes may be altered by
stacking additional layers. For example, a stacked
ground/power/ground structure or a stacked power/ground/power
structure may be provided. In general, these power and ground
planes may run perpendicular to the signal pins, however, this is
not required.
[0081] FIGS. 21 and 22 illustrate an exemplary embodiment of a
mating connector 200 in accordance with the present invention. The
mating connector 200 of FIGS. 21 and 22 include many of the
features and properties of the embodiment shown in FIGS. 1 and 2,
for example, and described above. In general, the mating connector
200 includes a housing 210 having a plurality of sockets 220 and a
plurality of electrically-conductive socket beams 230 arranged in
the sockets 230. Housing 210 may include a floor portion 216
through which the sockets 220 are provided and walls 217. Ends 232
of socket beams 230 (not shown in FIG. 21) extend from a bottom
surface of the housing 210 for electrical connection to a
substrate, such as a printed circuit board. As shown in FIGS. 21
and 22, sockets 220 may have a square shape, for example, but other
shapes, e.g., circles, ovals, or polygonal shapes, are possible as
well. Mating connector 200 further includes power and ground mating
pins 240 having resiliently flexible contact beams 244 that flex
outwardly when on contact with the power and ground mating contacts
166 during mating between the die carrier and mating socket 200.
Power and ground mating pins 240 may be provided in individual
passages 212 formed in housing 210. The passages 212 may be
provided, at least partially, in walls 217. As shown in FIG. 21,
the power and ground mating pins 240 may be provided on opposite
sides of housing 200. Of course, the power and ground mating pins
240 may be provided on adjacent sides, on one side only, on three
or four sides, or elsewhere.
[0082] As shown in more detail in FIG. 22, floor 216 may comprise a
first insulative layer 216-1, a ground mesh 270, and a second
insulative layer 216-2. The floor 216 includes holes 216a that at
least partially define sockets 220 and through which the posts 120
and package pins 130 of the die carrier may be inserted. As noted
above, the ground mesh 270 may have a thin coating that insulates
the ground mesh 270, including for example on the surfaces that
define the holes 216a. Of course, the structure between the first
and second insulative layers 216-1 and 216-2 may be a power plane,
a combination of adjacent power and ground planes, or a stack of a
one or more power and ground planes, as discussed above. Housing
210 includes a base 214 on which the floor 216 may be mounted. A
cavity 218 may be defined between the base 214 and the floor 216.
At least the flexible contact beams 234 of the socket beams 230 may
be provided, or extend through, the cavity 218. Accordingly, at
least during mating of the die package 100 and the mating socket
200, the package pins 130 and/or the socket beams 230 will pass
through the ground mesh 270. Stabilizer portions 233 of the socket
beams may be retained in the base 214, for example, by friction,
adhesives, and/or mechanical expedients as noted above. Mating
socket 200 of FIGS. 21 and 22 may additionally include other
features noted above in connection with the other Figures, but for
brevity have not been repeated here.
[0083] The mating socket 200 of FIGS. 21 and 22 may be easily
manufactured. For example, the base 214 may be molded, e.g., from a
liquid crystal polymer material such as VECTRA.TM.. Beams 230 and
240 may be inserted into the molded base 214, or molded into the
base 214. Floor 216 may be formed separately and attached to the
base 214.
[0084] FIGS. 23 and 24 illustrate a further exemplary embodiment of
a die package 100 in accordance with the present invention. As
shown in FIGS. 23 and 24, the die package 100 is generally similar
to that shown in FIGS. 1 and 2, for example, and includes many of
the same structures and features. As above, the die package 100
includes a housing 110, a posts 120 extending from a bottom surface
of housing 110, and package pins 130 extending along the posts 120
as shown in FIG. 24, for example.
[0085] Housing 110 includes a base 114 having a floor 116 and walls
117. The floor 116 and walls 117 define a cavity in which one or
more semiconductor dies may be housed. The die(s) may be enclosed
within the base 114 with a lid (not shown) and/or encapsulant, as
described above. Power contacts 166 and/or ground contacts 176 may
be provided at the periphery of base 114. As shown in FIG. 23, the
power contacts 166 and ground contacts 176 may be provided on
opposite sides of the base 114. As such, the die package 100 may be
mated with the mating socket of FIGS. 21 and 22. Of course, as
noted above, power and/or ground contacts may be provided on one
side, on two adjacent sides, on three or more sides of base 114,
elsewhere.
[0086] Power plane 160 and ground plane 170 are provided within
floor 116. Power plane 160 and ground plane 170 are separated by
insulative material. Power plane 160 includes a grid of
intersecting rows 165 and columns 167. Extensions 169 of power
plane 160 provide access to the surface of floor 116. Ground plane
170 includes a grid design of intersecting rows 171 and columns
172. Ends 132 of package pins 130 are exposed at the surface of
floor 116 so that groups of one or more ends 132 (four in the
example of FIGS. 23 and 24) are provided between the rows 171 and
columns 172. Extensions (not shown) couple the power plane 160 to
the power contacts 166. Likewise, extensions (not shown) couple the
ground plane 170 to the ground contacts 176. Die package 100 of
FIGS. 23 and 24 may additionally include other features noted above
in connection with the other Figures, but for brevity have not been
repeated here.
[0087] It should be borne in mind that the particular embodiments
of the present invention are but possible solutions to the complex
problem of addressing thermal/mechanical and reliability
constraints without sacrificing electrical performance. The
flexibility of the design features described herein allows for a
wide range of solutions that may vary with individual applications.
Additionally, the pluggable alternative now affords systems
architects fresh opportunities to partition their products so as to
provide new levels of sophistication in systems employing high
pin-count devices.
[0088] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *