U.S. patent application number 10/944752 was filed with the patent office on 2005-02-24 for contact pin and socket for electrical parts.
This patent application is currently assigned to Enplas Corporation. Invention is credited to Miura, Akira.
Application Number | 20050042905 10/944752 |
Document ID | / |
Family ID | 26615528 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050042905 |
Kind Code |
A1 |
Miura, Akira |
February 24, 2005 |
Contact pin and socket for electrical parts
Abstract
A contact pin for an IC socket. The contact pin is formed from a
metal material having conductivity and includes an elastic portion
that is elastically deformable by a force applied thereto. A
contact portion is formed at an end portion of the elastic portion
and contacts an IC lead of an IC package. The elastic portion is
polished to improve durability.
Inventors: |
Miura, Akira;
(Kawaguchi-shi, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
SUITE 700
1201 NEW YORK AVENUE, N.W.
WASHINGTON
DC
20005
US
|
Assignee: |
Enplas Corporation
Saitama
JP
|
Family ID: |
26615528 |
Appl. No.: |
10/944752 |
Filed: |
September 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10944752 |
Sep 21, 2004 |
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10151000 |
May 21, 2002 |
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6811420 |
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Current U.S.
Class: |
439/266 |
Current CPC
Class: |
H05K 7/1023 20130101;
H01R 12/89 20130101; H01R 4/26 20130101 |
Class at
Publication: |
439/266 |
International
Class: |
H01R 013/62 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2001 |
JP |
2001-152926 |
May 28, 2001 |
JP |
2001-158525 |
Claims
What is claimed is:
1. A method of manufacturing a contact pin for a socket,
comprising: punching out a contact pin having a predetermined shape
from a thin, conductive metal plate; polishing the contact pin to
provide a predetermined surface roughness; and applying one or more
metal platings to the polished contact pin to improve elastic
strength of the contact pin.
2. The method according to claim 1, wherein the predetermined
surface roughness is achieved by removing an acute angle portion of
a surface of the contact pin.
3. The method according to claim 1, wherein said applying one or
more metal platings to the polished contact pin comprises applying
a nickel plating to increase thickness of the contact pin.
4. The method according to claim 3, wherein said applying one or
more metal platings to the polished contact pin further comprises
applying a gold plating after application of the nickel plating.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 10/151,000, now allowed. This application also claims the
benefit of Japanese Application No. 2001-152926, filed May 22, 2001
and Application No. 2001-158525, filed May 28, 2001, in the
Japanese Patent Office, the disclosures of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a contact pin utilized for
a socket for electrical parts for detachably accommodating and
holding an electrical part such as a semiconductor device (called
as "IC package" hereinlater), and also related to a socket for
electrical parts provided with such contact pin.
[0004] 2. Related Art of the Invention
[0005] In a known art, there has been provided an IC socket, as
"socket for electrical parts" mentioned above, for carrying out
performance test of an IC package as "electrical part", which is
preliminarily disposed on a printed circuit board and in which an
IC package is accommodated in this IC socket to thereby establish
an electrical connection between the IC package and the printed
circuit board.
[0006] As such IC package, there is provided one having, for
example, a rectangular body having a side portion from which a
number of terminals extend sideways.
[0007] Under the state that the IC package is accommodated in the
IC socket, when contact portions of contact pins of the IC socket
contact to a number of terminals of the IC package, respectively,
the terminals and the printed circuit board are electrically
connected through the contact pins.
[0008] Such contact pin is formed by being punched out from a metal
thin plate having conductivity, by means of press working, so as to
have an elastic portion, which is elastically deformed by being
pressed by an operation member which is vertically movable and a
contact portion formed to a front (top) end side of the elastic
portion and adapted to contact the terminal of the IC package.
[0009] When the IC package is accommodated in the IC socket, the
operation member is lowered. The operation member is formed with a
cam portion which presses a contact piece of the contact pin to
thereby elastically deform the elastic portion and retire the
contact portion of the contact pin from an insertion range of the
terminal of the IC package.
