U.S. patent application number 12/470370 was filed with the patent office on 2010-03-11 for electronic apparatus and printed wiring board.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Kenji Hasegawa, Terunari Kanou, Tsuyoshi Kozai.
Application Number | 20100061067 12/470370 |
Document ID | / |
Family ID | 41799111 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100061067 |
Kind Code |
A1 |
Hasegawa; Kenji ; et
al. |
March 11, 2010 |
ELECTRONIC APPARATUS AND PRINTED WIRING BOARD
Abstract
According to an aspect of the present invention, there is
provided a printed wiring board including: a substrate including an
edge and a fixing hole located adjacent to the edge, the fixing
hole configured to receive a bolt; and a land formed in a vicinity
of the fixing hole and extending in at least a first direction and
a second direction, the first direction being a direction from the
fixing hole toward a center of the substrate, the second direction
being direction along the edge.
Inventors: |
Hasegawa; Kenji;
(Hamura-shi, JP) ; Kozai; Tsuyoshi; (Ome-shi,
JP) ; Kanou; Terunari; (Hamura-shi, JP) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
41799111 |
Appl. No.: |
12/470370 |
Filed: |
May 21, 2009 |
Current U.S.
Class: |
361/752 ;
174/250 |
Current CPC
Class: |
H05K 1/116 20130101;
H05K 3/325 20130101; H05K 2201/09463 20130101; H05K 7/142 20130101;
H05K 5/0247 20130101; H05K 2201/10409 20130101; H05K 1/0215
20130101; H05K 1/02 20130101; H05K 9/0064 20130101 |
Class at
Publication: |
361/752 ;
174/250 |
International
Class: |
H05K 5/00 20060101
H05K005/00; H05K 1/00 20060101 H05K001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2008 |
JP |
2008-232390 |
Claims
1. An electronic apparatus comprising: a casing comprising a
conductive ground layer on an inner surface of the casing; a
printed wiring board in the casing; and a bolt configured to attach
the printed wiring board to the casing and to ground the printed
wiring board to the conductive ground layer, wherein the printed
wiring board comprises: a substrate comprising an edge and a fixing
hole next to the edge, the fixing hole configured to receive the
bolt; and a land in a vicinity of the fixing hole and extending in
at least a first direction and a second direction, the first
direction being a direction from the fixing hole toward a center of
the substrate, the second direction being direction along the
edge.
2. The electronic apparatus of claim 1, wherein: the substrate
comprises a first region extending along the edge and comprising a
band-shape, and the land is outside the first region.
3. The electronic apparatus of claim 2, wherein the land comprises
a sector shape extending from the fixing hole toward the center of
the substrate.
4. The electronic apparatus of claim 3, further comprising a
conductive plating on an inner surface of the fixing hole and
continuous with the land.
5. The electronic apparatus of claim 2, wherein: the substrate
comprises a second region extending at least between the fixing
hole and the center of the substrate, and the land is outside the
second region.
6. The printed wiring board of claim 5, further comprising a
conductive plating on an inner surface of the fixing hole and
continuous with the land.
7. A printed wiring board comprising: a substrate comprising an
edge and a fixing hole next to the edge, the fixing hole configured
to receive a bolt; and a land in a vicinity of the fixing hole and
extending in at least a first direction and a second direction, the
first direction being a direction from the fixing hole toward a
center of the substrate, the second direction being direction along
the edge.
8. The printed wiring board of claim 7, wherein: the substrate
comprises a first region extending along the edge and comprising a
band-shape, and the land is outside the first region.
9. The printed wiring board of claim 8, wherein the land comprises
a sector shape extending from the fixing hole toward the center of
the substrate.
10. The printed wiring board of claim 9, further comprising a
conductive plating on an inner surface of the fixing hole and
continuous with the land.
11. The printed wiring board of claim 8, wherein: the substrate
comprises a second region extending at least between the fixing
hole and the center of the substrate, and the land is outside the
second region.
12. The printed wiring board of claim 11, further comprising a
conductive plating on an inner surface of the fixing hole and
continuous with the land.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2008-232390, filed on
Sep. 10, 2008, the entire contents of which are incorporated herein
by reference.
BACKGROUND
[0002] 1. Field
[0003] An aspect of the present invention relates to a printed
wiring board having lands and an electronic apparatus equipped with
it.
[0004] 2. Description of the Related Art
[0005] For example, a printed wiring board is disclosed in which
lands for grounding are disposed around fixing holes for bolting of
the printed wiring board. This printed wiring board is equipped
with a substrate, the fixing holes which penetrate through the
substrate, the lands which are donut-shaped and are formed around
the respective fixing holes on the surface of the substrate, and
cream solder members which are printed on the surfaces of the
lands.
[0006] In printed wiring boards of this type, usually, the surfaces
of the lands are subjected to solder plating to prevent corrosion
of the lands and attain reliable grounding. A printed wiring board
having a cost advantage over ones in which the lands are subjected
to solder plating is provided by supplying solder also to the land
surfaces when cream solder is supplied to mounting patterns of
other components (see JP-A-2000-244080, for instance).
[0007] In recent years, with the increase in miniaturization and
functionality of digital equipment, the high-density mounting on a
printed wiring board and the securing of a wide mounting area have
come to be required increasingly. However, the above donut-shaped
lands raise a problem that the mounting area on the printed wiring
board is reduced by areas corresponding to the spaces for formation
of the lands. For another thing, to secure a wide mounting area on
a printed wiring board, it is effective to locate the fixing holes
as close to the outer periphery of the board as possible. However,
in the printed wiring boards, the fixing holes cannot be located
sufficiently close to the outer periphery because margins for
formation of the donut-shaped lands need to be secured around the
respective fixing holes.
[0008] Each of these margins needs to be set taking into
consideration not only the space for formation of the land but also
a variation that may occur when a land pattern is formed by
etching. This is because it a land is formed in contact with the
periphery the land is exposed in an end face of the printed wiring
board, as a result of which the printed wiring board may be
short-circuited with another component. This also requires
sufficient margins around the respective fixing holes.
[0009] On the other hand, one method for reducing the above margins
is to narrow the widths of the donut-shaped lands. However, if the
land widths are narrowed, a land pattern may be disconnected due to
a variation in forming the pattern. Furthermore, since the lands
are reduced in strength, the land patterns are prone to peel off
when bolting is performed through the fixing holes.
[0010] For the above reasons, the printed wiring boards cannot
sufficiently satisfy the recent requirements of high-density
mounting and securing of a wider mounting area.
SUMMARY
[0011] According to an aspect of the invention, there is provided a
printed wiring board including: a substrate including an edge and a
fixing hole located adjacent to the edge, the fixing hole
configured to receive a bolt; and a land formed in a vicinity of
the fixing hole and extending in at least a first direction and a
second direction, the first direction being a direction from the
fixing hole toward a center of the substrate, the second direction
being direction along the edge.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] A general architecture that implements the various feature
of the present invention will now be described with reference to
the drawings. The drawings and the associated descriptions are
provided to illustrate embodiments of the present invention and not
to limit the scope of the present invention.
[0013] FIG. 1 is an exemplary perspective view of a portable
computer according to a first embodiment;
[0014] FIG. 2 is an exemplary sectional view, taken in a horizontal
plane, of a main body unit of the portable computer shown in FIG.
1;
[0015] FIG. 3 is an exemplary plan view of a printed wiring board
which is housed in a casing of the main body unit shown in FIG.
2;
[0016] FIG. 4 is an exemplary sectional view, taken in a vertical
plane, of the printed wiring board shown in FIG. 3;
[0017] FIG. 5 is an exemplary plan view of a printed wiring board
of a portable computer according to a modification of the first
embodiment;
[0018] FIG. 6 is an exemplary plan view of a printed wiring board
of a portable computer according to a second embodiment;
[0019] FIG. 7 is an exemplary sectional view, taken in a vertical
plane, of the printed wiring board shown in FIG. 6;
[0020] FIG. 8 is an exemplary plan view of a printed wiring board
of a portable computer according to a third embodiment;
[0021] FIG. 9 is an exemplary plan view of a printed wiring board
of a portable computer according to a fourth embodiment;
[0022] FIG. 10 is an exemplary perspective view of a printed wiring
board which is housed in a casing of a hard disk drive according to
a fifth embodiment; and
[0023] FIG. 11 is an exemplary sectional view, taken in a vertical
plane, of the printed wiring board shown in FIG. 10.
DETAILED DESCRIPTION
[0024] An electronic apparatus according to a first embodiment will
be described below with reference to FIGS. 1 to 4. As shown in FIG.
1, a portable computer as an example electronic apparatus is a
so-called notebook personal computer. A description will be made
with a notation that the forward direction and the backward
direction are denoted by arrows F and R, respectively.
[0025] As shown in FIG. 1, the portable computer 11 is equipped
with a main body unit 12, a display unit 13, and hinge mechanisms
14 which connect the main body unit 12 and the display unit 13.
Supporting the display unit 13, the hinge mechanisms 14 make it
possible to rotate the display unit 13 with respect to the main
body unit 12. The display unit 13 has a display 15 and a cover 16
surrounding the display 15. The display 15 is a liquid crystal
display, for example.
[0026] The main body unit 12 has a casing 21 made of a synthetic
resin, a keyboard 22, a touch pad 23 which is a pointing device,
and buttons 24. As shown in FIGS. 2 and 4, the main body unit 12
also has, inside the casing 21, a printed circuit board 25 and
bolts 26 for fixing of the printed circuit board 25 to the casing
21. The printed circuit board 25 has a printed wiring board 31 and
plural circuit components 32 which are mounted on the printed
wiring board 31. The plural circuit components 32 include a CPU and
a north bridge. The bolts 26 are not illustrated in FIG. 2. The
inside surfaces of the casing 21 are uniformly covered with a
conductive ground layer 46. The ground layer 46 prevents outward
leakage of electromagnetic waves from the portable computer 11.
[0027] For example, the printed wiring board 31 is a copper-clad
lamination plate in which plural copper wiring layers are
laminated. The printed wiring board 31 has a substrate 33 and a
land 34 which is formed on the substrate 33. The substrate 33 is
formed by alternately laminating insulating layers (base members)
made of a glass-cloth-incorporated resin and wiring layers
sandwiched between the insulating layers. The substrate 33 has a
first edge 35A and a second edge 35B which define part of the
periphery of the substrate 33, a fixing hole 36 which is located
adjacent to the first edge 35A and the second edge 35B, and a
conductive plating member 37 which covers the inside surface of the
fixing hole 36. The fixing hole 36 is located as close to the first
edge 35A and the second edge 35B as possible.
[0028] As shown in FIGS. 3 and 4, the plating member 37 is made of
a metal material, assumes a cylindrical shape, and is electrically
connected to a ground member 41 which is disposed inside the
substrate 33. The plating member 37 is continuous with and is
electrically connected to the land 34. The ground member 41 is
grounded to the ground layer 46 via the plating member 37 and the
bolt 26.
[0029] The substrate 33 has, in addition to the fixing hole 36,
through-holes 42 for bolting of the printed wiring board 31 to the
casing 21. A second land 43 having a conventional shape (i.e., a
donut shape) is formed around the opening of each through-hole 42.
When the printed circuit wiring 31 is fixed to the casing 21, the
bolts 26 are inserted through the fixing hole 36 and the
through-holes 42.
[0030] The substrate 33 has, on its top surface, a pair of first
regions 44 which extend along the respective edges 35 so as to
assume band shapes. The land 34 is formed around (in a vicinity of)
the fixing hole 36. The land 34 extends from the fixing hole 36 in
a range that is defined between a direction D1 from the fixing hole
36 toward a central portion 45 of the substrate 33 and directions
D2 along the respective edges 35. That is, the land 34 is
sector-shaped and is formed so as to extend toward the central
portion 45 of the substrate 33. An angle of the sector shape of the
land 34 is about 90 degrees. The land 34 is positioned outside the
first regions 44. For example, the land 34 is formed into the
sector shape by etching the surface copper foil layer of the
substrate 33.
