JPH03206647A - Resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To arrange tip parts on the same plane by a method wherein parts corresponding to shoulder parts of outer leads extended in parallel with a mounting face from side faces of a resin body are covered with resin protrusions and are fixed, the leads are bent from the protrusions while the protrusions are gripped lightly in such a way that they are not deformed by pads and by pressure faces of a die and their tips are bent back. CONSTITUTION:Boundary parts between shoulder parts 3a and intermediate parts 3b of outer leads 2 extended in parallel with a mounting face 4b from side faces 4a are covered with resin protrusions 1a and are fixed; they are situated in the protrusions 1a in the intermediate parts 3b and the leads 2 are bent. The leads 2 are shaped by using a metal mold. At this time, while the protrusions 1a are gripped by using pressure faces 8 of a die and edges of pads 6 in such a way that the protrusion 1a is not deformed; the leads 2 are bent near the protrusions 1a in order to prevent the leads 2 from being bent back when the shoulder parts 3a are sprung back. Consequently, tip parts 3c of the leads 2 are situated on the same plane. Even when the tip parts 3c are bent back, their height becomes uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin-sealed semiconductor device (hereinafter abbreviated as IC), and particularly to improving the flatness of an external lead mounting surface of a flat package.

[Conventional technology]

Conventionally, as an example of IC, a semiconductor chip is bonded to the center of a lead frame having external leads, and the input/output terminals of the bonded semiconductor chip and the internal leads connected to the external leads are connected with thin metal wires. The structure was sealed with resin to protect it from the outside air. FIG. 4 is a side view of an IC showing an example of a conventional IC. As shown in the figure, this IC has a plurality of external leads 2 protruding outward from a side surface 4a of a resin body 1 containing a semiconductor chip, and these external leads 2 extend parallel to a mounting surface 4b. An elliptical shape is formed by a shoulder portion 3a that is bent downward from the shoulder portion 3a, an intermediate portion 3b that is bent downward from the shoulder portion 3a, and a tip portion 3c that is bent back from the intermediate portion 3b so as to protrude from the mounting surface 4b and be approximately parallel to this surface. has been completed.

When this IC is mounted on a printed circuit board, although not shown in the drawing, while aligning the surface of the tip 3c of this external lead with the pre-soldered wiring pad of the corresponding printed circuit board, Soldering was performed by heating with a lamp or the like to melt preliminary solder.

Next, a method of bending the external leads of this IC will be explained. Fifth
Figures (a) and (b) show a cross-sectional view of an IC external lead mold and a cross-sectional view taken along the line C-C. First, the mold is opened and one half of the resin body 1 of the IC is inserted into the recess 10a of the die 5. Next, the pad 6 is lowered and the resin body l is inserted into the recess 10b of the pad 6.
Cover with one half. At the same time, the end surface of the pad 6 presses and holds the shoulder portion 3a of the external lead against the pressing surface 8 of the die 5. Next, the punch 7 is lowered to bend the unformed external lead 2a extending outward as indicated by the broken line. Furthermore, at the same time, the tip 3C of the external lead 2 is sandwiched between the molding surface of the die 5 and the punch 7 and bent back to make the surface of the tip 3c almost parallel to the mounting surface 4b of the resin body 1, and from this surface. I was molding it as if I were going on a business trip.

[Problem to be solved by the invention]

FIGS. 6(a) and 6(b) are side views of each IC after resin sealing and after bending the external leads. During the process of manufacturing this IC, when the assembled semiconductor chip and lead frame are sealed with resin, the part molded by the upper mold of the resin body 1 is exposed to outside air immediately after opening the resin mold. Because it is exposed to heat, it cools and shrinks faster than the part molded with the lower mold. For this reason, the resin body 1 is warped as shown in FIG. 6(a). Also,
As the resin body 1 warps, the line connecting the cross-sectional centers of the plurality of external leads 2 also becomes a state in which the external leads 2 are warped toward both ends of the resin body 1.

The external lead 2 of the conventional IC described above is formed by holding the warped shoulder 3a of the external lead between a die 5 and a pad 6 having a flat cross-sectional shape as shown in FIG. 5(b). Since the shoulder portion 3a of the external lead holding the tip 3c of the external lead springs back, the external lead 2 at both ends follows the warp of the resin body 1 as shown in FIG. 6(b). It has been returned to its inverted state. The warping of the tips 3c of the external leads due to the warping of the resin body 1 creates a gap between the wiring pad of the printed circuit board and the tips of the external leads when the IC is mounted on the printed circuit board. This causes the problem of not being soldered.

An object of the present invention is to provide an IC in which the tips of external leads are flush with each other even if the resin body is warped.

[Means to solve the problem]

The present invention has a plurality of external leads protruding outward on the side surface of a resin body containing a semiconductor chip, and the external leads have a shoulder portion extending parallel to a mounting surface of the resin body and a portion below the shoulder portion. In a resin-sealed semiconductor device, the resin-sealed semiconductor device is configured with a middle part bent downward to a position of 100 degrees, and a tip part protruding from the mounting surface and bent back downward from the middle part so as to be substantially parallel to the mounting surface. A boundary between a shoulder portion of the external lead extending parallel to the attachment surface from a side surface of the body and the intermediate portion is covered and fixed with resin, and the intermediate portion covers and fixes the shoulder portion of the external lead. It is characterized by having an external lead bent downward from the edge of the resin.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 and FIG. 6(c) are side views of an IC showing a first embodiment of the present invention. The difference between this embodiment and the conventional example is that the boundary between the shoulder portion 3a of the external lead and the intermediate portion 3b, which conventionally extended from the side surface 4a in parallel to the mounting surface 4b, is covered and fixed with a resin protrusion 1a, and the external lead The intermediate portion 3b is bent from the resin protrusion 1a. The external leads of this IC are molded using a mold as shown in FIG. However, since the external lead 2 is bent from the resin protrusion 1a, the shoulder 3a of the external lead is molded while holding the curved shoulder 3a of the external lead as in the conventional example.
Due to the springback of a, the external leads 2 at both ends do not return to their warped state, as shown in Fig. 6(C).
As shown in the figure, the tips 3c of the external leads 2 are aligned on the same line. Specifically, when the resin body has a warpage of 50 μm, the warp of the tip of the external lead is 70 μm or more in the conventional example, whereas in this embodiment, the warp can be reduced to 20 μm or less.

FIG. 2 is a side view of an IC showing a second embodiment according to the present invention. In this embodiment, the resin protrusion 1a of the first embodiment continuously covers the portion corresponding to the shoulder portion 3a of the external lead from the resin body 1, whereas the resin protrusion 1a and the resin body 1 are separated. The upper and lower surfaces of the shoulder portion 3a of the external lead are partially exposed. However, the resin protrusion 1a and the resin body 1 are connected at both ends. In this embodiment, when the external lead held by the resin protrusion 1a is bent, even if microcracks occur at the interface between the resin protrusion 1a and the external lead, the resin protrusion 1a
Since they are separated from the resin body 1, there is an advantage that there is no possibility of moisture resistance deterioration.

〔Effect of the invention〕

As explained above, in the IC of the present invention, the portion corresponding to the shoulder of the external lead, which conventionally extends from the side surface of the resin body parallel to the mounting surface, is covered and fixed by the resin protrusion.
When molding the external lead, the resin protrusion is held lightly between the pressing surfaces of the bat and the die to the extent that no deformation occurs, and the external lead is bent from the resin protrusion and its tip is bent back. The tip of the external lead is not affected by the springback caused by molding while holding the shoulders of the external lead in a warped state. Therefore, the tips of the external leads remain bent and shaped, and there is an effect that the tips of the external leads can be aligned on the same plane.

[Brief explanation of drawings]

FIG. 1 is a side view of an IC showing a first embodiment of the present invention, FIG. 2 is a side view of an IC showing a second embodiment of the present invention, and FIG. 3 is a side view of an IC showing a second embodiment of the present invention. 4 is a side view showing a conventional IC, and FIGS. 5(a) and 5(b) are an example of a mold for shaping the external leads of a conventional IC. Sectional view and its CC sectional view, No. 6
Figures (a), (b), and (C) are side views of each IC after resin sealing and after bending the external leads. 1... Resin body, 1a... Resin protrusion, 2, 2a...
External lead, 3a...shoulder part, 3b...middle part, 3C
...Tip, 4a...Side, 4b...Mounting surface, 5...Die, 6...Butt, 7...Punch, 8
...Press surface, 9...Prevention surface, 10a, 10b-...
Hollow.

Claims (1)

[Claims] A resin body containing a semiconductor chip has a plurality of external leads protruding outward on a side surface thereof, and the external leads have a shoulder extending parallel to a mounting surface of the resin body and a shoulder extending downward from the shoulder. protruding from the middle part and the mounting surface;
In a resin-sealed semiconductor device configured with a tip bent downward from the intermediate portion so as to be substantially parallel to the mounting surface, a shoulder of the external lead extends parallel to the mounting surface from a side surface of the resin body. A boundary part between the part and the intermediate part is covered and fixed with resin, and the intermediate part has an external lead bent downward from the edge of the resin that covers and fixes the shoulder part of the external lead. A resin-sealed semiconductor device characterized by: