JPH09219413A - Mold for encapsulating semiconductor device with resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a load, which is applied to outer lead parts, heavier than a prescribed weight and to contrive to make uniform the distribution of the pressure, which is exerted on the parts, by a method wherein dummy force-cutting surfaces are provided on the side of the smaller pressing area between the pressing area on a gate side and the pressing area on the opposite side to the gate side in such a way that the pressing area on the gate side and the pressing area on the opposite side to the gate side are made equal to each other. SOLUTION: A gate part force-cutting surface 6 prevents a resin from flowing out from an encapsulating resin flow path to the surface and rear of a lead frame. The width of the surface 6 is formed into a width of 0.3mm and is made narrower than that of the gate part force-cutting surface of a resin sealing metal mold of a conventional structure. A runner part force-cutting surface 7 is one which prevents a resin, which flows out on the side surfaces of the lead frame, from leaking out to the surface and rear of the lead frame. The total pressing area of the surfaces 6 and 7 is assumed (a). Then, the width W2 of force-cutting surfaces 8 on the opposite side to a gate side is similarly formed into a width of 0.3mm and the pressing area of the surface 8 at that time is assumed (b). In this case, the difference between the pressure areas becomes a>b, but dummy force-cutting surfaces 9 having an area of a-b equal to the difference between the (a) and the (b) are additionally arranged. In such a way, the total pressing area (a) on the gate side is made as small as possible by the force-cutting surfaces other than outer lead part force-cutting surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin encapsulating mold for a semiconductor element, and more particularly to a resin encapsulating mold for a semiconductor device which is encapsulated with a synthetic resin such as a thermosetting resin.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a state in which a conventional semiconductor element is sealed with a resin. FIG. 3 schematically shows an arrangement of push-cut surfaces of a resin mold. The lead frame 1 on which the semiconductor element is mounted is arranged between the upper and lower molds 4a and 4b forming the mold 4, and is clamped by the upper and lower molds. After completion of the mold clamping, the sealing resin is put into the mold 4 and filled in the cavity 3 through the gate 2.
In addition, the upper and lower molds 4a, 4 located at the outer edge of the cavity 3
b is provided with a push-cut surface 5, a load is applied to the push-cut surface 5 at the time of mold clamping, and the lead frame 1 is slightly crushed, so that the resin flows out to the outer lead when the resin is filled, that is, Prevents the generation of resin burr.

[0003]

FIG. 4 shows a state in which a conventional resin-sealed mold for a semiconductor element is clamped. It is the outer lead portion push-cut surface 5, the gate portion push-cut surface 6, the runner portion push-cut surface 7, and the non-gate side push-cut surface 8 that receive the load during mold clamping, but it is important in preventing the occurrence of resin burr. Is a portion of the outer lead push-cut surface 5.

In the conventional structure, with respect to the area of the outer lead portion push-cut surface 5, the other portion of the push-cut surface 6,
The total area of 7 and 8 is large. That is, the width of the gate pushing surface 6 is usually about 1 to 2 mm, and the width of the runner pushing surface 7 is as small as about 0.5 mm, but the length extends over the entire length of the frame.
The total area of 8 is large. Therefore, the mold clamping pressure applied to the outer lead pressing surface 5 is not sufficient,
Resin burr may occur.

Further, comparing the pressure areas other than the outer lead pressing surface on the gate side and the non-gate side of the package, the area of the gate pressing surface and the runner pressing surface is large as described above. The side is getting bigger. Therefore, the pressure distribution in the mold during mold clamping becomes non-uniform. As a result, the pressure applied to the outer lead pressing surface 5 becomes non-uniform, and resin burrs may occur on the gate side where the pressure becomes low. Further, if the mold is clamped at a pressure higher than necessary on the side opposite to the gate where the pressure is increased, the outer lead may be crushed to have a large amount and the strength may be reduced, and lead breakage or the like may occur.

[0006] FIG. 5 shows the result of measuring the crush amount (plastic deformation amount) on the push-cut surface of the outer lead by actually performing mold clamping with a resin sealing mold. Using a resin-sealed mold with four frames, the crush amount on the gate side and the crush amount on the anti-gate side of the outer lead portion are shown in units of μm for each position in the mold. It can be seen from FIG. 4 that the amount of collapse on the gate side is clearly smaller than that on the side opposite to the gate. The area ratio of the pressing surface in this case is 2.06 on the gate side other than the outer lead section and 0.30 on the non-gate side when the outer lead section is 1.00, and the pressing area on the gate side becomes extremely large. In the outer lead part, resin burr is generated only on the gate side.

In view of the above problems, the present invention makes a load applied to an outer lead portion of a lead frame in a resin-sealed mold for a semiconductor element a predetermined magnitude or more at the time of mold clamping, and a pressure distribution in the corresponding portion. The purpose is to prevent the occurrence of resin burrs and the reduction of the strength of the outer leads by keeping the temperature uniform.

[0008]

In a resin-sealed mold used for resin-sealing a semiconductor element mounted on a lead frame, a portion to be pressed by die clamping is used as an outer lead portion and other portions. Separately, arrange so that the pressure area other than the outer lead portion is equal on the gate side and the non-gate side of the package, and the total pressure area other than the outer lead portion is less than the total pressure area of the outer lead portion. Make a structure. On the push-cut surface other than the outer lead portion, a dummy push-cut surface is provided in the smaller area so that the pressure areas on the gate side and the non-gate side are equalized.

[0009]

FIG. 1 shows an embodiment of the present invention.
The gate push-out surface 6 prevents the resin from flowing out of the flow path of the sealing resin to the front and back surfaces of the lead frame.
Its width is 0.3 mm, which is smaller than that of the conventional structure. The runner portion push-cut surface 7 prevents the resin flowing out to the side surface of the lead frame from leaking to the front and back surfaces of the lead frame. In this embodiment, the runner portion push-cut surface is intermittently arranged, and the length L thereof is set to 5 mm in consideration of the resin flow distance on the side surface of the lead frame, which is usually about several mm. Also, like the push-cut surface 6, its width W1 is 0.3 m.
m. The total pressing area of the push-cut surfaces 6 and 7 arranged in this way is defined as a.

Next, the width W2 of the non-gate side push-cut surface 8 is similarly set to 0.3 mm, and the pressing area at that time is set to b.
In this case, the pressing area is a> b, but a dummy push-cut surface 9 having an ab area corresponding to the difference is newly arranged.

In this way, in the push-cut surface other than the outer lead portion, the total pressure area a on the gate side is made as small as possible, and the total pressure area on the non-gate side is also set as a, and the push-cut surface other than the outer lead portion is set. 2 of total pressure area
a is made smaller than the sum of the pressing areas of the outer lead pressing surface.

Further, typical values of the width and the length of each push-cut surface will be described below. The width of the push-cut surface of the runner is 0.2 mm to 0.5 mm, and the length is 5 m.
m to 20 mm. The width of the push-cut surface of the gate portion is 0.2 mm to 0.5 mm, and the length is determined by the size of the lead frame and the package. Further, the width of the push-cut surface on the side opposite to the gate is 0.2 mm or more, and there is no particular limitation on the maximum value.

Further, the dummy push-cut surface may be provided not only on the side opposite to the gate but also on the gate side. The above contents are applied to types such as DIP and SOP which have outer leads only on two sides facing each other in the package, but in the case of the QFP type which has outer leads on all four sides of the package,
Since there is no anti-gate-side push-cut surface, the total pressure area of the dummy push-cut surface 9 arranged on the anti-gate side is set to a.

[0014]

As described above in detail, according to the present invention, the push-cut area of the outer lead portion is larger than the sum of the push-cut areas other than that, and the push-cut surface other than the outer lead portion is opposite to the gate side. Since the areas on the gate side are the same, it is possible to effectively and well balance the pressure applied to the outer lead portion during mold clamping. Therefore, it is possible to prevent the occurrence of resin burrs in the outer lead portion and suppress the reduction in the yield of resin-sealed products.

Further, the step of removing the resin burr after the sealing step can be omitted and the number of steps can be reduced. In addition, since local concentration of the load can be avoided, the outer leads are not crushed more than necessary, and the reduction in the strength of the leads hardly occurs. Further, since the total pressing area at the time of mold clamping becomes small, it is possible to reduce the size and weight of the resin sealing device for performing mold clamping.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an arrangement of push-cut surfaces in a resin-sealed mold of the present invention.

FIG. 2 is a view showing a state in which a lead frame is set in a conventional resin-sealed mold and then the mold is clamped.

FIG. 3 is a diagram showing an arrangement of push-cut surfaces of a conventional resin-sealing mold.

FIG. 4 is a view showing an arrangement of push-cut surfaces of a conventional resin-sealed mold.

FIG. 5 is a diagram showing the result of measuring the amount of crushing on the push-cut surface of the outer lead by clamping the lead frame with a conventional four-frame taking resin-sealed mold, for each position in the mold.

[Explanation of symbols]

1 ... Lead frame, 2 ... Gate, 3 ... Cavity, 4 ... Push face, 5 ... Outer lead push face, 6 ... Gate push face, 7 ... Runner push face, 8 ... Anti-gate push face, 9 ... Push-cut surface of dummy, 10 ... Outer lead of lead frame (or semiconductor package), 11 ... Runner.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B29L 31:34

Claims (6)

[Claims] 1. A resin encapsulation mold for encapsulating a semiconductor element mounted on a lead frame with a resin, wherein a total area of a push-cut surface other than the outer lead portion of the lead frame is equal to an outer lead portion. If the dummy push-cut surface is smaller than the area of the push-cut surface that is placed and the push-cut surface other than the outer lead part has the same total area of the gate-side push-cut surface and the opposite gate-side push-cut surface. A resin-sealed mold for a semiconductor element, which is provided. 2. The resin-sealed mold for a semiconductor element according to claim 1, wherein the dummy push-cut surface is provided on the side opposite to the gate. 3. The resin encapsulation mold for a semiconductor element according to claim 1, wherein a runner portion push-cut surface, which is one of the push-cut surfaces other than the outer lead portion, is separated along the runner. . 4. The resin encapsulation mold for a semiconductor element according to claim 3, wherein the runner portion push-cut surface is installed with a length longer than a flow distance of the resin. 5. A first push-cut surface arranged on a gate portion communicating with a cavity for accommodating a semiconductor element mounted on a lead frame, and arranged along a runner portion communicating with the gate portion. A second push-cut surface, a third push-cut surface arranged along an edge of the cavity on the side opposite to the gate, and a third push-cut surface disposed near the side of the cavity opposite to the gate.
A dummy push-cut surface having an area such that the sum of the area of the push-cut surface of the lead frame is equal to the sum of the area of the first push-cut surface and the second push-cut surface, and the outer lead of the lead frame is arranged. A push face having a larger area than the sum of the total areas of the first push face, the second push face, the third push face and the dummy push face arranged along the edge of the cavity. A resin-sealed mold for a semiconductor device, comprising: 6. The width of the push-cut surface of the gate portion is 0.
2 mm to 0.5 mm, the width of the push-cut surface of the runner portion is 0.2 mm to 0.5 mm, the length is 5 mm to 20 mm, and the width of the push-cut surface on the side opposite to the gate is 0. The resin-molded mold for a semiconductor device according to claim 5, wherein the mold is 0.2 mm or more.