[0031] Although in the embodiment the plural through-holes 42 and
the one fixing hole 36 are provided, the invention is not limited
to such a case; plural fixing holes 36 may be provided so as to
replace part of the through-holes 42. In the embodiment, the fixing
hole 36 is located adjacent to the two edges 35A and 35B, that is,
the corner edge, of the printed wiring board 31 and the
sector-shape angle of the land 34 is equal to about 90 degrees.
However, the invention is not limited to such a case. As shown in
FIG. 5, the fixing hole 36 may be located adjacent to one edge 35
of the printed wiring board 31, in which case the sector-shape
angle of the land 34 is equal to about 180 degrees (described later
in detail).
[0032] In the first embodiment, the printed wiring board 31 is
equipped with the substrate 33 having the edges 35 which define
part of the periphery of the printed wiring board 31 and the fixing
hole 36 which is located adjacent to the edges 35 and through which
the bolt 26 is inserted and the land 34 which is formed around the
fixing hole 36 and extends outward from the fixing hole 36 in the
range that is defined between the direction D1 going from the
fixing hole 36 toward the central portion 45 of the substrate 33
and the directions D2 that are along the edges 35.
[0033] With this structure, the land 34 is formed along the
direction D1 which goes toward the central portion 45 of the
substrate 33 and the land 34 is not formed between the fixing hole
36 and the edges 35. As a result, no space for formation of the
land 34 is required between the fixing hole 36 and the edges 35 and
hence the fixing hole 36 can be located as close to the edges 35 as
possible. Therefore, a wide mounting area can be secured on the
printed wiring board 31, which makes it possible to cope with the
miniaturization of the printed wiring board 31 flexibly.
Furthermore, since the land 34 need not be formed narrowly, a land
pattern can be made sufficiently strong. This prevents a phenomenon
that the land 34 is so weak that its pattern peels off when the
bolt 26 is inserted through the fixing hole 36 for the purpose of
fixing. Another problem can be prevented that a pattern of the land
34 is disconnected halfway when it is formed by etching.
[0034] The land 34 is formed outside the band-shaped first regions
44 which extend along the edges 35. This structure prevents a
problem that the land 34 is deviated to be exposed in an end face
of the printed wiring board 31. This makes it possible to locate
the fixing hole 36 even closer to the edges 35. Therefore, an even
wider mounting area can be secured on the printed wiring board
31.
[0035] The land 34 has the sector shape whose virtual apex is
located in the fixing hole 36, and extends toward the central
portion 45. With this structure, the land 34 is given sufficient
strength though it is simple in shape. In particular, since the
land 34 has the sector shape, the head of the bolt 26 can easily be
brought into contact with the land 34, whereby the printed wiring
board 31 can be grounded to the ground layer 46 of the casing 21
reliably.
[0036] In the embodiment, the printed wiring board 31 is provided
with the conductive plating member 37 which covers the inside
surface of the fixing hole 36 and is continuous with the land 34.
With this structure, the contact area between the bolt 26 and the
land 34/plating member 37 is increased, whereby the printed wiring
board 31 can be grounded to the ground layer 46 of the casing 21
more reliably.
[0037] A modification of the portable computer 11 according to the
first embodiment will be described below with reference to FIG. 5
(differences will be described mainly). In FIG. 5, members having
the same members in the first embodiment are given the same
reference symbols as the latter.
[0038] As shown in FIG. 5, a printed wiring board 31 has a
substrate 33 and a land 34 which is formed on the substrate 33. The
substrate 33 has an edge 35 which defines part of the periphery of
the substrate 33, a fixing hole 36 which is located adjacent to the
edge 35, and a conductive plating member 37 which covers the inside
surface of the fixing hole 36. The fixing hole 36 is located as
close to the edge 35 as possible.
[0039] The substrate 33 has, on its top surface, a pair of first
regions 44 which extend along the edge 35 so as to assume band
shapes. The land 34 is formed around (in the vicinity of) the
fixing hole 36. The land 34 extends outward from the fixing hole 36
in a range that is defined between a direction D1 going from the
fixing hole 36 toward a central portion 45 of the substrate 33 and
directions D2 that are along the edge 35. That is, the land 34 is
sector-shaped and is formed so as to extend toward the central
portion 45 of the substrate 33. The angle of the sector shape of
the land 34 is about 180 degrees. The land 34 is disposed outside
the first regions 44.
