JP3294738B2 - Lead pin mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor device, package, relates to a mounting structure for Ridopi down to be used for the substrate.

[0002]

2. Description of the Related Art PGA is commonly used for semiconductor device packages.
(Pin Grid Array) type package. This PGA type package has a structure in which a number of lead pins are erected on a substrate constituting a package body. And
In a PGA type package having a resin substrate as a constituent member, the rear end of the lead pin is pressed into a through hole provided on the resin substrate and plated on the inner wall surface, and then soldered. Thus, the lead pins are erected on the substrate. Note that the resin substrate includes a printed substrate mainly formed by providing a copper foil pattern on an epoxy substrate reinforced by glass cloth.

When a rear end portion of a lead pin is inserted into and fixed to a through hole of a printed circuit board, in order to obtain high pull-out resistance only by press-fitting, the through-hole is deformed and the elastic force accompanying the deformation is reduced by the lead pin. Is used as a fixing force for fixing. And to get a strong fixing force,
It is preferable that the rear end of the lead pin has a flattened shape and the cross-sectional shape of the through hole press-fit at the rear end is changed to an elliptical shape. For this reason, conventionally, as shown in FIGS. 5 and 6, the rear end 52 of the lead pin 50 is simply formed flat.

[0004]

In order to obtain a higher pull-out resistance, the length of the rear end portion 52 of the lead pin 50 in the axial direction is longer than the thickness of the printed circuit board 20, and the rear end portion 52 is formed through the rear end portion 52. The hole 22 may be inserted over the entire length, but there is a problem that the formation of the meniscus 30 of the solder is not suitably performed at the time of soldering. The meniscus is necessary for improving the pull-out resistance of the printed circuit board 20 and the lead pins 50 and improving the reliability of the electrical connection. The reason that the meniscus 30 is not preferably formed is that the gap between the inner wall surface 38 of the through hole 22 and the outer surface of the rear end portion (the uneven surface 54) of the lead pin 50 is partially increased, and the uneven surface 54 and the land This is because the surface tension cannot be applied evenly at the time of soldering because the distance between the inner peripheral edge 26a and the inner peripheral edge 26a is different in each part. The meniscus 30
Is a portion in which the solder 28 is formed in a substantially conical shape by surface tension between the outer periphery of the lead pin 50 and the ring-shaped upper surface of the land 26 as the bottom peripheral edge.

An object of the present invention is press-fitted into the through hole of the substrate or the like, when it is soldered, Ridopi emissions formed to suitable meniscus of the solder can be obtained
The object of the present invention is to provide a lead pin mounting structure in which a suitable solder meniscus is formed by soldering.

[0006]

The present invention has the following arrangement to achieve the above object. That is, the present invention is formed in a pin shape with a tip portion connected to an external circuit .
Lead pin, is pressed into the through-hole plating on the inner wall surface has been subjected rear end thereof provided on a substrate made of tree fat,
With Ru Tei is erected on the substrate, or the through hole
A mounting structure for a lead pin, wherein a cross-sectional shape of a portion protruding from the through hole is substantially circular.
The plating that forms the inner wall surface of the edge is
Are thickly than the intermediate portion, pressure to the through hole
The rear end of the inserted lead pin is formed flat, the length in the axial direction is shorter than the depth of the through hole, and the inner end near the lower end of the through hole is formed .
The rear end of the rear end is pressed against the plating thick on the wall.
And the rear end is brazed by solder.
Characterized in that that.

Further , the present invention is connected to an external circuit.
A lead pin formed in a pin shape with a tip portion is
The rear end is provided on a resin substrate and the inner wall is plated.
It is pressed into the through-hole which is being erected on the substrate
And the part protruding from the through hole is cut.
Lead pin mounting structure with a substantially circular surface shape
A lead pin press-fitted into the through hole.
The rear end is substantially cross-shaped in cross section, and one direction of the cross
Part is formed longer than the part in the other direction that is substantially orthogonal,
Both ends of the one-way portion forming the cross shape are through holes.
And press the inner wall of the
To prevent the inner wall of the through hole from being pressed,
Each part is formed, and the depth of the through hole
The cross-shaped rear end, which is shorter than the
Characterized by being brazed by:

[0008]

According to the lead pin used in the present invention, the rear end portion is formed flat and the length of the rear end portion in the axial direction is shorter than the depth of the through hole. When this is done, the rear end can be completely immersed in the through hole. Moreover, the lower end of the through hole
After plating on the inner wall surface near the lead pin
The rear end of the end is press-fitted, so the lead pin is securely
Can be erected. Furthermore, since the rear end of the flatly formed lead pin completely enters the through-hole, the cross-sectional shape of the part of the lead pin that protrudes outside the through-hole is:
It has a substantially circular shape. Accordingly, the interval between the inner peripheral edge of the land on the meniscus formation side by soldering and the outer periphery of the lead pin at the portion protruding outside the through hole becomes equal over the entire circumference. Therefore, at the time of soldering, a uniform surface tension acts on the entire surface between the surface of the land and the outer peripheral surface of the lead pin, and a suitable meniscus of the solder is obtained. Ma
The shape of the rear end is substantially cross-shaped in cross section, and the cross
The part in one direction of the shape is longer than the part in the other direction that is almost orthogonal
The two ends of the unidirectional part
-While pressing the inner wall of the hole, both ends of the part in the other direction
So that the inner wall of the through hole does not press against
By using a lead pin with a formed part,
The clearance between the inner wall of the through hole and the lead pin is suitably small.
Reduce the amount of solder to be filled
be able to.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing a state in which an embodiment of a lead pin according to the present invention is fixed to a substrate (lead pin mounting structure), and FIG. 2 is a bottom view of FIG. FIG. 3 is a sectional view taken along line AA of FIG. In this embodiment, a lead pin used in a package for a PGA type semiconductor device having a printed board and a mounting structure thereof will be described. Reference numeral 10 denotes a lead pin, which is formed in a pin shape with a tip 11 connected to an external circuit. The rear end portion 12 of the lead pin 10 is formed flat and has a length in the axial direction shorter than the depth of the through hole 22.

The printed board 20 is formed by providing a circuit pattern made of a metal foil such as a copper foil on an epoxy board reinforced mainly by a glass cloth. The printed circuit board 20 is provided with a through hole 22 having a diameter slightly smaller than the width of the flat rear end portion 12. Through hole 22
Has a plating 24 such as copper plating on the inner wall surface.
The plating 24 is provided continuously and integrally with a land 26 formed in a ring shape around the through hole 22 on both sides of the printed board 20.

The lead pins 10 are erected on the printed circuit board 20 by inserting the rear ends 12 thereof into the through holes 22. Since the diameter of the through hole 22 is formed to be smaller than the width of the rear end portion 12, the rear end portion 12 is press-fitted into the through hole 22 and the lead pin 10 can be reliably erected. . More specifically, in the present embodiment, as shown in FIG. 1, the plating 24 easily adheres to both end edges of the through hole 22, and is provided on the inner peripheral surface 24 a of the plating 24 near the lower end edge of the through hole 22. End 1
2, the rearmost end portion 12a is strongly press-fitted. The press-fitting of the lead pin 10 deforms the through hole 22 into an elliptical shape, and the lead pin 10 is fixed in an upright state by an elastic force generated by the deformation.

Next, a description will be given of a semiconductor device package on which the lead pins 10 which are one mode of the “lead pin mounting structure” are erected, together with the manufacturing process thereof. First, the rear end portion 12 of the lead pin 10 is press-fitted (inserted) into the through hole 22 of the printed circuit board 20 and is erected on the printed circuit board 20 as described above. At this time, since the length of the rear end portion 12 in the axial direction is shorter than the thickness of the substrate, the rear end portion 12 can be completely immersed in the through hole 22.

Next, the lead pins 10 are soldered to the printed circuit board 20 at the rear end portion 12. Generally, this soldering is performed by mounting a printed circuit board 20 on which a lead pin 10 is press-fitted at a rear end portion 12 into molten solder.
This is done by dipping. In addition, as another soldering method, a washer-shaped solder is disposed on a corresponding portion, or a solder is printed on a corresponding portion, and the molten solder is heated and reflowed, so that a molten solder is formed on a lead pin. There is a method of soldering by flowing into the through hole 22 into which 10 is press-fitted.

The rear end portion 12 formed flat as described above.
Penetrates into the through hole 22, the through hole 2
The cross-sectional shape of the portion of the lead pin that protrudes outward from the outside 2 is substantially circular. Therefore, the inner peripheral edge 26a of the land 26 and
Lead pin 1 at a portion protruding outside through hole 22
The distance from the outer circumference 10a becomes equal over the entire circumference. For this reason, at the time of soldering by the above-mentioned method, a uniform surface tension acts on the entire periphery between the surface of the land 26 and the outer periphery 10a of the lead pin 10, and a suitable meniscus 30 of the solder 28 is obtained. Can be

The shape of the rear end portion 12 of the lead pin 10 can be formed by various methods, but in order to reduce the manufacturing cost, the rear end portion 12 is formed by pressing a wire having a circular cross section. do it. When the wire is crushed by this press working, the cross-sectional area of the rear end portion 12 can be formed so as to be larger than the cross-sectional area of the wire having a circular cross-section. With a small amount of solder, a suitable meniscus 30 can be obtained.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 4 is a sectional view of the rear end. As in the above embodiment, the length of the rear end portion 32 in the axial direction is shorter than the depth of the through hole, and the rear end portion 32 is formed to have a substantially cross-shaped cross section. The following effects can be obtained by forming the portion 34 in one direction to be longer than the portion 36 in the other direction that is substantially orthogonal. First, only the one-way portion 34 having a substantially cruciform cross section can be strongly pressed against the inner wall surface 38 of the through hole, and a high pull-out resistance of the lead pin with respect to the through hole can be obtained. The cross-shaped portion in the other direction can fill the gap between the through holes, and can eliminate a portion where the distance between the outer surface of the rear end portion 32 and the inner wall surface 38 of the through hole becomes large. Therefore, a more suitable meniscus can be obtained with a small amount of solder in soldering.

In the above embodiments, the lead pin used in the package for the semiconductor device has been described. However, the lead pin and its mounting structure according to the present invention can be suitably used for various semiconductor devices, packages, substrates, and the like. Of course. Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited to the embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. .

[0018]

According to the mounting structure of the lead pin of the present invention, the rear end portion of the lead pin, the axial length of that is, because it is shorter than the thickness of the substrate, the rear end portion of the lead pin By entering the through hole, the distance between the inner peripheral edge of the land and the outer periphery of the lead pin at a portion protruding outside the through hole becomes equal over the entire circumference. For this reason, at the time of soldering, a uniform surface tension acts on the entire surface between the surface of the land and the outer peripheral surface of the lead pin,
A favorable meniscus of the solder is obtained, so that the pull-out strength between the substrate and the lead pin can be improved, and the reliability of the electrical connection can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a lead pin mounting structure according to the present invention.

FIG. 2 is a bottom view of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the lead pin according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional example of a lead pin mounting structure.

FIG. 6 is a sectional view taken along line XX of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Lead pin 12 Rear end 20 Printed circuit board 22 Through hole 24 Plating 26 Land 28 Solder 30 Meniscus

Claims (2)

(57) [Claims] 1. A lead pin formed with a tip portion to be connected to an external circuit pins shaped, its rear end is plated on the inner wall surface provided on a substrate made of tree fat is applied through is pressed into the hole, with Ru Tei is erected on the substrate, the cross-sectional shape is substantially circular portion protruding from said through hole
A lead pin mounting structure formed on the inner surface of the through-hole , wherein the plating forms inner wall surfaces at both ends of the through-hole.
Is thicker than the middle part of the through hole.
Ri, the rear end portion of the lead pin which is press-fitted into the through hole,
The through hole is formed to have a flat length that is shorter than the depth of the through hole.
Plating on the inner wall near the lower end of the
A lead pin mounting structure , wherein a rear end of the rear end is press-fitted and the rear end is brazed by solder . And a tip portion connected to an external circuit.
Pin-shaped lead pins, the rear end of which is made of resin
Through-holes that are provided on
And is protruded from the through hole, and has a substantially circular cross section.
The lead pin mounting structure is formed at the rear end of the lead pin pressed into the through hole ,
A cross section cruciform, its cross unidirectional site is formed longer than the other direction of the portion substantially perpendicular, both ends of the portion of one-way forming the cross is Suruho
And press the inner wall of the
To prevent the inner wall of the through hole from being pressed,
A cross section in which each part is formed and formed to be shorter than the depth of the through hole
A lead pin mounting structure , characterized in that the rear end of the substantially cross shape is brazed by solder .