U.S. patent application number 10/303936 was filed with the patent office on 2003-05-15 for resin substrate.
This patent application is currently assigned to NGK Spark Plug Co., Ltd.. Invention is credited to Itai, Motohiko, Saiki, Hajime.
Application Number | 20030089524 10/303936 |
Document ID | / |
Family ID | 11972733 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030089524 |
Kind Code |
A1 |
Saiki, Hajime ; et
al. |
May 15, 2003 |
Resin substrate
Abstract
A resin substrate is made of resin or a composite material
containing resin. Pins each having the surface, on which Au plating
is formed, are, with a soldering material made of Sn and Sb,
soldered to a substrate body having a first main surface and formed
into substantially a rectangular shape to project over the first
main surface 2A of the substrate body. Wettability of the soldering
material for securing the pins and the substrate body to one
another is relatively low as compared with that of a Pb--Sn
soldering material. Therefore, the height of upward movement of the
soldering material along the pin can be reduced. Hence it follows
that the pins can sufficiently deeply be inserted into the socket
so that the gap between the first main surface of the substrate
body and the upper surface of the socket is reduced. As a result,
the overall height realized after the substrate made of resin has
been joined to the socket can be reduced
Inventors: |
Saiki, Hajime; (Niwa-gun,
JP) ; Itai, Motohiko; (Kani-shi, JP) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
NGK Spark Plug Co., Ltd.
|
Family ID: |
11972733 |
Appl. No.: |
10/303936 |
Filed: |
November 26, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10303936 |
Nov 26, 2002 |
|
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09476988 |
Jan 4, 2000 |
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6518518 |
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Current U.S.
Class: |
174/267 ;
174/257; 439/876 |
Current CPC
Class: |
H01L 2224/29099
20130101; H01L 2924/00 20130101; H01L 2924/01322 20130101; H01R
12/52 20130101; B23K 35/262 20130101; H01L 2224/81191 20130101;
H01R 13/405 20130101; H01L 2224/81899 20130101; H01R 12/718
20130101; H01L 2924/01322 20130101; H01L 2924/00013 20130101; H01L
2224/81141 20130101; H05K 3/3463 20130101; H01L 2924/00013
20130101 |
Class at
Publication: |
174/267 ;
174/257; 439/876 |
International
Class: |
H01R 012/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 27, 1999 |
JP |
P.HEI. 11-018477 |
Claims
What is claimed is:
1. A resin substrate comprising: a substrate body made of resin or
a composite material containing resin and formed into a plate-like
shape which has a first main surface; and a pin having a surface on
which an Au-plated layer is formed; wherein said pin is soldered to
said substrate body with a soldering material comprising Sn and Sb
so as to be projected over said first main surface of said
substrate body.
2. The resin substrate according to claim 1, wherein the height of
said pin projecting over said first main surface is 2 mm or
smaller.
3. The resin substrate according to claim 2, wherein the thickness
of said Au-plated layer of said pin is 0.04 .mu.m or larger.
4. The resin substrate according to claim 2, wherein the quantity
of Sb contained in said soldering material is 15 wt % or
smaller.
5. The resin substrate according to claim 3, wherein the quantity
of Sb contained in said soldering material is 15 wt % or
smaller.
6. The resin substrate according to claim 2, wherein said soldering
material has a melting point of 280.degree. C. or lower.
7. The resin substrate according to claim 3, wherein said soldering
material has a melting point of 280.degree. C. or lower.
8. The resin substrate according to claim 1, wherein said soldering
material further comprises at least one of Ag, Bi, Au, Pb, In, Al,
As.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a resin substrate, which
has a substrate body and a pin serving as an input/output terminal,
and more particularly to a resin substrate having a pin which can
reliably be connected to a socket or another substrate.
[0003] 2. Description of the Related Art
[0004] Conventionally, a structure has been known in which a pin
serving as an input/output terminal is secured and stood erect on a
substrate body made of an insulating material, such as resin, for
example, epoxy resin, or composite material of the resin and glass
fibers, the pin being secured and stood erect by using a Pb--Sn
soldering material, such as Pb--Sn eutectic solder.
[0005] As the foregoing resin substrate, a resin substrate 101
structured, for example, as shown in FIG. 6 is exemplified. A
substrate body 102 of the resin substrate 101 has a resin
insulating layer 103 and a circuit layer (not shown). A first main
surface 102A of the resin substrate 101 has a connection pad 104
formed thereon. A solder resist layer 105 is formed to reach the
edge of the connection pad 104.