[0040] According to the modification of the first embodiment, a
wide mounting area can be secured on the printed wiring board 31
even in the case where the fixing hole 36 is located in the
vicinity of one edge 35. Furthermore, since the land 34 does not
overlap with the band-shaped first regions 44 which extend along
the edge 35, a phenomenon that the land 34 is deviated to be
exposed in an end face of the printed wiring board 31 can be
prevented.
[0041] Next, a portable computer according to a second embodiment
will be described with reference to FIGS. 6 and 7. The portable
computer 11 as an example electronic apparatus according to the
second embodiment is the same as that according to the first
embodiment except that a printed wiring board 51 is not provided
with the plating member 37 and through-hole plating members 52
which connect a land 34 to the ground member 41 are provided
separately from a fixing hole 36. Therefore, members that are
different than in the first embodiment will mainly be described
below, and members having the same members in the first embodiment
will be given the same reference symbols as the latter and will not
be described.
[0042] The printed wiring board 51 of the portable computer 11
according to the second embodiment has a substrate 33, the land 34
which is formed on the substrate 33, and the through-hole plating
members 52 which connect the land 34 to the ground member 41. The
through-hole plating members 52 are separate from the fixing hole
36. The substrate 33 has, on its top surface, a pair of first
regions 44 which extend along edges 35 so as to assume band shapes.
The land 34 is formed around (in the vicinity of) the fixing hole
36. The land 34 extends outward from the fixing hole 36 in a range
that is defined between a direction D1 going from the fixing hole
36 toward a central portion 45 of the substrate 33 and directions
D2 that are along the edges 35. That is, the land 34 is
sector-shaped and is formed so as to extend toward the central
portion 45 of the substrate 33. The angle of the sector shape of
the land 34 is about 90 degrees. The land 34 does not overlap with
the first regions 44.
[0043] According to the second embodiment, a wide mounting area can
be secured on the printed wiring board 51 as in the first
embodiment even in the case where the plating member 37 is not
provided. Furthermore, a manufacturing process can be made simpler
than in the printed wiring board 31 according to the first
embodiment by a degree corresponding to the elimination of the
plating member 37.
[0044] Next, a portable computer according to a third embodiment
will be described with reference to FIG. 8. The portable computer
11 as an example electronic apparatus according to the third
embodiment is the same as that according to the first embodiment
except for the shape of a land 72 of a printed wiring board 71.
Therefore, members that are different than in the first embodiment
will mainly be described below, and members having the same members
in the first embodiment will be given the same reference symbols as
the latter and will not be described.
[0045] The printed wiring board 71 of the portable computer 11
according to the third embodiment has a substrate 33 and the land
72 which is formed on the substrate 33. The substrate 33 has, on
its top surface, a pair of first regions 44 which extend along
edges 35 so as to assume band shapes. The land 72 is formed around
(in the vicinity of) the opening of a fixing hole 36. The land 72
extends outward from the fixing hole 36 in a range that is defined
between a direction D1 going from the fixing hole 36 toward a
central portion 45 of the substrate 33 and directions D2 that are
along the edges 35. The land 72 is disposed outside the first
regions 44 or a second region 73 that is located between the fixing
hole 36 and the central portion 45. More specifically, the land 72
extends outward from the fixing hole 36 in two directions that are
along the edges 35 so as to generally assume an L shape as a whole.
The land 72 is continuous with a plating member 37.
[0046] In the third embodiment, the land 72 is disposed outside the
second region 73 which is located between the fixing hole 36 and
the central portion 45. With this structure, the second region 73
can be used as a mounting area; for example, interconnections and
circuit components can be disposed in the second region 73.
Therefore, a wider mounting area can be secured on the printed
wiring board 71 than even on the printed wiring board 31 of the
first embodiment. Furthermore, since a pattern of the land 72 is
formed by, for example, etching a copper foil, the manufacturing
process is not made more complex than in the first embodiment.