[0010] Under the state mentioned above, the IC package is
accommodated in an accommodation portion of an IC socket body, and
thereafter, the operation member is moved upward. According to this
upward movement, the contact portion of the contact pin returns to
its initial position by the elastic force of the elastic portion
thereof, and the contact portion is then contacted to an upper
surface of the terminal of the IC package to thereby establish the
electrical connection therebetween.
[0011] However, in the known structure mentioned above, there may
cause a case that a rough or course cut surface may be provided at
the time of punching out the contact pin from the metal thin plate,
and, in such case, according to the repeated operation of
accommodation or removal of the IC package, the elastic portion of
the contact pin may be loaded repeatedly and a stress is
concentrated on a corner portion thereof by the coarse surface of
the elastic portion, thus facilitating fatigue and making worse its
durability.
SUMMARY OF THE INVENTION
[0012] An object of the present invention is to substantially
eliminate defects or drawbacks encountered in the prior art
mentioned above and to provide a contact pin used for a socket for
electrical parts having an improved structure of an elastic portion
of the contact pin and also provide a socket for electrical parts
having such improved contact pin.
[0013] This and other objects can be achieved according to the
present invention by providing, in one aspect, a contact pin for an
electrical part formed from a metal material having conductivity,
comprising:
[0014] an elastic portion elastically deformable; and
[0015] a contact portion formed to a tip end portion of the elastic
portion and adapted to contact a terminal of an electrical
part,
[0016] wherein the elastic portion is polished by polishing
means.
[0017] According to this aspect, the elastic portion of the contact
pin is formed to have a smooth surface by the polishing means, so
that a load is not concentrated at a specific portion even if the
load is repeatedly applied, and hence, the durability of the
contact pin can be improved.
[0018] In a preferred embodiment of this aspect, the polishing is
performed, such as chemical polishing, without applying any
external force. A nickel plating may be effected to the elastic
portion to which the chemical polishing has been made.
[0019] The elastic portion is formed to provide a curved shape.
[0020] According to the preferred embodiment mentioned above, the
contact pin even being small in size and weak in strength can be
polished, by such as chemical polishing, by applying no external
mechanical force. According to the chemical polishing treatment, a
number of contact pins can be polished at the same time by, for
example, dipping them in a polishing solution, thus improving the
workability for manufacturing the contact pins. The nickel plating
will compensate the reduction in thickness of the contact pin
including the elastic portion through the polishing treatment and,
hence, the elastic strength of the elastic portion will be
maintained.
[0021] In a modified aspect of the present invention in the above
aspect, there is provided a contact pin for a socket for an
electrical part formed from a conductive material, comprising:
[0022] a base portion;
[0023] a stationary piece extending from the base portion and
contacting the electrical part; and
[0024] a movable piece extending from the base portion and
contacting the electrical part,
[0025] wherein the movable piece comprises an elastic portion and a
movable contact portion contacting the electrical part and the
elastic portion is polished.
[0026] In this aspect, the chemical polishing treatment will be
preferably applied. The chemical polishing is effected so that the
movable contact portion has a surface roughness of a value less
than a predetermined value.
[0027] In another aspect, the contact pin of the present invention
is applied to a socket for an electrical part, and the socket for
an electrical part having a terminal comprising:
[0028] a socket body to which an electrical part is mounted;
[0029] an operation member provided for the socket body to be
vertically movable in an operative state, the operation member
being formed with a cam portion;
[0030] a contact pin provided for the socket body, the contact pin
formed from a metal material having a conductivity and comprising
an elastic portion elastically deformable, a contact portion formed
to a tip end portion of the elastic portion and adapted to contact
the terminal of an electrical part, and an operation piece to be
pressed by the cam portion of the operation member,
[0031] wherein the elastic portion is polished by polishing means,
and the elastic portion is elastically deformed when the operation
member is moved downward and the operation piece of the contact pin
is pressed by the cam portion of the operation member to thereby
separate the movable contact portion from the terminal of the
electrical part.