[0006] The pin 111 has a large-diameter portion 111A and a shaft
portion 111b and having a structure that the overall surface is
applied with Ni plating or Au plating (not shown). The
large-diameter portion 111A of the pin 111 is secured with a
soldering material 115 to be opposite to the connection pad 104
allowed to expose over the solder resist layer 105. The soldering
material 115 for establishing the connection between the pin 111
and the substrate body 102 is welded to substantially the overall
surface of the exposed connection pad 104 and portions of the
large-diameter portion 111A and the shaft portion 111b such that
the soldering material 115 forms substantially a truncated-cone
fillet shape.
[0007] When the resin substrate 101 has been joined to the socket,
a large gap DSA is formed between the first main surface 102A of
the substrate body 102 and the upper surface SKA of the socket SK,
for example, as shown in FIG. 7. When the resin substrate 101 is
mounted on another substrate or the like, also a large gap is
formed. The reason for this lies in that the soldering material 115
upwards moved and welded to the shaft portion 111b of the pin 111
when the pin 111 is soldered to the substrate body 102
substantially enlarges the diameter of the shaft portion 111b of
the pin 111. Thus, the shaft portion 111B cannot sufficiently
deeply be inserted into the socket SK or a through hole of the
other substrate.
[0008] If the large gap is formed, the overall height realized
after the resin substrate 101 has been joined to the socket SK or
the like is enlarged excessively. Thus, a requirement for reducing
the height cannot be met. The pin 111 of a type which projects over
the first main surface 102A by a short length sometimes suffers
from unsatisfactory reliability of the connection with the socket
SK or the like. Moreover, a requirement for connecting the
substrate made of the resin 101 and the socket SK or the other
substrate to each other for a shortest distance cannot be met.
[0009] As the wettability between the soldering material 115 and
the Au-plated layer on the surface of the pin 111 is improved, the
height HSA of the soldering material 115 which upwards moves when
the pin 111 is secured is enlarged. When the wettability is
adjusted to reduce the height HSA of the soldering material 115
which upwards moves, it can be considered that the overall height
realized after the resin substrate 101 has been joined to the
socket SK or the like can be reduced.
SUMMARY OF THE INVNETION
[0010] It is an object of the present invention to provide a resin
substrate with which the gap between the substrate body and another
substrate or the like can be reduced when the resin substrate
having a multiplicity of pins serving as input/output terminals and
stood erect is joined to a socket or another substrate.
[0011] According to the present invention, there is provided a
resin substrate, comprising: a substrate body made of resin or a
composite material containing resin and formed into a plate-like
shape which has a first main surface; and a pin having a surface on
which an Au-plated layer is formed, wherein the pin is soldered to
the substrate body with a soldering material mainly composed of Sn
and Sb so as to be projected over the first main surface of the
substrate body.
[0012] The present invention has the structure that the soldering
material for securing the pin and the substrate body to each other
is the soldering material mainly composed of Sn and Sb. The
foregoing soldering material becomes wet with Au plating on the
surface of the pin. The wettability is inferior to the Pb--Sn
soldering material. Therefore, the foregoing soldering material,
which is capable of soldering the pin to the substrate body, does
not considerably upwards move along the pin.
[0013] Therefore, the portions to which the solder is welded and,
the diameter of each of which is enlarged can be decreased. Hence
it follows that the pin can sufficiently deeply be inserted into
the socket or the through hole of another substrate. Therefore, the
gap between the first main surface of the substrate body and the
socket or the other substrate can be reduced. As a result, the
overall height realized after the resin substrate has been joined
to the socket or the like can be reduced.
[0014] The substrate body may be made of resin, such as epoxy
resin, or an insulating material made of a composite material of
the foregoing resin and glass fibers. The substrate body includes a
laminated circuit substrate having a core substrate, on either side
or two sides of which insulating layers and circuit layers are
alternately laminated. As an alternative to this, a laminated
circuit substrate having no core substrate and having the foregoing
laminated structure is included.
[0015] The pin must have the surface on which the Au-plated layer
is formed. The bonding strength of the substrate body or the like
must be considered to arbitrary select the pin. The pin may be a
pin in the form of the head of a nail or a pin having a
large-diameter portion in an intermediate portion thereof. The
material of the pin is exemplified by metal, such as covar, a
42NI--Fe alloy or a copper alloy. It is preferable that a Ni-plated
layer is formed as the base layer for the Au-plated layer.
[0016] The soldering material must mainly be made of Sn and Sb. In
consideration of the melting point and the bonding strength, the
quantity of the foregoing elements must be determined. In addition
to the elements, such as Sn and Sb, Ag, Bi, Au, Pb, In, Al, As or
the like may be added in a small quantity.
[0017] In the present invention, it is preferable that the height
of the pin projecting over the first main surface is 2 mm or
smaller.
[0018] If the length of the pin projecting over the first main
surface of the substrate body is too short, that is, if the length
is 2 mm or smaller, the portion of the pin which can be inserted
into the socket or the through hole of the substrate is too short
to reliably connect the resin substrate to the socket or the like
when upward movement of the soldering material takes place greatly.
If the connector of the socket is brought into contact with the
soldering material which covers the pin, the reliability of the
connection sometimes deteriorates as compared with the reliability
realized when the contact with the Au-plated layer is made.
[0019] The present invention, which is arranged to use the
soldering material mainly composed of Sn and Sb having a poor
wettability with the pin as compared with the Pb--Sn soldering
material, is able to prevent upward movement of the soldering
material which occurs when the pin is secured. Although the portion
of the pin which projects over the substrate body is short, a
sufficiently long portion of the pin which is inserted into the
socket or the through hole of the other substrate can be
maintained. As a result, the resin substrate can reliably be
connected to another substrate or the like.
[0020] In the present invention, it is preferable that the
thickness of the Au-plate layer of the pin is 0.04 m or larger.
[0021] If the thickness of the Au-plated layer on the surface of
the pin is enlarged, the soldering material is easily wetted. Thus,
the height realized by the upward movement is enlarged. Therefore,
when a soldering material, such as a Pb--Sn soldering material,
having considerable wettability is used, the thickness of the
Au-plated layer cannot be enlarged.
[0022] On the other hand, the present invention arranged to use the
Sn--Sb soldering material and having poor wettability is able to
prevent upward movement if the Au-plated layer having a large
thickness is formed. Therefore, the Au-plated layer having a large
thickness of 0.04 .mu.m or larger, for example, 0.05 .mu.m or 0.1
.mu.m, can be formed to maintain the antioxidation characteristic
and reliability of the connection with the socket or the like.
[0023] In the present invention, it is preferable that the quantity
of Sb contained in the soldering material is 15 wt % or lower.
[0024] If the melting point of the strength material is too high,
the operation for soldering the pin to the substrate body sometimes
encounters deterioration in the characteristics of the substrate
body, in particular, the resin insulating layer, at the soldering
temperature according to the material. Moreover, the substrate body
is sometimes decolored.
[0025] According to the present invention, the soldering material
is mainly composed of Sn and Sb and arranged to contain Sb by 15 wt
% or smaller. Therefore, the melting point of the soldering
material is 280.degree. C. or lower. Hence it follows that the pin
can be soldered to the substrate body at a low soldering
temperature. As a result, a material having excellent heat
resistance is not required when the soldering operation is
performed. Thus, reliable connection can be performed without any
deterioration in the characteristics of the substrate body.
Moreover, decoloration of the substrate body can be prevented or
restrained. Since wettability required to secure the pin and the
substrate body to each other can sufficiently be maintained, the
reliability of the connection between the pin and the substrate
body can be improved.
[0026] In the present invention, it is preferable that the quantity
of Sb contained in the soldering material is not less than 3 wt %
nor more than 15 wt %.
[0027] When the quantity of Sb contained in the Sn--Sb soldering
material is 3 wt % or larger, deterioration in the wettability of
the soldering material apparently occurs. Therefore, when the
quantity of contained Sb is 3 wt % or larger, upward movement of
the soldering material which takes place when the pin is secured
can reliably be prevented. Hence it follows that manufacturing
yield of the resin substrate can furthermore be improved.
[0028] In the present invention, it is preferable that the melting
point of the soldering material is 280.degree. C. or lower.
[0029] As described above, if the melting point of the strength
material is too high, the operation for soldering the pin to the
substrate body sometimes encounters deterioration in the
characteristics of the substrate body, in particular, the resin
insulating layer, at the soldering temperature according to the
material. Moreover, the substrate body is sometimes decolored.
