Socket

A socket for use in the burn-in test, which is characterized in that a contact element and a fixed member are displaced from their original positions in connection with the forward motion of the cover member for charging an IC package into the main socket body. Upon the return of the fixed member and the contact element to their respective initial positions, the leads of the IC package are held between them, thereby carrying out the reliable fixing of the IC package. Additionally, the fixed member is integrally constructed with a compressive part of molded resin and a metal part that supports the compressive part.

BACKGROUND OF THE INVENTION 
This invention relates to a socket having a contact element which is to be 
elastically compressed to an electrical part so as to establish electric 
contact in connection with the installation of a semiconductor integrated 
circuit chip (IC) by inserting a molded IC package such as for example, a 
socket for IC chip use. 
As the IC package has become thinner and smaller in size in recent years, 
and as applications for surface installations have increased, the quality 
of the product has become more difficult to control. This situation makes 
for testing and the elimination of unacceptable products very important. 
With this fact in mind, standard testing (such as a heat resistant test 
that is called a burn-in test) of IC packages including IC packages for 
surface installation is performed in which IC packages are placed in a 
testing furnace so as to distinguish the good from the bad products. 
One type of socket as known in the prior art used for such testing is the 
so-called ZIP (zig-zag in-line package) socket 10 which is shown in FIGS. 
9 through 11. An IC package 2 which is installed on this ZIP socket is 
designed so that the loads 5a and 5b extending from the bottom of the 
molded resin portion of the IC 2a are in two rows for insertion into the 
socket 10 as clearly shown in FIG. 9. The contact element 4 of the socket 
is formed as a single metal piece which is bent back at its lower end with 
the bent part being inserted into the base of the socket. 
For installation of the IC package, the IC package 2 is faced in the 
perpendicular direction and the leads are inserted into the respective 
lead insertion holes 3 corresponding to the various leads. Each lead is 
inserted between the mutually facing elastic holding parts 4a and 4b of 
the pin-shaped contact element 4 that has been positioned in the lead 
insertion hole 3 so as to elastically hold the lead as shown in the 
drawings. An action opposite to that described above is carried out in 
order to withdraw the IC package 2 from the socket. 
It has been found, however, that the aforementioned ZIP socket has certain 
shortcomings. In an automated operation for insertion and withdrawal from 
the socket, the IC package may be positioned sideways on the tray because 
of its shape which requires that the packages have to be repositioned in 
the perpendicular (vertical) direction before they are inserted into the 
socket with the consequence that the steps required for automation become 
more complicated. Additionally, the leads 5a and 5b of the IC are pushed 
into the gap between the mutually facing holding parts 4a and 4b thereby 
separating these holding parts and giving rise to the possibility of the 
leads and contacts being deformed. 
BRIEF SUMMARY OF THE INVENTION 
In accordance with the present invention, an electrical parts (IC) are 
charged into the main socket body by displacing a contact element and a 
fixed member in connection with the forward motion of the reciprocating 
motion member, and thus the fixing of said electrical parts and 
specifically the terminal part upon the return motion of the reciprocating 
member. The leads, therefore, of the electrical part are not pressed or 
inserted into the contact point but held in position between the contact 
element and the fixed member upon return of the contact member and 
specifically the contact point to its original position. This design 
allows for the contacting of all the connective terminal parts of the 
electrical parts under the same contact pressure and best provides for 
sufficient contact pressure. 
It is an object of this invention to provide a socket with uniform and 
satisfactory contact pressure which can be reduced in size so as to easily 
mount and dismount an electrical part such as an IC chip by an automatic 
tool, which is capable of being used in common for various lead lengths 
and shapes, and in which the external size of the socket can be reduced 
for improved installation density. 
Briefly described, the socket of this invention comprises a socket having a 
contact element which is electrically connected in a compressed state to 
the connective terminal part of a prescribed electrical part that is to be 
installed in a socket, a fixed member that holds the connective terminal 
part of the electrical part between it and the contact element and a 
reciprocating motion member mounted on the main socket body in such a 
manner as to be adapted for reciprocating motion with the contact element 
and the fixed member to displace them from their original positions in 
connection with the forward motion of the reciprocating motion member, 
thereby providing for insertion of the electrical part into the main 
socket body, and upon the return of the fixed member and the contact 
element to their original position, the connective part of the electrical 
part is held between the fixed member and the contact element so as to 
carry out the electrical connection of the connective terminal part to the 
contact element. Preferably the fixed member is formed integrally with a 
resin molded part or the like that is in direct contact with the 
connective terminal part and a metal part that supports the resin molded 
part. It is further understood that in accordance with this invention that 
the reciprocating motion can be carried out simultaneously with the fixing 
of the electrical part or as an alternative in the wake of the fixing of 
the electrical part.

FIGS. 1-7 show the ZIP socket 50 for use in testing an IC. A contact 
element 24 is formed of an electroconductive material. It comprises a 
fixed terminal part 24c mounted in a base 21 of the main socket body, a 
lead part 24d which protrudes downward from the fixed terminal part 24d, 
an elastic bent part 23 generally in the form of an arc which is joined to 
the fixed terminal part 24c, a sliding contact part 20 which is linked to 
the bent end of the bent part 23 and contact points 24a and 24b. 
These contact points 24a and 24b are arranged to have different heights so 
as to conform with the leads 5a and 5b of the IC to be provided at the top 
of an erect part 55 that runs upward through each of the through holes 
that are formed in a cover member 30 that will be described later. 
A fixed latch member 40 which sandwiches and holds the leads 5al and 5b of 
the IC package 2 with the molding and IC chip against the contact points 
of the contact element 24 comprises a lever part 41 (see FIG. 7) which 
stands erect in the form of an "U" from the fulcrum pin 43 which is fixed 
to the main socket body 21, a linking part 44 which is linked in the right 
angle direction as compared with this lever part 41, and a protruding part 
42 which protrudes upward from this linkage part 44. 
Lever part 41 and link part 44 are typically made from a metal such as 
stainless steel, etc., and the lead compression part 51 which has been 
provided at the top of the lever part 41 is made from a molded resin such 
as epoxy resin, etc., (see FIG. 4). The lead compression part 51 has a 
compressive surface where the concave part 51a and the convex part 51b 
corresponding to the various leads 5a and 5b of the IC are arranged 
alternately. The compressive surface of the concave part 51a and convex 
part 51b are generally spherical. 
A coil spring 45 is combined in a cavity 52 formed in the main socket body 
21 with the top of the spring 45 in contact with the linkage part 44 of 
the fixed member 40 thereby giving impetus in the counter clockwise 
direction (see FIG. 1). Additionally, linkage part 44 of fixed member 40 
is arranged inside a groove 27 that has been provided on the base 1. 
The reciprocating cover member has a hole 34 for the insertion of sliding 
part 20 of contact 24 with an inclined surface 32 being provided in hole 
34 upon which part 20 slides. A surface 60 for receiving the IC package 2 
is provided on the main socket body 21 so that the IC package 2 may not be 
lowered beyond a certain fixed height. 
At the lower end of the cover member 30, there is fixed a shaft 53 as a 
compressive member that is in contact with protruding part 42 of linkage 
part 44 that has been described earlier and that drives same (see FIGS. 
1-3). 
Even though the cover member 30 is capable of engaging in reciprocating 
motion up and down, as compared with the base 21, it is given an upward 
impetus at all times by a spring 54 that has been provided on the base 21. 
It is mentioned in this connection that item 56 in FIG. 5 indicates a 
stopper for stopping the cover member 30 from escaping upward. 
In the paragraph below the action for the inserting of the IC package 2 in 
the main socket body will be explained. 
As shown in FIG. 2, the cover 30 that has been installed at a prescribed 
location on the main socket body 21 moved lower in the direction indicated 
by an arrow 38 from the position in the normal state shown in FIG. 1 by 
means of an external force. 
At this time, the sliding part 20 of the contact element 24 moves in the 
clockwise direction, while sliding on the inclined surface 32. At the same 
time, the contact points 24a and 24b move in the same direction to 
separate from lead 5. A force is required to some extent at this time for 
the elastic deformation of the contact in connection with this movement; 
however, that force does not have to be big in view of the shape which has 
been described above. 
When the cover 30 is moved downward, a shaft 53 which is located a the 
bottom of the cover member 30 contacts the protruding part 42 of the fixed 
member 40. If the cover member 30 is further moved downward in the 
direction indicated by arrow 38, the protruding part 42 is pushed down by 
the cover member 30, with the result that the lever 41 of fixed member 40 
rotating in the clockwise direction in opposition to the spring force of 
spring 45 thereby allowing IC package 2 to be inserted or withdrawn. By 
further pushing down the cover member 30 until it contacts the main socket 
body 21, the fixed member 40 (lever 41) is brought into a fully open state 
as shown in FIG. 3. 
In the state of the fixed member (lever 41) being wide open as described 
above, the IC package 2 is inserted into the cover member 30 and the IC 
package 2 is charged to a prescribed position in the main socket body. 
Then by releasing the force that pushes down the cover member 30 
thereafter, the fixed member 40 and the contact element 24 and further the 
cover member 30 move in a direction which is opposite to the 
above-described movement to be restored to the original position. 