[0032] The socket is an IC socket provided with a number of contact
pins and the electrical part is an IC package provided with a
number of IC leads as the terminals.
[0033] The nature and further characteristic features of the
present invention will be made more dear from the following
descriptions made with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In the accompanying drawings:
[0035] FIG. 1 is a sectional view of an IC socket provided with a
contact pin according to an embodiment of the present invention and
showing a state that a movable piece of the contact pin is
closed;
[0036] FIG. 2 is also a sectional view of the IC socket of FIG. 1
showing a state that the movable piece is opened;
[0037] FIG. 3 is a sectional view, in an enlarged scale, of a
portion the contact pin of FIG. 1 showing a state that an IC lead
is clamped;
[0038] FIG. 4 is an enlarged perspective view of the movable piece
of the contact pin of FIG. 1; and
[0039] FIG. 5 is a view, in an enlarged scale, showing a surface
roughness of the contact pin such as a portion of a movable contact
portion thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0040] A preferred embodiment of the present invention will be
described hereunder with reference to the accompanying drawings of
FIGS. 1 to 5.
[0041] With reference to FIG. 1, an IC socket as "a socket for
electrical parts" is totally designated by reference numeral 11,
and the IC socket 11 is utilized for electrical connection between
an IC lead 12b as "a terminal" for an IC package 12 as "an
electrical part" and a printed circuit board (not shown) of a
tester, in order to carry out a performance test of the IC package
12.
[0042] The IC package 12 is, as shown in FIG. 1, so-called a
gull-wing-type, having a structure in which a number of IC leads
12b project sideways from a rectangular package body 12a of the IC
package 12.
[0043] On the other hand, the IC socket 11 generally has a socket
body 13 to be mounted on a printed circuit board, not shown, and
the socket body 13 is formed with a number of contact pins 15 which
are elastically deformable and connected to be electrically
conductive to the IC leads 12b. The socket body 13 is also provided
with an operation member 16 having a rectangular frame structure to
be vertically movable so as to elastically deform the contact pins
15.
[0044] The socket body 13 is formed with press-in holes 13a into
which the contact pins 15 are pressed and formed, at its upper
surface, with an accommodation portion 13b in which the IC package
12 is mounted and accommodated. Furthermore, guide portions 13c are
also formed to portions of the accommodation portion 13b,
corresponding to corner portions of the IC package body 12a, for
positioning the IC package 12 to a predetermined position.
[0045] Further, it is to be noted that term such as "upper
(upward)", "lower (downward)", and the like are used herein with
reference to the illustration of figures or in a general usable
state of the socket.
[0046] The contact pin 15 has a springy property and is formed from
a metal material having an excellent electrical conductivity. The
contact pin 15 is press-fitted into the press-in hole 13a of the
socket body 13. A number of such contact pins 15 are arranged side
by side.
[0047] More specifically, in the state illustrated in FIG. 1 or 2,
each of the contact pins 15 has a base portion 15a from which a
lead portion 15b extends downward, and the lead portion 15b has a
root to which is formed a claw portion 15c which is press-contacted
to an inner wall section of the press-in hole 13a of the socket
body 13. The lead portion 15b has a part projecting downward from
the socket body 13, which is then electrically connected to the
printed circuit board.
[0048] Furthermore, a stationary contact piece 15d is formed to the
upper portion of the base portion 15a so as to extend upward, and
this stationary contact piece 15d is composed of an elastic portion
15f extending upward from the base portion 15a and a stationary
contact portion 15e formed at the top end side of the elastic
portion 15f so as to contact the lower surface side of the IC lead
12b.
[0049] Still furthermore, outside the stationary contact piece 15d
(left side as viewed in FIG. 1), is disposed a movable contact
piece 15i so as to extend upward. This movable contact piece 15i is
composed of a curved elastic portion 15j, a movable piece 15k
continuous to the curved elastic portion 15j and an arm portion 15m
formed to the movable piece 15k so as to extend inward. The arm
portion 15m has, at its front end portion, a movable contact
portion 15n so as to contact the upper surface of the IC lead 12b.
According to the structure mentioned above, the IC lead 12b of the
IC package 12 is clamped from the upper and lower sides by the
movable contact portion 15n and the stationary contact portion 15e.
Further, the movable piece 15k is provided with an operation piece
15p so as to extend upward.
[0050] On the other hand, as shown in FIG. 1, the operation member
16 has an opening 16a of a size capable of the IC package 12 being
inserted, and the IC package 12 inserted through this opening 16a
is mounted on the accommodation portion 13b of the socket body 13.
The operation member 16 is provided for the socket body 13 to be
vertically movable and is urged upward by means of a spring, not
shown.
[0051] Furthermore, the operation member 16 is formed with a cam
portion 16b, which contacts the operation piece 15p of the contact
pin 15 in a slidable manner. When the operation member 16 is
lowered, the operation piece 15p is pressed by the cam portion 16b
of the operation member 16 and the elastic portion 15j is then
deformed elastically, and as shown in FIG. 2, the movable piece 15k
is deformed in an obliquely outside upward to be opened.
Accordingly, the movable contact portion 15n is moved so as to be
separated from the IC lead 12b. Further, when the operation member
16 is moved upward, an operation reverse to that mentioned above
will be performed. That is, the movable contact portion 15n is
deformed obliquely downward by the elastic urging force of the
elastic portion 15j and the IC lead 12b is clamped between the
movable contact portion 15n and the stationary contact portion 15e
to thereby establish an electrical connection therebetween. At this
clamping operation, the movable contact portion 15n is slightly
slid on the IC lead 12b.
[0052] In an actual arrangement, a number of contact pins 15, each
having the structure mentioned above, are arranged. Each of the
contact pins 15 is formed in the following manner.
[0053] That is, a thin metal plate of, for example, copper alloy,
having an excellent conductivity is punched out to provide a
predetermined shape through a press working. The thus punched out
piece is chemically treated to be polished by polishing means so as
to provide cut portions including the movable contact portion 15m
and the elastic portion 15j having surface roughness L of a value
less than that at the time of punching press working, for example,
not more than 1 .mu.m (see FIG. 5).
[0054] The contact pin 15 of the structure mentioned above will be
manufactured or formed by the following method or process.
[0055] At first, a thin metal plate, as a metal material, of copper
alloy is punched out, through the press working, into a
predetermined shape and then is subjected to a chemical
polishing.
[0056] The chemical polishing is performed by dipping the metal
material into a mixed solution of a strong acid solution and a
solution having a strong oxidation force to thereby provide gloss
and smoothness to the surface of the metal material.
[0057] In the present invention, the punched-out copper alloy thin
plate is dipped into a mixed solution consisting of sulfuric acid
solution (100-200 g/l), hydrogen peroxide solution (30-70 g/l), as
main component, and a saturated alcohol solution (small amount) at
a solution temperature of 20-40.degree. C. for 20 to 120 sec.
[0058] In other wards, in this chemical polishing treatment, it is
necessary to set a condition of treatment to such that the surface
roughness L of the surface of the movable contact portion 15n of
the contact pin 15 is less than that at the punched-out process by
the press working (for example, not more than 1 .mu.m).
[0059] Thereafter, nickel plating, and then gold plating, are
effected to the portion to which the chemical polishing was
effected.
[0060] Further, such chemical polishing, by which any mechanical
external force is not applied to the contact pin 15, makes it
possible to polish even a small contact pin having a weak
mechanical strength without deforming the same.
[0061] Furthermore, according to such chemical polishing treatment,
a number of contact pins 15 can be dipped and polished at the same
time, improving the workability in comparison with a mechanical
polishing work by which the contact pins are to be polished one by
one.
