JPH07161900A - Surface mount type semiconductor package - Google Patents

Abstract

PURPOSE:To widen the lead-row-direction intervals of pads on a printed wiring board side corresponding to leads maintaining a density, and to raise the ratio of pattern wiring between them. CONSTITUTION:Two kinds of leads are provided side by side on both, right and left, side surfaces of a semiconductor package 10 alternately. The first kind is a lead 11 and is formed by bending into the shape of a letter Z, and its lower side part is a base part 11a to be connected and fixed. The second kind is a lead 12, and if it is a right-hand side one it is formed by bending in an intermediate part so that its base part 12a may be positioned near and at the right-hand outside of the base part 11a of an adjoining lower side lead 11. This intermediate part is bent into the shape of a crank. Accordingly, the pitches of respective base parts 11a and 12a of respective kinds leads 11 and 12 adjoining each other in the directions of the lead rows are twice as large as the former ones, since their intermediate ones are thinned out seemingly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape and arrangement of the leads so that the spacing between the pads on the printed wiring board side to which the leads are electrically connected and fixed can be widened and the pattern wiring rate can be improved in the meantime. The present invention relates to a surface mount type semiconductor package having improved.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIGS. FIG. 6 is a plan view of the same, FIG. 7 is a perspective view of an essential part thereof, and FIG. 8 is a plan view of an essential part of the printed wiring board. In FIG. 6, leads 31 are arranged in parallel on the left and right side surfaces of the semiconductor package 30. As shown in FIG. 7, the lead 31 is bent into a Z shape, and its lower side portion is used as a base portion 31a to be electrically fixed. The base portion 31 of this lead 31
The mating pad 32 to which a is conductively fixed is a conductive rectangular area formed together with the wiring pattern 33 on the printed wiring board 34, as shown in FIG.

In recent semiconductor packages, the pitch between leads is about 0.5 mm as seen in the example of SOP (Small Outline Package) in order to improve the mounting density of circuit components on the printed wiring board. It is narrowed to. However, as shown in Figure 8, the printed wiring board 34
The gap g between the adjacent pads 32 becomes narrower, and the wiring pattern 33 cannot be passed between them. If it is not done, a safe insulation distance cannot be guaranteed, which causes a quality problem. As an improvement measure, in the invention described in Japanese Patent Laid-Open No. 3-74866, there are two types of leads, one that extends outwardly and the other that extends shortly, and they are arranged alternately, and the pitch is the same in the direction of the lead row. However, it is devised to widen the space between adjacent pads.

[0004]

The invention described in Japanese Patent Application Laid-Open No. 3-74866 has an advantage that a space can be widened between adjacent pads and a wiring pattern can be inserted between them, but the leads can be used. Among them, the one that extends to the outer side has a problem that the occupied area is widened and the improvement of the mounting density is hindered.

The problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and to maintain the mounting density, the lead row of the printed wiring board side pad to which the leads should be conductively fixed. An object of the present invention is to provide a surface mount type semiconductor package in which leads are improved in shape and arrangement so as to widen the interval in the direction and improve the pattern wiring rate therebetween.

[0006]

A surface mount type semiconductor package according to a first aspect of the present invention has first and second leads alternately arranged on a side surface thereof, the first lead having a Z shape and a lower side thereof. And the second lead is bent at the middle portion so that the second lead is positioned close to the outer side of the base of the first lead on one side adjacent to the first lead. Formed.

According to another aspect of the surface mount semiconductor package of the present invention, first and second leads are alternately arranged side by side.
The first lead has a U-shape, and the lower side of the first lead serves as a base portion to be conductively fixed, and the second lead has the base portion on the outer side of the base portion of the first lead on one adjacent side. It is formed by bending in the middle part so as to be positioned close to each other.

[0008]

In the surface mount type semiconductor package according to the first aspect of the present invention, of the first and second leads arranged alternately on the side surface, the first lead is Z-shaped and the lower side portion thereof is conductively fixed. As the base portion to be formed, the second lead is bent and formed in the intermediate portion so that the base portion is located close to the outer side of the base portion of the first lead on one adjacent side, The pitch of the respective base portions of the first leads and the second leads that are adjacent to each other in the lead row direction and the corresponding pads are twice as large as that of the conventional one.

According to another aspect of the surface mount semiconductor package of the present invention, of the first and second leads arranged alternately on the side surface, the first lead is U-shaped and the lower side thereof is conductively fixed. As the base portion to be formed, the second lead is bent and formed in the intermediate portion so that the base portion is located close to the outer side of the base portion of the first lead on one adjacent side, The pitch of the respective base portions of the first leads and the second leads that are adjacent to each other in the lead row direction and the corresponding pads are twice as large as that of the conventional one.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a surface mount type semiconductor package according to the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of the first embodiment, FIG. 2 is a perspective view of a main part thereof, and FIG. 3 is a plan view of a main part of the printed wiring board. In FIG. 1, a lead row is provided on each of the left and right side surfaces of the semiconductor package 10, and there are two types of leads, a first lead and a second lead, which are alternately arranged side by side. First is the lead
At 11, the base portion 11a is bent and formed in a Z shape, and its lower side portion is used as a base portion 11a to be conductively fixed. The second is lead 12,
Speaking of the right side, the base portion 12a is bent and formed at the intermediate portion so as to be located close to the right outside of the base portion 11a of the adjacent lower lead 11. As shown in Fig. 2, the bending of this intermediate part is made into a crank shape.

Therefore, the bases 11a, 12a of the leads 11 adjacent to each other in the lead row direction and the leads 12 adjacent to each other are formed.
The pitch of the middle is thinned out,
It is twice as much as the conventional one. Correspondingly, as shown in FIG. 3, in the printed wiring board 1, the base portions 11a and 12a of the leads 11 and 12 are to be electrically conductively fixed to the pads 11b and 12b.
In b, the distance between the adjacent elements in the lead row direction is G.
Therefore, the distance of the intermediate one is significantly thinned and becomes much wider than the conventional distance (see the distance g in FIG. 8).

FIG. 5 is a plan view of the second embodiment, and FIG.
It will be described with reference to a perspective view of the main part of FIG. In FIG. 4, lead rows are provided on each of the left and right side surfaces of the semiconductor package 20, and there are two types of leads, the first and second types, which are alternately arranged in parallel. The first is a lead 21, which is bent and formed in a U-shape as shown in FIG. 5, and has a lower side portion as a base portion 21a to be conductively fixed. The second is lead 22,
Speaking of the right side, the base portion 22a is bent and formed at an intermediate portion so as to be located close to the right outside of the base portion 21a of the adjacent lower lead 21. The bending of the intermediate portion is made into a crank shape as shown in FIG. Therefore, the pitches of the base portions 21a, 22a between the leads 21 adjacent to each other in the lead row direction and between the leads 22 are such that the intermediate ones are thinned out. Similarly, it is twice as large as that of the conventional one, and the spacing between the corresponding pads is also widened.

Differences in features between the first embodiment and the second embodiment will now be described. In the first embodiment, one lead 11
Since the base portion 11a of B is bent outward, the amount of protrusion of the other lead 12 to the outside becomes large, which has the disadvantage of occupying a larger area. On the other hand, it is easy to inspect the state of conduction fixation of the leads 11 and 12. The quality can be fully guaranteed. In the second embodiment, since the base portion 21a of one lead 21 is bent inward, the amount of protrusion of the other lead 22 to the outside becomes small, which has the advantage that the occupying area can be kept small. It is rather difficult to inspect the state of continuity and fixation of the leads 21, and there is a possibility that sufficient quality assurance may be slightly hindered.

[0014]

In the surface mount type semiconductor package according to the first or second aspect of the present invention, the base portions of the first leads and the second leads, which are adjacent to each other in the lead row direction, and the pitch of the corresponding pads are provided. However, it is twice as much as the conventional one. Therefore, while maintaining the mounting density, the distance between the pads on the side of the printed wiring board to which the leads are to be conductively fixed is expanded nearly twice, and consequently the pattern wiring rate during that time can be improved or the abnormality occurrence rate due to the pattern contact can be reduced. . The difference between the two is that, in the surface mount type semiconductor package according to claim 1, the first lead is bent outward, so that it is easy to inspect the state of conduction fixation of the first lead, and sufficient quality assurance can be ensured. On the other hand, in the surface mount type semiconductor package according to the second aspect, since the first lead is bent inward, the amount of protrusion to the outside is reduced as a whole, and the occupied area is suppressed to that extent.

[Brief description of drawings]

FIG. 1 is a plan view of a first embodiment according to the invention.

FIG. 2 is a perspective view of a main part of the first embodiment.

FIG. 3 is a plan view of a main part of the printed wiring board according to the first embodiment.

FIG. 4 is a plan view of a second embodiment according to the invention.

FIG. 5 is a perspective view of an essential part of the second embodiment.

FIG. 6 is a plan view of a conventional example.

FIG. 7 is a perspective view of a main part of a conventional example.

FIG. 8 is a plan view of a main part of a conventional printed wiring board.

[Explanation of symbols]

 1 printed wiring board 2 wiring pattern 10 semiconductor package 11 lead (first) 11a base portion 11b pad 12 lead (second) 12a base portion 12b pad 20 semiconductor package 21 lead (first) 21a base portion 22 lead (second) 22a base part

Claims (2)

[Claims] 1. A first lead and a second lead are alternately arranged side by side on a side surface, the first lead is Z-shaped, and a lower side portion thereof is a base portion to be conductively fixed, and the second lead is A surface mount type semiconductor package, characterized in that the base portion is bent and formed in an intermediate portion so that the base portion is located close to the outer side of the base portion of the first lead on one adjacent side. 2. A first side and a second side are alternately arranged side by side on the side surface, the first lead is U-shaped, and the lower side thereof is a base portion to be conductively fixed, and the second lead is A surface mount type semiconductor package, characterized in that the base portion is bent and formed in an intermediate portion so that the base portion is located close to the outer side of the base portion of the first lead on one adjacent side.