JPH08185946A - Surface mounting ic socket - Google Patents

Abstract

PURPOSE: To make the pressurizing contact between a horizontal U-shaped bent contact and an IC lead proper, and minimize the bulk of a socket by bringing a bent support part formed on the base part of an upper contact piece adjacent to a horizontal U-shaped bent part into contact with a lower contact piece to form a downward displacement supporting point. CONSTITUTION: When a lead contact piece 12 is pushed down, the upper contact piece 9 of a horizontal U-shaped bent contact 3 is displaced downward with a bent supporting part 15 as a displacement supporting point P. The stress load at the downward displacement is born by the bent supporting point 15 and the base part inner surface 17 of a lower contact piece 10 with which the bent supporting point part 15 is brought into contact to displace them downward against the elasticity of the upper contact piece 9. Since the spring constant of the upper contact piece 9 in this downward displacement is inverse proportional to the spring length between the free ends of the lead contact piece 12 of the upper contact piece 9, and the displacement supporting point P or the spring length of the bent supporting part 15 can be shortened adjacent to the free end of the lead contact piece 12, the spring constant of the upper contact piece 9 can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mounting IC socket for surface mounting an IC package on a wiring board.

[0002]

2. Description of the Related Art In a surface mounting IC socket disclosed in Japanese Patent Laid-Open No. 5-3064 as a prior art example, a horizontal U-shaped bent portion 30 is formed by bending a strip horizontally as shown in FIG. 6 (A).
A contact 30 having an upper contact piece 30b and a lower contact piece 30c, which are vertically and substantially parallel to each other and are brought out in parallel with each other in a direction, is planted in parallel along a side edge of the socket body 31. The IC package 32 is mounted on the socket body 31, and the IC lead 3 is attached to the upper contact piece 30b of the contact 30.
3 is placed on the upper contact piece 30 by pushing down the presser cover 34 with the lateral U-shaped bent portion 30a of the contact 30 as a fulcrum.
It is configured such that b is displaced downward and pressure reaction with the IC lead 33 is achieved by its reaction force, and the lower contact piece 30c is soldered to the conductive pattern on the surface of the wiring board 35.

In the above IC socket, the lower surface of the body of the IC package 32 is the IC mounting portion 36 of the socket body 31.
When the upper side of the horizontal U-shaped bent portion 30a of the horizontal U-shaped bent contact 30 contacts the lower surface of the main body of the IC package 32, the downward displacement of the upper contact piece 30b is completed and the IC lead 33 is pressed. The horizontal U-shaped bent portion 30a of the horizontal U-shaped bent contact 30, that is, the height of the IC mounting portion 36 of the socket body 31 and the height of the IC socket are determined by the curvature of the bent U-shaped bent portion 30a. Decided.

[0004]

In the industry, since the mounting height of electronic elements such as resistors and capacitors on a wiring board is about 2 mm, the mounting height of an IC socket for mounting an IC package is reduced. It is required to approach the current size of about 4 mm to about 2 mm as much as possible.

However, as shown in FIGS. 6 (B) and 6 (C), in the contact of the above-mentioned prior art, the bending diameter is made small in order to prevent the lateral U-shaped bending portion 30a from being settled due to repeated bending loads. Has a limit, and the height H2 of the horizontal U-shaped bent portion 30a is large, the bulk of the socket body is also bulky, and its height is about 4 to 5 mm.
In the end, it is not possible to meet the above-mentioned demand for reducing the thickness to about 2 mm. Moreover, in reality, this horizontal U-shaped bent portion 30a
Occupies approximately three-fourths of the contact height H1, and the displacement amount H3 of the upper contact piece 30b can be only about one-fourth, and pressure contact with the lead is also unreliable. Horizontal U-shaped bent portion 30
There is a large variation in the contact level of the upper contact piece 30b due to the error in the curvature of a, and the contact pressure with the IC leads is also uneven between leads.

Further, in order to cope with IC leads which are becoming finer and finer in recent years, it is necessary to further narrow the plate width of the contact, and in the conventional contact in which the lateral U-shaped bent portion serves as the displacement fulcrum of the upper contact piece, the lateral U Severe stress due to repeated displacement concentrates on the bent portion of the character and accumulates to cause fatigue in the bent portion, which not only changes the contact level with the IC lead but also permanently deforms the contact.

As a solution to these problems, it has been considered to dispose the bent portion in the outer region of the socket, but it is difficult to put it into practice because the area occupied by the IC socket with respect to the printed circuit board becomes large.

The present invention solves the problems of the above-mentioned prior art, and can perform pressure contact with the IC lead with high reliability, and the mounting height can be set to about 2 mm.
A socket is provided to meet the above request.

[0009]

[Means for Solving the Problems] As a means thereof, the base portion of the upper contact piece of the contact formed by bending the strip into a substantially horizontal U shape is bent downward to form a bending support portion. An IC in which the lower surface of the top of the bending support portion is brought into contact with the inner surface of the base portion of the lower contact piece so that the bending support portion forms a displacement fulcrum at the time of downward displacement against the elasticity of the upper contact piece. Providing a socket.

A gap is formed between the lower surface of the top portion of the bending support portion and the inner surface of the base portion of the lower contact piece, and the horizontal U-shaped bent portion serves as a first displacement fulcrum when the upper contact piece is displaced downward in the preceding stage. While being formed, the lower surface of the top portion of the bending support portion is brought into contact with the inner surface of the lower contact piece by the downward displacement of the front stage, and after the contact, the bending support portion is displaced downward at the rear stage of the upper contact piece. Provided is an IC socket configured to form a displacement fulcrum.

[0011]

According to the present invention, the bending support portion formed on the base portion of the upper contact piece adjacent to the horizontal U-shaped bent portion is brought into contact with the lower contact piece to form the downward displacement fulcrum. By shortening the spring length and increasing the spring constant of the upper contact piece, a large contact pressure can be obtained even if the contact is minute.

Further, since the level of the lead mounting piece of the upper contact piece can be set on the basis of the contact position of the lower contact piece of the bending support part, the level variation of the lead mounting piece can be eliminated as much as possible. The contact pressure with the lead can be made uniform.

Further, the downward displacement fulcrum of the upper contact piece, particularly the displacement fulcrum when the spring pressure increases toward the latter stage, is not applied to the horizontal U-shaped bent portion as in the conventional case, but is provided on the bending support portion adjacent thereto. By shifting, it is possible to solve the problem of stress accumulated and accumulated in the horizontal U-shaped bent portion due to repeated displacement of the upper contact piece, and prevent the lateral U-shaped bent portion from being settled.

Further, as described above, since the horizontal U-shaped bent portion is not used as a downward displacement fulcrum at least in the subsequent displacement stroke where the elasticity is maximized, the elasticity of the upper contact piece is not influenced by the curvature of the horizontal U-shaped bent portion. Therefore, the curvature of the horizontal U-shaped bent portion can be increased and the height of the bent portion can be reduced, and thus a contact can be formed in which a large amount of displacement of the upper contact piece can be formed, and at the same time, the horizontal U-shaped bent contact can be implanted. Can be made smaller (thinner), and as a result, the overall I
The mounting height of the C socket can be made small.

[0015]

Embodiments of the present invention will be described in detail below with reference to FIGS.

In FIG. 1, 1 is an IC socket main body, 2
Indicates an IC pressing cover, 3 indicates a contact, and 4 indicates an IC package.

The socket body 1 has an IC package 4 at the center.
2. A mounting table 5 for supporting the lower surface of the main body 4a is formed, and as shown in FIG. 2, contact implantation grooves 6 opening at the side edge of the socket main body 1 are arranged in parallel on both sides of the mounting table 5 at equal intervals. The partition wall 7a is formed by raising the outer end of the partition wall 7 between the contact planting grooves 6, 6 adjacent to each other, and the IC lead insertion groove 8 is defined by the adjacent partition walls 7a, 7a. It is continuous with the contact implantation groove 6.

Further, a claw 7'for stopping the engagement of the IC pressing cover 2 with the socket body 1 is provided at the rising end of the partition wall 7a, and the IC pressing cover 2 for pressing the IC package 4 mounted on the socket body 1 is pushed down. The state, that is, the pressure contact state between the lead 4b of the IC package 4 and the contact 3 is secured.

As shown in FIGS. 3 to 5, the contact 3 is an upper bent strip formed by bending an elongated strip punched and formed from a metal plate material having high elasticity such as beryllium copper (BeCu) into a horizontal U shape. The upper contact piece 9 is formed, the lower contact strip 10 is formed by the lower bent strip, and the lateral U-shaped bent portion 11 is formed.
The upper contact piece 9 and the lower contact piece 10 extend in the lateral direction and face each other vertically.

The horizontal U-shaped bent portion 11 is bent in the horizontal U-shape so that the inner diameter R thereof is equal to or less than the plate pressure t of the upper and lower contact pieces 9 and 10, and the height H2 is formed to be small. A lead mounting piece 12 for mounting the lead 4b of the IC package 4 on the free end of 9 is continuously provided so as to face the IC lead 4b, while the free end of the lower contact piece 10 is soldered to the conductive pattern of the wiring board 13. The surface mounting contact pieces 14 to be formed are continuously provided.

Further, the base portion of the upper contact piece 9 is bent downward in a substantially inverted V shape to form a bending support portion 15, and the top lower surface 16 of the bending support portion 15 is formed as shown in FIGS. 3 and 4. The lower contact piece 10 is brought into contact with the inner surface 17 of the base portion.
Free end side of the upper contact piece 9 (lead mounting contact piece 12 side) and side U
The bent portion 11 side is inclined upward from the bending support portion 15 with each other, and the bending support portions 15 are formed in the valley portions of both inclined sides. The top surface 16 of the bending support portion 15 is formed on the lower contact piece. The IC lead 4 is supported by being abutted against the inner surface 17 of the base.
The bending support portion 15 is formed so as to become the displacement fulcrum P at the time of downward displacement against the elasticity of the upper contact piece 9 in the pressure contact with b.

In other words, the upper contact piece 9 is inclined upward with respect to the inner surface of the lower contact piece 10 with which the bending support portion 15 abuts, and the upper side surface of the horizontal U-shaped bent portion 11 and the lead of the upper contact piece 9. A height H3 is formed between the tip of the mounting piece 12 and the upper contact piece 9 to allow the downward displacement. This upper contact piece 9
The downward displacement allowance H3 of is the height H2 of the horizontal U-shaped bent portion 11
Can be made approximately equal to, that is, about ½ of the height H1 of the contact 3. Since the lateral U-shaped bent portion 11 has a structure that does not participate as a fulcrum, the curvature can be made small in diameter and small in volume, which exceeds the limit of plastic deformation.

As a result, when the lead mounting piece 12 is pushed down as shown in FIG. 4, the upper contact piece 9 of the lateral U-shaped bending contact 3 is displaced downward with the bending supporting portion 15 as the displacement fulcrum P, and the bending supporting portion 15 is also moved. And a lower contact piece 1 for abutting this
The base inner surface 17 of 0 bears the stress load at the time of downward displacement, and the downward displacement against the elasticity of the upper contact piece 9 is performed.

The spring constant of the upper contact piece 9 in this downward displacement is inversely proportional to the spring length between the displacement fulcrum P and the free end of the lead mounting piece 12 of the upper contact piece 9, and the displacement fulcrum P, that is, the bending support portion 15, is Since the spring length can be shortened by approaching the free end of the lead mounting piece 12, the spring constant of the upper contact piece 9 can be increased. That is, when the strip width of the contact 3 is made narrow so as to correspond to the fine pitch of the IC leads, a sufficiently large contact pressure can be secured by forming the bending support portion 15 as a fulcrum.

As another example, as shown in FIG.
The bending support portion 15 of the U-shaped bending contact 3 is formed such that the top lower surface 16 thereof and the base inner surface 17 of the lower contact piece 10 have a gap 18 equal to or less than the plate pressure of the lateral U-shaped bending contact 3. Therefore, when the IC lead 4b is pushed down, the elastic force against the elasticity of the upper contact piece 9 is weak, and the first displacement fulcrum P1 is formed by the lateral U-shaped bent portion 11 when the former displacement is made. As shown in FIG. 3B, the top lower surface 16 of the bending support portion 15 is brought into contact with the inner surface 17 of the base of the lower contact piece 10, and after that contact, the bending support portion 15 is attached to the bending support portion 15 as shown in FIG. Forming a second displacement fulcrum P2 at the time of the downward displacement in the subsequent stage where the elasticity of the upper contact piece 9 sharply increases.

That is, by pushing down the lead mounting piece 12, the horizontal U-shaped bent portion 11 is used as the first displacement fulcrum P1 to perform downward displacement of the upper contact piece 11 in the preceding stage, and the bending support portion 15 of the lower contact piece 10 is moved. The upper contact piece 11 is brought into contact with the inner surface 17 of the base, and the bending support portion 15 after the contact is used as the second displacement fulcrum P.
The lower displacement of the latter stage is performed. That is, from the first displacement fulcrum P1 of the bending portion 11 at the horizontal U to the second displacement fulcrum P of the bending support portion 15
By shifting to the second position, the spring length between the second displacement fulcrum P2 and the tip of the lead mounting piece 15 of the upper contact piece 11 is set short to increase the elasticity of the upper contact piece 11, and at the same time, the load at the time of downward displacement is increased. It is carried on the inner surface of the lower contact piece 10.

In both of the above-mentioned embodiments, the displacement fulcrum P or P2 of the upper contact piece 9 is set to the lower contact piece 10 at the time of downward displacement of the upper contact piece 9 to obtain the final contact pressure with the IC lead.
By forming the bending support portion 15 which is brought into contact with the inner surface 17 of the base portion, the elasticity of the upper contact piece 9 is enhanced to achieve highly reliable pressure contact with the IC lead 4b. By setting the bending support portion 15 as the displacement fulcrum P or the second displacement fulcrum P2, the lead mounting contact piece 12 of the upper contact piece 9 and the IC
The variations in the contact points and contact pressure with the leads 4b are absorbed to a negligible range, whereby the final contact pressure between the IC lead 4b group and the contact 3 group can be made uniform.

The horizontal U-shaped bending contact 3 has horizontal U-shaped bending portions 11 along both sides of the mounting base 5 of the socket body 1, and the lead mounting contact piece 12 of the upper and lower contact pieces 9 and 10 and the surface mounting piece. 14 is provided so as to project from the side edge of the socket body 1, and the lower contact piece 10 is pressed into the contact insertion groove 6 or the like to be planted. At this time, the bending support portion 15, that is, the displacement fulcrums P and P2
Exists within this press-fitting area.

The height of the horizontal U-shaped bent portion 11, that is, the outer diameter can be reduced to near the limit of plastic deformation to make the height of the socket body 1 small.

The horizontal U-shaped bent contact 3 planted in the socket body 1 is soldered to the conductive pattern of the wiring board 13 after soldering the surface mounting contact piece 14 of the lower contact piece 10.
Mount the package 4 and contact the IC lead 4b 3
Then, the pressing cover 2 is attached and the pressing portion 2'of the cover 2 is mounted on the IC lead 4b.

When the IC lead 4b is pushed down by the presser cover 2, the lateral U-shaped bent contact 3 becomes lower contact piece 10.
The bending support portion 15 that comes into contact with the inner surface of the base of the displacement fulcrum P, P
2, the upper contact piece 9 is displaced downward against elasticity, the lower surface of the body 4a of the IC package 4 contacts the upper surface of the mounting table 5 of the socket body 1, or the lower surface of the body 4a of the IC package 4 is a horizontal U-shaped contact. When the upper contact piece 9 comes into contact with the upper side surface of the lateral U-shaped bent portion 3 of 3, the downward displacement of the upper contact piece 9 is completed, and the final contact pressure is obtained.

[0032]

According to the present invention, the spring length of the upper contact piece extending from the bending support portion is shortened to increase the spring constant of the upper contact piece, and even if the bending support portion is a fulcrum, it is large. Contact pressure can be obtained.

Further, since the level of the lead mounting piece of the upper contact piece can be set on the basis of the contact position of the lower contact piece of the bending support part, the level variation of the lead mounting piece can be eliminated as much as possible. The contact pressure with the lead can be made uniform.

Further, the downward displacement fulcrum of the upper contact piece, especially the displacement fulcrum when the spring pressure increases toward the latter stage, is not applied to the horizontal U-shaped bent portion as in the conventional case, but is provided on the bending support portion adjacent thereto. By shifting, it is possible to solve the problem of stress accumulated and accumulated in the horizontal U-shaped bent portion due to repeated displacement of the upper contact piece, and prevent the lateral U-shaped bent portion from being settled.