[0030] Since the present invention is structured such that the
melting point of the soldering material is 280.degree. C. or lower,
a material having excellent heat resistance is not required when
the pin is secured to prevent or restrain deterioration in the
characteristics of the substrate body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In the accompanying drawings:
[0032] FIG. 1 is a partially-enlarged cross sectional view showing
a resin substrate according to embodiments 1 to 3;
[0033] FIG. 2 is a partially-enlarged cross sectional view showing
a state in which the resin substrate according to embodiments 1 to
3 has been joined to a socket;
[0034] FIGS. 3A to 3C are diagrams showing a method of
manufacturing the resin substrate according to embodiments 1 to 3,
FIG. 3A showing the substrate body, FIG. 3B showing a state in
which a solder ball has been placed on the substrate body and FIG.
3C showing a state in which the pin has been secured to the
substrate body;
[0035] FIG. 4 is a partially-enlarged cross sectional view showing
a resin substrate according to embodiments 4 to 6;
[0036] FIG. 5 is a partially-enlarged cross sectional view showing
a state in which the resin substrate according to embodiments 4 to
6 has been joined to the other substrate;
[0037] FIG. 6 is a partially-enlarged cross sectional view showing
a conventional substrate; and
[0038] FIG. 7 is a partially-enlarged cross sectional view showing
a state in which the conventional substrate has been joined to a
socket.
PREFERRED EMBODIMENTS OF THE INVENTION
[0039] (Embodiments 1, 2 and 3)
[0040] Preferred embodiments of the present invention will now be
described with reference to the drawings.
[0041] A resin substrate according to the present invention is
shown in FIG. 1 which is a partially-enlarged cross sectional
view.
[0042] The substrate 1 made of resin has a substrate body 2 formed
into substantially a rectangular shape having size of 32
mm.times.36 mm and a thickness of 1 mm. A first main surface 2A of
the substrate body 2 has a nail-head-shape pins 11 serving as
input/output terminals stood erect to form a lattice configuration
by using a soldering material 15 made of Sn--Sb. Embodiments 1, 2
and 3 have the same structure except for the different soldering
materials 15. Embodiment 1 is arranged to use a soldering material
(having a melting point of 240.degree. C.) made of 95Sn--5Sb,
embodiment 2 is arranged to use a soldering material (having a
melting point of 235.degree. C.) made of 98Sn--2Sb and embodiment 3
is arranged to use a soldering material (having a melting point of
315.degree. C.) made of 80Sn--20Sb.
[0043] The substrate body 2 has a resin insulating layer 3 made of
epoxy resin and a circuit layer (not shown) made of copper. The
first main surface 2A has a connection pad 4 made of copper. An
opening 6 (having a diameter of 0.65 mm) is formed to reach the
edge of the connection pad 4. Moreover, a solder resist layer 5
(having a thickness of 20 .mu.m) made of epoxy resin is formed.
[0044] On the other hand, the pin is made of covar and having a
nail-head-shape large-diameter portion 11A (having a diameter of
0.6 mm and a height of 0.1 mm) and a shaft portion 11B (having a
diameter of 0.38 mm and a height (a length) of 0.95 mm). A Ni--P
plated layer 12 having a thickness of 2 .mu.M is formed on the
overall surface of the pin 11. Moreover, an Au-plated layer 13
having a thickness of 0.05 .mu.m is formed on the surface of the
Ni--P plating layer 12. When a manufacturing process is performed,
contact of the soldering material 15 with the Au-plated layer 13
causes the Au plating 13 to be dissolved and dispersed in the
soldering material 15. Therefore, the soldering material 15 is
welded to the Ni--P plating 12 in the portions of the surface of
the pin 11 to which the soldering material 15 has been welded.
[0045] The substrate body 2 and the pin 11 are secured to each
other with the soldering material 15 such that the large-diameter
portion 11A of the pin 11 is positioned opposite to the connection
pad 4 exposed to the outside over the solder resist layer 5 of the
substrate body 2. The height PS of projection of the pin 11 when
viewed from the first main surface is 1 mm. The soldering material
15 is welded to substantially the overall surface of the exposed
connection pad 4, the overall body of an engaging portion 11A of
the pin 11 and a portion (an upper portion in the drawing) of the
shaft portion 11B such that a moderate circular truncated cone
fillet shape is formed. The height HS of upward movement of the
welded soldering material 15 over the connection pad 4 is 0.25 mm
in embodiment 1, 0.35 mm in embodiment 2 and 0.06 mm in embodiment
3.