[0062] Still furthermore, when the contact pin 15 is polished, the
thickness of the contact pin 15 including the elastic portion 15j
is reduced. However, in the present invention, this thickness
reduction is compensated by effecting the nickel plating to thereby
ensure the elastic strength of the elastic portion 15j of the
contact pin 15 and hence ensure the proper contacting pressure
between the movable contact portion 15n and the IC lead 12b.
[0063] The IC socket 11 of the characters mentioned above will be
used in the following manner.
[0064] At first, the lead portion 15b of the contact pin 15 of the
IC socket 11 is preliminarily inserted into the insertion hole of
the printed circuit board and then soldered, and in this condition,
a plurality of such IC sockets 11 are arranged on the printed
circuit board. Then, the IC package 12 is set by, for example, an
automatic machine to thereby establish an electrically connection
therebetween.
[0065] That is, the operation member 16 is depressed and lowered,
with the IC package 12 being held, by the automatic machine against
the urging force of both of the spring, not shown, and the contact
pin 15. Then, as shown in FIG. 2, the operation piece 15p is
pressed by the cam portion 16 of the operation member 16, the
elastic portion 15j is then elastically deformed, the movable piece
15k is deformed obliquely upward and opened maximally, and the
movable contact portion 15n is retired from the IC package
insertion range.
[0066] Under this condition, the IC package 12 is released from the
automatic machine and is mounted on the accommodation portion 13b
of the socket body 13.
[0067] In this mounting operation, the IC package 12 is guided and
positioned to the predetermined position by the guide portions 13c,
and the IC lead 12b of the IC package 12 is surely placed on the
upper surface 15q, as the contacting surface, of the stationary
contact portion 15e of the contact pin 15.
[0068] Thereafter, when the pressing force of the operation member
16 applied by the automatic machine is released, the operation
member 16 is moved upward by the elastic force of the contact pin
15 and the urging force of the spring and the movable piece 15k of
the contact pin 15 begins to return to its initial position. At a
time when the operation member 16 has been moved upward to the
predetermined position, the movable contact portion 15n of the
contact pin 15 abuts against the upper surface of the predetermined
IC lead 12b of the IC package 12 positioned in the manner mentioned
above and, thereafter, wiped by a predetermined amount, whereby
this IC lead 12b is clamped between the movable contact portion 15n
and the stationary contact portion 15e to thereby establish the
electrical connection therebetween as shown in FIG. 3.
[0069] As mentioned above, at a time of mounting or dismounting the
IC package 12, the elastic portion 15j of the movable contact piece
15i of the contact pin 15 is elastically deformed repeatedly
through the vertical movement of the operation member 16. According
to this invention, however, the elastic portion 15j is chemically
polished as mentioned above to provide a smooth flat surface
thereof, so that, when a load is applied repeatedly to the elastic
portion, the load is not concentrated to any specific portion, and
thus, the durability in use thereof can be improved.
[0070] Further, it is to be noted that the present invention is not
limited to the described embodiment and many other changes and
modifications may be made without departing from the scopes of the
appended claims.
[0071] For example, although, in the described embodiment, the
present invention is applied to an IC socket as a socket for
electrical parts, the present invention will be applied to other
devices or like.
[0072] Moreover, although, in the described embodiment, the
chemical polishing is utilized as polishing means, other polishing
method or treatment such as electrolytic polishing, sand blasting,
or shot peening may be utilized. Still furthermore, although, in
the described embodiment, the contact pin 15 is entirely polished,
only the elastic portion 15j thereof may be polished, and a
polishing amount thereof may be less than that of the movable
contact portion 15n so as to provide an R-shape, as shown in FIG.
5, with an acute angle portion of the surface of the punched
material being removed.
[0073] Still furthermore, in the present embodiment, although the
contact pin 15 is so-called a two-point type contact pin provided
with the stationary contact piece 15d, one-contact type contact pin
having only the movable contact piece may be equivalently
utilized.
* * * * *