Further, as described above, since the horizontal U-shaped bent portion has a structure in which the downward displacement fulcrum is not used in the subsequent displacement stroke where the elasticity is maximized, the horizontal U-shaped bent portion has its curvature up to the limit of plastic deformation. Alternatively, the diameter can be made smaller than the limit and the volume can be made small. As a result, it is possible to form a contact in which the displacement amount of the upper contact piece is large, and at the same time, the lateral U
The IC socket main body on which the bent contact is implanted can be made smaller (thinner), and as a result, the mounting height of the IC socket can be made smaller as a whole.

[Brief description of drawings]

FIG. 1 is a sectional view showing an IC socket for surface mounting showing an embodiment of the present invention, and FIGS. 1A to 1D are sectional views showing a pressure contact process of an IC package mounted in the socket.

2 shows a main body of the surface mounting IC socket shown in FIG. 1, (A) is a plan view of the IC socket main body, (B) is a front view thereof, and (C) is a side view thereof.

FIG. 3 is a perspective view showing a horizontal U-shaped bent contact to be embedded in the surface mounting IC socket body.

4A to 4D are diagrams showing a downward displacement process of an upper contact piece of the horizontal U-shaped bent contact shown in FIG.

FIG. 5 shows another example of a horizontal U-shaped bent contact, and FIGS. 5A to 5D are diagrams showing a downward displacement process of an upper contact piece on which an IC lead is mounted.

FIG. 6A is a cross-sectional view of a surface mounting IC socket showing a conventional example, FIG. 6B is a perspective view of a lateral U-shaped bent contact to be implanted in this socket, and FIG. 6C is a side view.

[Explanation of symbols]

 1 IC Socket Main Body 2 IC Press Cover 3 Horizontal I-shaped Bent Contact 4 IC Package 4a IC Package Body 4b IC Lead 9 Upper Contact Piece 10 Lower Contact Piece 11 Horizontal U-shaped Bent Section 12 Lead Mounting Piece 13 Wiring Board 14 Surface Mount Contact piece 15 Bending support 18 Gap P Displacement fulcrum P1 1st displacement fulcrum P2 2nd displacement fulcrum

Claims (3)

[Claims] 1. A contact is formed by bending a strip into a substantially horizontal U-shape and extending in the horizontal direction through the horizontal U-shaped bent portion and having an upper contact piece and a lower contact piece that are vertically opposed to each other. , The contacts are arranged in parallel along the lower edge of the IC socket main body so that the horizontal U-shaped bent portion is on the inside, and the free end of the lower contact piece is soldered to the conductive pattern surface of the wiring board. Forming a contact piece for the upper contact piece and I
A surface mounting IC socket in which a lead mounting piece for mounting a lead of a C package is formed, and the lead mounting piece is displaced downward against the elasticity of the upper contact piece to make pressure contact with the IC lead. , The base portion of the upper contact piece is bent downward to form a bending support portion, and the lower surface of the top of the bending support portion is brought into contact with the inner surface of the base portion of the lower contact piece,
A surface mounting IC socket, characterized in that the bending support portion forms a displacement fulcrum at the time of downward displacement against the elasticity of the upper contact piece. 2. A contact is formed by bending a strip into a substantially horizontal U-shape and extending in the horizontal direction through the horizontal U-shaped bent portion and having an upper contact piece and a lower contact piece that are vertically opposed to each other. , The contacts are arranged in parallel along the lower edge of the IC socket main body so that the horizontal U-shaped bent portion is on the inside, and the free end of the lower contact piece is soldered to the conductive pattern surface of the wiring board. Forming a contact piece for the upper contact piece and I
A surface mounting IC socket in which a lead mounting piece for mounting a lead of a C package is formed, and the lead mounting piece is displaced downward against the elasticity of the upper contact piece to make pressure contact with the IC lead. Bending the base portion of the upper contact piece downward to form a bending support portion, and forming a gap between the lower surface of the top portion of the bending support portion and the inner surface of the base portion of the lower contact piece to form the horizontal U-shaped bend. Part forms a first displacement fulcrum at the time of downward displacement of the front part of the upper contact piece, and the lower surface of the top of the bending support part is brought into contact with the inner surface of the lower contact piece by the downward displacement of the front part. A surface mounting IC socket, characterized in that the bending support portion forms a second displacement fulcrum when the upper contact piece is displaced downward in the subsequent stage. 3. The surface mounting IC socket according to claim 1, wherein the inner diameter of the horizontal U-shaped bent portion is formed to be equal to or less than the plate thickness of the upper and lower contact pieces.