[0047] Next, a portable computer according to a fourth embodiment
will be described with reference to FIG. 9. The portable computer
11 as an example electronic apparatus according to the fourth
embodiment is the same as that according to the second embodiment
except for the shape of lands 82 of a printed wiring board 81.
Therefore, members that are different than in the second embodiment
will mainly be described below, and members having the same members
in the second embodiment will be given the same reference symbols
as the latter and will not be described.
[0048] The printed wiring board 81 of the portable computer 11
according to the fourth embodiment has a substrate 33, the lands 82
which are formed on the substrate 33, and through-hole plating
members 52 which connect the respective lands 82 to a ground member
41. The substrate 33 has, on its top surface, a pair of first
regions 44 which extend along edges 35 so as to assume band shapes.
The lands 82 are formed around (in the vicinity of) the opening of
a fixing hole 36. The lands 82 extend outward from the fixing hole
36 in a range that is defined between a direction D1 going from the
fixing hole 36 toward a central portion 45 of the substrate 33 and
directions D2 that are along the edges 35. The lands 82 are
disposed outside the associated first regions 44.
[0049] The land 82 is located outside a second region 73 that is
located between the fixing hole 36 and the central portion 45. More
specifically, the lands 72 extend outward from the fixing hole 36
in two respective directions that are along the edges 35. In this
embodiment, the lands 82 are disposed separately at the two
positions around the fixing hole 36.
[0050] In the fourth embodiment, the lands 82 do not overlap with
the second region 73 which is located between the fixing hole 36
and the central portion 45. With this structure, as in the third
embodiment, a wider mounting area can be secured on the printed
wiring board 81 than even on the printed wiring board 51 of the
second embodiment. Furthermore, the manufacturing process is not
made more complex than in the second embodiment even if the lands
82 have the above-described shapes.
[0051] Next, an electronic apparatus according to a fifth
embodiment will be described with reference to FIGS. 10 and 11. The
fifth embodiment is directed to a case that the invention is
applied to a hard disk drive 91 which is an example electronic
apparatus. Although individual components of the hard disk drive 91
are different in structure than in the first to fourth embodiments,
the structure of a printed wiring board 51 is approximately the
same as in the second embodiment. Therefore, members that are
different than in the second embodiment will mainly be described
below, and members having the same members in the second embodiment
will be given the same reference symbols as the latter and will not
be described.
[0052] The hard disk drive 91 is equipped with a casing 21, a
printed circuit board 25 which is housed in the casing 21, a
housing 92 which houses plural disks, a spindle motor 93 for
rotationally driving the plural disks, and other components. The
hard disk drive 91 also has bolts 26 (not shown in FIG. 10) for
fixing of the printed circuit board 25 to the casing 21. The
printed circuit board 25 has the printed wiring board 51 and plural
circuit components (not shown in FIGS. 10 and 11) which are
disposed on the printed wiring board 51.
[0053] The printed wiring board 51 is different from that of the
second embodiment in that the former has an opening 94 where the
spindle motor 93 is disposed, they are the same in structure in the
other points. A substrate 33 of the printed wiring board 51 has one
fixing hole 36 around which a sector-shaped land 34 is formed and
two through-holes 42 around which donut-shaped second lands 43 are
formed, respectively. The land 34 is the same as that of the second
embodiment.
[0054] According to the fifth embodiment, even in the hard disk
drive 91 which is an example electronic apparatus, the fixing hole
36 can be located as close to the edges 35 as possible and hence a
wide mounting area can be secured on the printed wiring board 51.
This makes it possible to cope with the miniaturization of the
printed wiring board 51 flexibly and to thereby miniaturize the
hard disk drive 91 as a whole.
[0055] Although the printed wiring board 51 of the fifth embodiment
is similar to that of the second embodiment, this aspect of the
invention is not limited to such a case. That is, a printed wiring
board similar to the printed wiring board of the first, third, or
fourth embodiment may be used.
[0056] The electronic apparatus according to the invention is not
limited to portable computers and hard disk drives, and the
invention can also be applied to other kinds of electronic
apparatus such as a cell phone. Other various modifications can be
made of the above-described electronic apparatus without departing
from the spirit and scope of the invention.
* * * * *