[0046] FIG. 2 is a partially-enlarged cross sectional view showing
a state in which the substrate 1 made of resin has been joined to a
socket ST.
[0047] The socket ST has an upper surface STA in which a
multiplicity of blind holes BL are formed at positions
corresponding to the positions of the pins 11 of the substrate 1
made of resin. Moreover, the socket ST has contacts SSA for
securing the shaft portions 11B of the pins 11 inserted into the
blind holes BL; and terminals SSB molded integrally with the
contacts SSA and allowed to project over a lower surface STB of the
socket.
[0048] The terminals SSB projecting over the lower surface STB of
the socket ST are inserted into through via conductors of another
substrate WT so as to be secured by using a soldering material
HD.
[0049] The height HS of upward movement of the soldering material
15, the appearance of the substrate 1 made of resin and the like
were examined as follows.
[0050] The height HS of upward movement of the soldering material
15 of the substrate 1 made of resin according to each of
embodiments 1, 2 and 3 was measured. Thus, average values of five
samples were obtained. Moreover, the appearance of the resin
substrate 1 to which the pins 11 have been soldered was inspected.
As comparative examples, substrates made of resin which were the
same as those according to the embodiment except for the soldering
materials were manufactured. Then, the height HS of upward movement
and the appearance were similarly measured and inspected.
[0051] Results of measurement were collectively shown in Table
1.
1 TABLE 1 Point of Temperature Soldering of Soldering Compo- HS
Material Material nent (mm) (.degree. C.) (.degree. C.) Appearance
Embodiment 95Sn5Sb 0.25 240 250 satisfactory 1 Embodiment 98Sn2Sb
0.35 235 245 satisfactory 2 Embodiment 80Sn20Sb 0.06 315 325
deteriorated 3 Comparative 37Pb63Sn 0.84 183 210 satisfactory
Example 1 Comparative 50Pb50Sn 0.74 226 236 satisfactory Example
2
[0052] As can be understood from Table 1, the height HS of upward
movement of the soldering material 15 which was Sn--Sb soldering
material according to embodiments 1, 2 and 3 was 0.25 mm in
embodiment 1, 0.35 mm in embodiment 2 and 0.06 mm in embodiment 3.
As compared with comparative examples (0.84 mm in Comparative
Example 1 and 0.74 mm in Comparative Example 2) arranged to use the
Pb--Sn soldering material, the height HS of upward movement was
reduced. In particular, embodiments 1 and 3 containing Sb by 3 wt %
or larger were able to reduce the height HS of upward movement of
the soldering material 15.
[0053] On the other hand, Comparative Examples 1 and 2 arranged to
use the Pb--Sn soldering material encountered a fact that a major
portion of projection of each pin was wetted with the solder.
Therefore, the length of each pin which can be inserted into the
socket is insufficiently short. Hence it follows that the resin
substrate cannot reliably be joined to the socket.
[0054] Note that embodiment 3 encountered a fact that the substrate
body was partially decolored and the insulating layer deteriorated.
The substrates made of resin except for embodiment 3 has the
structures that the melting point of the soldering material is
240.degree. C. in embodiment 1, 235.degree. C. in embodiment 2,
183.degree. C. in Comparative Example 1 and 226.degree. C. in
Comparative Example 2. The foregoing temperatures were relatively
low temperatures which were 280.degree. C. or lower. Also the
soldering temperatures are somewhat higher than the melting points
by about 10.degree. C. On the other hand, embodiment 3 is arranged
to use the soldering material having the melting point which is
315.degree. C. and arranged to perform soldering at 325.degree. C.
Thus, the temperatures are high as described above. When a
substrate body made of a material, such as polyimide, having
excellent heat resistance is employed, decoloration of the
substrate body and deterioration in the insulating layer do not
occur if the soldering material (80Sn--20Sb) according to
embodiment 3 is employed.
[0055] As described above, the substrate 1 made of resin according
to embodiments 1, 2 and 3 has the structure that the soldering
material 15 for securing the pins 11 and the substrate body 2 is
made of Sn--Sb. Therefore, low wettability can be realized as
compared with the Pb--Sn soldering material. Therefore, the height
HS of upward movement of the soldering material 15 can be reduced.
In particular, the quantity of contained Sb is 3 wt % or larger
such that the quantity is 5 wt % in embodiment 1 and 20 wt % in
embodiment 3. Therefore, the height HS of upward movement of the
soldering material can furthermore be reduced.
