JPH04355955A - Lead pin for pin grid array - Google Patents

Abstract

PURPOSE:To enable brazing materials which are pre-bonded to be formed uniform in shape by a method wherein a ball-shaped brazing material is put on a pin grid array lead pin head put in a jig and fused by heating. CONSTITUTION:A recess 13 is provided to the upside 12 of a lead pin 1 head which is fixed to a pin grid array, board, and a ball-shaped brazing material is put in the recess 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to lead pins for pin grid arrays (hereinafter referred to as "PGA"), and particularly to lead pins with brazing material.

0002

2. Description of the Related Art When soldering a lead pin to a ceramic substrate such as a PGA, for example, a lead pin with a solder material attached to its tip is widely used in consideration of uniform, high-quality soldering and workability. By the way, as a method of attaching brazing material to a lead pin, as shown in FIG. 3(a),
Place an appropriate amount of spherical brazing material (3) on the flat head (11) of the lead pin (1) fitted in the jig (2) so that it will not overflow or become insufficient, resulting in insufficient bonding, and heat it. By doing this, the solder metal (3) is attached to the lead pin head (11).
In this case, in order to ensure good bonding of the pin to the substrate etc., the shape of the brazing material (3) bonded to the pin head (11) must be as shown in Figure 3(b). It is desirable that the shape be symmetrical and well-balanced.

0003

[Problem to be Solved by the Invention] However, in order to obtain a four-sided symmetrical shape as described above, it is necessary to position the brazing material (3) at the center of the upper surface of the head (11). . However, since the soldering material (3) is spherical and the head (11) of the lead pin (1) on which it is placed is flat, the soldering material (3) is slightly bent as shown in Fig. 4(a). In addition, it is difficult to move the lead pin (1) back and forth, left and right on the head (11) surface, and to position it at the center of the head (11) surface as expected. For this reason, when heated and melted, it is difficult to form a four-sided symmetrical shape as described above, especially when the brazing material (3) is heated in a state where it is in contact with the wall of the jig (2) that holds the lead pin (1). When melted, the heat applied to the brazing material (3) is absorbed by the jig (2). As a result, uniform heating and melting is no longer carried out, and for example, as shown in Figure 4(b), the brazing material (3) is biased to one side, resulting in an uneven shape on all sides, or protrusions appear as shown in Figure 4(c). (31) or a shape with corners. Therefore, when such pins are bonded to a substrate, the brazing material overflows, and uniform and high-quality fixation to the substrate etc. cannot be expected, and workability is also poor, which is a problem to be solved.

0004

[Means of the present invention for solving the problems] The present invention aims to solve the above problems, and its purpose is to provide the following means:
That is, this can be achieved by providing a depression in the center of the upper surface of the head of the lead pin.

[0005]

[Operation] By doing the above, the spherical brazing material settles in the center of the upper surface of the head of the lead pin, and will not move from that location even if some vibration is applied from the outside. Therefore, when heated and melted, the brazing material assumes a well-balanced shape with four-sided symmetry as shown in FIG. 3(b), and can be bonded to a substrate etc. uniformly and with high quality. Next, examples of the present invention will be described.

[0006]

[Example] Figures 1(a) and 1(b) are perspective views and partial cross-sectional views of a PGA lead pin according to the present invention.
There is a depression (13) in the center of the upper surface (12) of the head (11).
) is provided. Head of lead pin (1) (11)
Although the shape is often a disk as shown in FIG. 1, it is not limited to this, and there are various shapes such as a square plate, a triangular plate, etc. depending on design and manufacturing considerations. To give a specific example of the dimensions of a generally well-known lead pin, in Figure 1, the lead pin has a diameter of 0.5 mm and a length of 10 to 10 mm.
The diameter of the head is 1.5mm, and the thickness is 20mm.
It has a disc shape of about 0.5 mm and is made of Fe, Ni.
, Co, etc., and the surface is often solder-plated or Au-plated. Further, as the brazing material, a spherical material having a diameter of about 0.3 to 0.5 mm and made of an alloy consisting of two or more metals such as Ag, Au, Pb, Ni, and Ge is often used. The shape of the recess provided on the top surface (12) of the head of the lead pin (1) is not limited to a circle as shown in FIG. 1, but may be a cone, a square pyramid, or a shape as illustrated in the plan view of FIG.
It may be any shape such as a triangular pyramid, an octagonal pyramid, or a star shape. In addition, the depth (d) of the recess provided in the head (11) of the lead pin (1) (see Figure 1(b)) is set to such an extent that the brazing material placed on the head (11) does not move from the recess during the heating process. For example, the wax material (3) has a diameter of about 1.5 mm.
If the shape is spherical, the depth of the depression should be 0.2 to 0.7.
If it is within the range of mm, the purpose can be sufficiently achieved. In addition,
Care must be taken so that the volume of the depression does not become larger than the volume of the brazing material (3). Also, the size of the depression D
(See Fig. 1(b)) For example, when the soldering material (3) is spherical, it is best to make the soldering material (3) large enough so that there is no play in the so-called depression, and the depth of the depression and It is determined by the relationship between Further, the recessed portion of the head of the lead pin may be provided by any means. For example, when a lead pin is manufactured from a wire material by press working, a protrusion for a recess or the like may be provided on a press mold for the press working. In this way, just by adding processing to the mold,
The desired product can be manufactured without special modifications to conventional manufacturing methods.

[0007]

Effects of the Invention Since the present invention has the structure and operation described above, it exhibits the following unique and remarkable effects. 1. The brazing material that has fallen into the head of the lead pin will not move even if vibrations are applied from the outside, for example. Therefore, even if unexpected troubles such as slight vibrations occur during the heating and melting process, there will hardly be any defective products such as lead pins with brazing material having an inconvenient shape. 2. Since the recess provided in the head of the lead pin can be provided at any position, it is possible to prevent the brazing material from coming into contact with the wall of the jig during heating and melting, and the heat applied to the brazing material (3) can be prevented from coming into contact with the wall of the jig. The lead pin with solder material is uniformly heated and melted without being taken away by the jig (2), and has no protrusions or corners. Therefore, a uniform high-quality solder weld can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a PGA lead pin of the present invention.

FIG. 2 is a diagram showing another example of a spherical brazing material joining depression.

FIG. 3 is an explanatory diagram of a conventional method of joining a brazing material onto the head of a PGA lead pin and a desirable joining shape of the brazing material.

FIG. 4 is an explanatory diagram of the reason for the malfunction of the conventional brazing material joining means and an example of the shape of the joining brazing material.

[Explanation of symbols]

(1) Lead pin (11) Lead pin head (2) Jig (3) Brazing material (31) Corner (12) Top surface of lead pin head (13) Hollow

Claims (1)

[Claims] 1. A pin grid array lead pin comprising a head and a lead portion that are fixed to a substrate of the pin grid array, the pin grid array having a recessed portion on the surface of the head that is fixed to the substrate. lead pin.