In other words, upon releasing the external force, the restoring force of 
the spring 45 which is in the compressed state causes the fixed lever 41 
to rotate in the counter clock-wise direction to restore the socket to the 
original position. Moreover, the sliding part 20 of the contact element 24 
slides along the wall surface of the through hole 34 so that the cover 30 
is pushed to the original position by the elastic restoring force of the 
spring 54. Also, contact element 24 tries to return to the original shape 
shown in FIG. 1 as sliding part 20 moves from the bottom of the through 
hole 34. 
As a result of the above-described return movement, the contact element 24 
is returned back to the original position as is fixed member 40 and the 
contact points 24a and 24b come into contact from below with the leads 5a 
and 5b that are located under the fixed member 40 and, as is shown in FIG. 
1, the leads 5a and 5b are brought into the state where they are held 
between the compressive surfaces 51a and 51b of fixed member 40 and the 
contact points 24a and 24b respectively. 
FIGS. 1-3 show the state where the IC package 2 has already been installed. 
The above explanation generally describes the method for inserting the IC 
package in a non-installed state into a socket (additionally see FIGS. 
5-7). For removal of the IC package 2, the procedure as described above 
would be done in reverse. 
It can be seen from what has been explained above that the socket according 
to this invention has the following advantages: 
(1) The socket is so constructed that the contact element 24 and fixed 
member 40 are displaced from the original position upon the downward 
movement of the cover member 30 by an external force thereby providing for 
the insertion of an IC package 2 into the main body 21. When the fixed 
member 40 and the contact element 24 are returned to their original 
positions respectively, the IC package 2 is contained in the main socket 
body 21 with a hold on leads 5a and 5b. 
Accordingly, it is not that leads 5a and 5b are pushed into contact with 
the contact points 24a and 24b or that the leads are inserted between the 
contact points but that, subsequent to the fixing of the IC package 2, the 
contact points 24a and 24b are restored by their own strength contacting 
the leads 5a and 5b from underneath and thereby pushing up the leads by 
the spring force of the contact element 24 itself, while the top of the 
lead is compressed or held by the compressive part 51 of the fixed member 
40 so that the leads will not rise unnecessarily. 
Since the various leads are elastically held between the fixed member 40 
and the contact element 24, the contact pressure by the contact element 24 
is controlled and sufficient. Moreover, since contact is established under 
the same contact pressure for both of the leads 5a and 5b which are 
arranged in a zig zag fashion, there is minimal variation in the contact 
pressure between the leads with a sufficient contact pressure being 
obtained. Thus, there will be no bending or non-alignment of the leads and 
also the contact element 24 does not produce any deformation such as a 
bending, etc. 
(2) The socket has a construction to hold the leads 5a and 5b from above 
and below. This construction allows for accurately holding of the leads 
even if the lead length may change or vary because the leads merely extend 
out from the holding position. That is, irrespective of the length of the 
lead or shape thereof, the design provides for accurately holding the 
leads under a prescribed contact pressure so that one kind of socket can 
be used in common for different kinds of IC packages. 
(3) In connection with insertion of the IC package 2, it is possible to do 
same without the addition of any force to the IC package so long as the 
socket is in the state as shown in FIG. 3. This feature is important to 
ensure that contact element deformation does not take place. This feature 
is especially noteworthy and beneficial for IC's where the leads are 
arranged in a zig-zag fashion. 
In addition it becomes possible to remove the IC package 2 in its 
horizontal state by such means as vacuum suction, etc., and insert same 
into the socket, thereby making it possible to reduce assembly and 
disassembly time. 
(4) The socket of the present invention has good dimensional accuracy and 
mechanical strength along with good electrical insulation properties by 
providing for fixed member 40 to hold the leads which is formed integrally 
with a compressive portion 51 made of molded resin and a lever portion 41 
made of metal which are joined together. That is, it would be ideal to 
form the fixed member from a material of high strength so that the socket 
can be made of minimal size. However, such a fixed member needs to exhibit 
dimensional accuracy and provide the needed insulation. Accordingly, the 
lever part 41 is made out of metal thereby adhering the reduction in size 
with the part that directly presses against the leads being made from an 
electrically insulating material formed by forming it to the metal 
portion. 
As compared with the fixed member being made entirely from molded resin, it 
becomes possible to reduce the dimensions of the fixed member and thus the 
socket itself. It is then possible to improve the installation density of 
the sockets on the board for testing and, at the same time, it becomes 
possible to realize both insulation and dimensional accuracy required. 
Accordingly, the joining of the lever part 41 and the compressive part 51 
can be carried out as follows: First, the lever part 41 is prepared by 
using a metal of desired size to which compressive portion 51 is molded as 
by the insert molding process. Alternatively, a hole for insertion can be 
provided on the molded compressive part 51 with the lever part 41 
compressively joined thereto. 
(5) To further provide reduced size of the socket, both sliding part 20 and 
the contact points 24a and 24b have been provided on an erect part 55 that 
extends upward up from the bent part 23 of the contact element 24 so that 
the size is reduced in the horizontal direction of the contact element 24 
as a whole and, thus the size of the socket becomes smaller. 
(6) The IC package 2 can be inserted into the main socket body 21 by means 
of a simple action involving the reciprocating motion of the cover member 
30. Accordingly, there is no need for carrying out complicated steps. This 
feature is highly advantageous from the standpoint of promoting 
automation. Even using an automatic tool, etc., the IC package 2 can be 
fixed on the main socket body 21. 
An alternate embodiment of this invention will now be explained in 
reference to FIG. 8. In this embodiment there is provided a socket for the 
SOP (small outline package) in which the leads 5 of the IC package 2 have 
the same shape and are taken out in one direction and that the package 2 
can be positioned by means of a protruding part 7 that is provided on main 
body 21. The other construction remains the same as the above-described 
socket. It is pointed out, however, that the compressive surface of 
compressive part 51 of fixed member 40 has a straight shape. 
Additionally, the socket of this embodiment is functional for packages 
having different lead lengths, provided that the dimensions of the mold 
part 2a of the IC package 2 are equal as is set forth above. In the case 
where the dimensions of the mold part 2a are different, the common use of 
the socket becomes possible only if the IC package is accommodated in an 
adapter and said adapter is charged into the socket. 
In the construction of this embodiment as with that described earlier, the 
leads are held from above and below making it possible to charge the IC 
package without producing any deformation of the lead and contact element 
while assuring proper contact pressure. 
Thus, in accordance with the present invention, the electrical parts (IC) 
are charged into the main socket body by displacing the contact element 
and the fixed member in connection with the forward motion of the 
reciprocating motion member, with the fixing of said electrical parts and 
specifically the terminal part upon the return motion of the reciprocating 
member. The leads, therefore, of the electrical part are not pressed or 
inserted into the contact point but held in position between the contact 
element and the fixed member upon return of the contact member and 
specifically the contact point to its original position. This design 
allows for the contacting of all the connective terminal parts of the 
electrical parts under the same contact pressure and best provides for 
sufficient contact pressure. 
Moreover, operation for the fixing of the electrical parts can be carried 
out easily by a simple reciprocating motion without requiring a 
complicated action, with a consequence that it is easy to effect 
automation by using an automatic machine. Since the reciprocating motion 
construction is based on the reciprocating motion member, further, it 
becomes possible to reduce the size of the socket itself. 
Still further, since the connective terminal part is held in this 
structure, said holding can be carried out accurately at a prescribed 
location at all times even when the length of the lead or terminal part 
may vary or when the lengths are different. Irrespective of the length 
(and the shape) of the connective terminal part, the holding of the part 
can be carried out accurately at all times and one kind of sockets can be 
used commonly for a plurality of electrical parts. 
Lastly, in accordance with this invention, the fixed member for holding of 
the leads is made with two integral portions with the compressive part of 
the molded resin and the resilient part of metal. This provides for good 
mechanical strength along with satisfactory electrical insulation and 
sufficient dimensional accuracy, thereby making it possible to reduce the 
dimensions of the fixed member and thus the outer dimensions of the socket 
itself. This then results in improved socket installation density on the 
board for testing and, at the same time, both good insulation and 
dimensional accuracy. 
The invention has been illustrated above by the description of specific 
examples. It should be added that further modifications can be made still 
within the scope of this invention. For example, the shape, material and 
the installation location, etc., of the contact element and fixed member 
can be modified. In addition, the shape, material and structure of the 
cover member (reciprocating motion member) may also be changed. With 
regard to the structure and material of the fixed member, various methods 
for the integration of the lever part and the mold part can be adapted as 
materials can be suitably selected taking into consideration durability, 
insulation properties, workability, etc. In addition, the material shapes 
and structures of the main body can be suitably selected. 
By way of example in this invention, the IC chips were inserted and fixed 
in the main socket body by reciprocating the cover member in the vertical 
direction. However, it does not have to be always in the vertical 
direction. For instance, the same purpose can be achieved by reciprocating 
it suitably in the horizontal direction. 
There may be a time lag between the fixing of the IC chip and the return of 
the cover member to the original position or they may be carried out 
simultaneously. In addition, the shape, installation method and the kind 
of spring that is provided between the fixed member and the main socket 
body may also be modified. 
This invention can be used in the QFP (quad flat package) and two-member 
forms, etc, in addition to the IC package of the aforementioned type (with 
the load exposed to one member side). In the case of a two member shape, 
it is only necessary to install the fixed member shown in FIG. 7 on the 
side of two opposing members in the same manner, with the cover member 
being used in common. It goes without saying that this invention can be 
used for the electrical parts other than the aforementioned IC chips.