[0056] Therefore, the pins 11 can sufficiently deeply be inserted
into the socket ST. Thus, gap DS between the first main surface 2A
of the substrate body 2 and the upper surface STA of the socket ST
can be reduced. Therefore, the overall height realized after the
substrate 1 made of resin has been joined to the socket ST can be
reduced.
[0057] The length (projection length) PS of the pin 11 projecting
over the first main surface 2A is a short length of 1 mm. However,
also the height HS of upward movement of the soldering material 15
is reduced such that the HS is 0.25 mm in embodiments 1, 0.35 mm in
embodiments 2 and 0.6 mm in embodiments 3. Therefore, the diameter
of the shaft portion 11B can be enlarged, causing the portion which
cannot be inserted into the socket ST to be reduced. As a result,
the substrate 1 made of resin can reliably be connected to the
socket ST.
[0058] Since the Au-plated layer 13 formed on the surface of the
pin 11 has a large thickness of 0.05 .mu.m, the antioxidation
characteristic and reliability of the connection with the socket ST
(the contact SSA) can be improved.
[0059] The quantity of Sb contained in the soldering material 15 is
15 wt % or smaller such that the quantity was 5 wt % in embodiment
1 and 2 wt % in embodiment 2. Moreover, the melting point of the
soldering material 15 is 280.degree. C. or lower such that the
melting point was 240.degree. C. in embodiment 1 and 235.degree. C.
in embodiment 2. Therefore, a material having excellent heat
resistance is not required to prevent decoloration of the resin
insulating layer 3 and the solder resist layer 5 and deterioration
in the insulating characteristic when soldering is performed.
[0060] A method of manufacturing the substrate 1 made of resin will
now be described with reference to FIGS. 3A to 3C.
[0061] Initially, the substrate body 2 shown in FIG. 3A is
manufactured. That is, a known method is employed to form the resin
insulating layer 3. Then, the solder resist layer 5 is formed such
that the connection pad 4 is exposed over the first main surface
2A.
[0062] Then, as shown in FIG. 3B, a solder ball 15A made of Sn--Sb
soldering material (95Sn--5Sb in embodiment 1, 98Sn--2Sb in
embodiment 2 and 80Sn--20Sb in embodiment 3) is placed on the
connection pad 4 of the first main surface 2A. Moreover, the pin 11
applied with the Ni--P plating 12 and the Au plating 13 is
prepared. Then, the solder ball 15A is heated and melted at a
temperature higher than the melting point of the soldering material
by about 10.degree. C. for one minute. As shown in FIG. 3C,
portions of the large-diameter portion 11A and the shaft portion
11B of the pin 11 adjacent to the connection pad 4 are secured to
the substrate body 2. Thus, the substrate 1 made of resin according
to this embodiment is manufactured.
[0063] The soldering material 15 is wetted by the shaft portion 11B
of the pin 11 which is applied with the Au plating 13 so as to be
formed into a moderate fillet shape having a relatively low height
HS of upward movement. The Au-plated layer 13 made contact with the
soldering material 15 is melted and dispersed in the soldering
material 15 in a very short time. Therefore, the soldering material
15 is welded to the Ni--P-plated layer 12 of the pin 11, as shown
in FIG. 1.
[0064] (Embodiments 4, 5 and 6)
[0065] Embodiments 4, 5 and 6 will now be described with reference
to FIG. 4. A substrate 21 made of resin according to embodiments 4,
5 and 6 is different from embodiments 1, 2 and 3 in that a
nail-head-shape pin 31 penetrates the substrate body 22 from the
second main surface 22B to the first main surface 22A. The other
structures are the same as embodiments 1, 2 and 3. Therefore,
similar portions to those of embodiments 1, 2 and 3 are omitted
from description or described simply.
[0066] The substrate 21 made of resin has a substrate body 22
formed into substantially a rectangular shape and having a
multiplicity of nail-head-shape pins 31 in the lattice-like
configuration by using a soldering material 35 made of Sn--Sb.
Embodiments 4, 5 and 6 are different from one another in only the
soldering materials 35. The other portions are the same. A
soldering material (having a melting point of 240.degree. C.) made
of 95Sn--5Sb is employed in embodiment 4, a soldering material
(having a melting point of 235.degree. C.) made of 98Sn--2Sb is
employed in embodiment 5 and a soldering material (having a melting
point of 315.degree. C.) made of 80Sn--20Sb is employed in
embodiment 6.
[0067] The substrate body 22 has a resin insulating layer 23 and
solder resist layers 25 and 29. The resin insulating layer 23 has a
through hole 36 formed from the lower surface 23A to the upper
surface 23B. Moreover, a through via conductor 37 is formed in the
inner wall of the through hole 36. A first connection pad 24 is
formed around the through hole 36 at a position on the lower
surface 23A. A solder resist layer 25 having an opening 26 is
formed to reach the first connection pad 24. On the other hand, a
circuit layer 27 is provided for the upper surface 23B. A solder
resist layer 29 having an opening 30 is formed in the portion of
the second connection pad 28 formed around the through hole 36.
[0068] On the other hand, the pin 31 is made of covar and having a
nail-head-shape large-diameter portion 31A (having a diameter of
0.6 mm and a height of 0.1 mm) and a shaft portion 31B (having a
diameter of 0.38 mm and a height (a length) of 2 mm. A Ni--P-plated
layer 32 having a thickness of 2 .mu.m is formed on the overall
surface of the pin 31. Moreover, an Au-plated layer 33 having a
thickness of 0.05 .mu.m is formed on the Ni--P-plated layer 32.
Similarly to embodiments 1, 2 and 3, portions of the surface of the
pin 31 to which the soldering material 35 has been welded are
welded to the Ni--P-plated layer 32.
[0069] The pin 31 is soldered while the large-diameter portion 31A
is being engaged to the second connection pad 28. The shaft portion
31B penetrates the through via conductor 37 to project downwards
over the first main surface 22A so as to be soldered to the through
via conductor 37 and the first connection pad 24. Thus, the pins 31
are secured to the substrate body 22. The portion of the soldering
material 35 welded to the portion of the first connection pad 24
and the shaft portion 31B of the pin 31 is formed into a moderate
fillet shape in the form of a circular truncated cone shape. The
height HS of upward movement of the welded soldering material 35
over the first connection pad 24 is 0.22 mm in embodiment 4, 0.33
mm in embodiment 5, and 0.05 mm in embodiment 6. Note that the
height PS of projection of the pin 31 over the first main surface
22A is 1 mm.
[0070] FIG. 5 is a partially enlarged cross sectional view showing
a state in which the substrate 21 made of resin has been joined to
another substrate WB. The substrate WB has a multiplicity of
through holes TH corresponding to the positions of the pins 31 of
the substrate 21 made of resin. A cylindrical conductor layer TD
having a through hole TDH is formed in the inner wall of the
through holes TH and around the through holes TH of the upper and
lower main surfaces WBA and WBB. A portion of the shaft portion 31B
of the pin 31 is inserted into the through hole TDH of the other
substrate WB so as to be soldered. Thus, the substrate 21 made of
resin is connected to the other substrate WB.
[0071] The height HS of upward movement of the soldering material
35, the appearance of the substrate 21 made of resin and the like
were examined as follows.
[0072] The height HS of upward movement of the soldering material
35 of the substrates 21 made of resin according to embodiments 4, 5
and 6 having the structures that the compositions of the soldering
materials 35 were different from one another was measured. An
average value of five samples was obtained. Also the appearance of
the substrate 21 made of resin was inspected. As comparative
examples, substrates made of resin were manufactured which were the
same as those according to embodiments 4, 5 and 6 except for the
soldering materials to perform similar measurement and
inspection.
[0073] Results of the measurement were shown in Table 2.
2TABLE 2 Melting Temper- Point of ature of Soldering Soldering HS
Material Material Component (mm) (.degree. C.) (.degree. C.)
Appearance Embodiment 95Sn5Sb 0.22 240 250 satisfactory 4
Embodiment 98Sn2Sb 0.33 235 245 satisfactory 5 Embodiment 80Sn20Sb
0.05 315 325 deteriorated 6 Comparative 37Pb63Sn 0.81 183 210
satisfactory Example 3 Comparative 50Pb50Sn 0.70 226 236
satisfactory Example 4
[0074] As can be understood from Table 2, similarly to the
foregoing inspection, the resin substrate (according to embodiments
4, 5 and 6) arranged to use the Sn--Sb soldering material is able
to reduce the height HS of upward movement of the soldering
material as compared with Comparative Examples 3 and 4 arranged to
use the Pb--Sn soldering material. In particular, embodiments 4 and
6 arranged to contain Sb by 3 wt % or larger are able to reduce the
height HS of upward movement of the soldering material.
[0075] On the other hand, Comparative Examples 3 and 4 arranged to
use the Pb--Sn soldering material encounter wetting of a major
portion of projection of the pin with the solder. Therefore, the
shaft portion of the present invention cannot sufficiently deeply
be inserted into the through hole TDH of the other substrate
WB.
[0076] Note that embodiment 6 encountered a fact that the substrate
body was partially decolored and the insulating layer deteriorated.
Similarly to the foregoing inspection, the substrates made of resin
except for embodiment 6 has the structures that the melting point
of the soldering material is a relatively low temperature of
280.degree. C. or lower. Also the soldering temperatures are
somewhat higher than the melting points by about 10.degree. C. On
the other hand, embodiment 6 is arranged to use the soldering
material having the melting point which is 315.degree. C. and
arranged to perform soldering at 325.degree. C. Thus, the
temperatures are high as described above. When a substrate body
made of a material, such as polyimide, having excellent heat
resistance was employed, decoloration of the substrate body and
deterioration in the insulating layer did not occur when the
soldering material according to embodiment 6 was employed,
similarly to embodiment 3.
[0077] As described above, the substrate 21 made of resin according
to embodiments 4, 5 and 6 has the structure that the soldering
material 35 for securing the pins 31 and the substrate body 22 is
made of Sn--Sb. Therefore, low wettability can be realized as
compared with the Pb--Sn soldering material. Therefore, the height
HS of upward movement can be reduced. It leads to a fact that the
shaft portion 31B of the pin 31 can sufficiently deeply be inserted
into the through hole TDH. Thus, gap TS between the first main
surface 22A of the substrate body 22 and the upper surface WBA of
the other substrate WB can be reduced. Therefore, the overall
height realized after the substrate 21 made of resin has been
connected to the other substrate WB can be reduced.
[0078] The projection height PS of the pin 31 is a short length of
1 mm. However, also the height of upward movement of the soldering
material 15 is reduced. Therefore, the portion of the shaft portion
11B, the diameter of which is enlarged, is decreased. Thus, the pin
can deeply be inserted into the through hole TDH of the other
substrate WB so that reliable connection is established.
[0079] Since the Au-plated layer 33 formed on the surface of the
pin 31 has a large thickness of 0.05 .mu.m, the antioxidation
characteristic and reliability of the connection with the other
substrate WB can be improved.
[0080] Moreover, the melting point of the soldering material 35
according to embodiments 4 and 5 is relatively low. Therefore, a
material having excellent heat resistance is not required to
prevent decoloration of the resin insulating layer 23 and the
solder resist layer 25 and deterioration in the insulating
characteristic when soldering is performed at a high
temperature.
[0081] The substrate 21 made of resin according to this embodiment
is manufactured such that the substrate body 22 is manufactured by
a known method. Then, an annular solder preform made of the Sn--Sb
soldering material 35 (95Sn--5Sb in embodiment 4, 98Sn--2Sb in
embodiment 5 and 80Sn--20Sb in embodiment 6) is placed on the
second connection pad 28 of the first main surface 22A of the
substrate body 22. Then, the pins were inserted, and then the
soldering material 35 is heated at a temperature which is higher
than the melting point by about 10.degree. C. for one minute. Thus,
the pins 31 are secured to the substrate body 22 so that the
substrate 21 made of resin is manufactured.
[0082] The embodiments of the present invention have been
described. The present invention is not limited to the description
of the embodiments. As a matter of course, arbitrary modifications
may be performed within the scope of the spirit of the present
invention.
[0083] For example, embodiments 1, 2 and 3 have the structure that
the substrate 1 made of resin is joined to the socket ST. In
embodiments 4, 5 and 6, the substrate 21 made of resin is joined to
the other substrate WB. The substrate 1 made of resin according to
embodiments 1 and the like may be joined to the other substrate or
the substrate 21 made of resin according to embodiments 4 and the
like may be joined to the socket. The length of each of the shaft
portions 11B and 31B of the pins 11 and 31 may arbitrarily be
adjusted. In any case, the height HS of upward movement of the
soldering materials 15 and 35 can be reduced. Therefore, the gap
between each of the substrate bodies 2 and 22 and the other
substrate or the socket can be reduced.
* * * * *