JPS60101018A - Mold for resin sealing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of Isu J] The present invention relates to the structure of a mold suitable for resin-sealing a semiconductor (hereinafter referred to as a resin mold). It relates to the resin flow path structure inside the mold for molding resin-molded semiconductors with high yield.

[Background of the invention]

A concrete example of a thermosetting sealing mold used to mold a large number of resin mold semiconductors (hereinafter referred to as "products") per shot is Patent P1O2SSS6 (Special Publications). 55-17697). This, t7 will be explained with reference to FIGS. 1 and 2.

FIG. 1(a) is a sectional view taken along line I-1 of FIG. 1(b) (a plan view of the mold viewed from the dividing surface in the horizontal direction). FIG. Bo,t (
or sprue) 1 and the molten resin is pressurized by runner 2.
．． Touch the gate 5 to find the cavity 6 in which the insert (for example, a lead frame such as a semiconductor insert) is set.
After the resin has hardened, the mold is released and the 5 gates are folded to obtain the desired product.

As is clear from the figure, the height h formed by the bottom wall to which the gate 5 of the runner 2 is not connected and the soil wall is in the shape of a bar, and the runner rises in the direction of movement of the molten resin 7. The cross-sectional area of 2 is decreasing linearly. Also, Fig. 1(c)
The longitudinal cross-sectional views of each cage 5 branching from the crawler 2 are A-A, B-B, C-C, and D near the bot 1.
-D.

It is shown as E-41:. As is clear from the figure, the angle θ of the gate 5 (the angle formed by the upper and lower surfaces of the gate) gradually increases as the cavity 6 is farther away from the boat 1.

In other words, to〈θ8kuΦ〈θゎkuθ8・・・・・・・・・・・・
...(1) With this configuration, the flow velocity of the bath melt in the runner 2 → the resin 7 changes as the runner 2 cross-sectional area changes in the flow direction of the resin as it moves away from the holt 1. It is faster than that in the case of V.

On the other hand, when the constriction angle θ of the gate 5 increases, the pressure loss of the molten resin passing through it decreases, so by increasing the constriction angle θ of the gate 5 as the distance from the bot 1 increases, The total pressure loss of the molten resin 7 up to 6 (=pressure loss when passing through the lunch + pressure loss when passing through the gate) can be made equal. If the pressure losses are equal, the flow velocity of the molten resin 7 in each cavity will also be equal.

Figures 2(a) and 2(b) show how resin is filled in each cavity in the conventional mold. In Fig. 2(a), the horizontal axis is the dimensionless time ni from the start of resin filling in the cavity.
l T / To (T is the time from the start of resin filling into the cavity, To is the time until the cavity is finished filling with resin), and the vertical axis is the resin filling rate W / Wo ( W is resin filling Is at time T,
Wo is the resin filling M) at the time To, and each scale is 47. While the resin is being filled into each cavity, the slope shown in the figure, that is, the resin flow rate is the same, but
The cavity closer to bot 1 is 41! -I Since the fat filling start time is earlier, the filling completion time is also earlier.

Therefore, after the cavity on the upstream side is filled, the resin flow rate flowing therein shifts to the cavity on the 111th downstream side, so that the farther the cavity is from the bot 1, the higher the resin flow rate is before the filling is completed. For this reason, there is a problem in that the farther downstream the cavity is, the greater the force is applied to the insert, making it more likely to deform. In addition, since filling is completed first in the upstream cavity, the flow of resin at the gate part stops and the gate seal, where the resin hardens due to the heat transfer effect of the mold, progresses, and the final pressure of the resin is not sufficiently applied to the cavity. In other words, there were cases where the molded product was completed without the voids being completely crushed. therefore,
In order to avoid these problems, it is necessary to synchronize the resin filling completion time in each cavity.
If the above-mentioned conventional mold structure remains unchanged, as shown in FIG. Figure (e)
However, the former has the disadvantage that the molded product cannot be broken from the base during gate breaking (removal of broken gate resin) after product molding, and the latter has the disadvantage that it cannot be broken from the base of the molded product. There was a problem that the bottom of the gate 5 was deeper than the bottom 2, making it difficult to process the mold. Therefore, in the conventional mold structure, it was not possible to synchronize the resin filling completion time in each cavity, and it was not possible to improve the reliability and yield of the product η.

[Purpose of the invention]

It is an object of the present invention to eliminate the drawbacks of the conventional molds for resin molding semiconductors, etc., as described above, eliminate problems caused by uneven filling completion times of resin in each cavity of the mold, and achieve uniform quality and reliability. To provide a resin molding die capable of molding high quality products with good yield.

[Summary of the invention]

The present invention relates to a mold for a resin mold.

An air vent section is provided at the end of each cavity for obtaining the product, and the specifications (width or depth) of the air vent section for each cavity are gradually widened as the distance from the bot increases, that is, in the direction of resin flow. The resin flow from the bottom to the bottom by increasing the size in order to reduce the flow resistance! 10 The internal structure of the mold absorbs time differences due to differences in starting points, easily aligning the resin filling completion times in each cavity, and making the final pressure of the molten resin applied to each cavity constant. The remaining voids due to the gate seal caused by uneven resin filling completion times, poor resin adhesion to the insert, and deformation of the insert due to increased flow velocity (increased pressure loss) in the downstream cavity. It can be prevented.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. In the figure, the same numbers as in FIG. 1 are the same parts. FIG. 6(a) is a plan view of the mold viewed from the dividing plane in the horizontal direction, and an air vent 8 is arranged at the end of the cavity 6 from which the product is obtained. Also, single 5 figures (b
) are each gate 5.) branching from runner 2. Cavity 6,
The vertical cross-sectional views of the air vent 8 are A'-N, B'-B', C'-C' in order from the bot 1, 1)
'-D' and g-bi are shown. As is clear from the figure, the aperture angle θ of the gate 5 and the air vent 8
The depth h/ of the cavity 6 becomes larger as the cavity 6 is farther away from the bot 1.

That is, θ,〈 θ8〈 θ. 〈θ〉θ8・・・・・・・・・
・・・・・・・・・ (suhλ〈h4〈11′c＜h et al.
h6・・・・・・・・・・・・・・・(2) Note that in this embodiment, the widthwise dimension W of the air vent 8 is fixed constant, and its depth h′ is determined in the resin flow direction. However, the same result can also be obtained by fixing the depth h' of the air vent 8 and gradually increasing its width W toward the downstream side. Furthermore, both h' and W may be increased sequentially toward the downstream side.

FIG. 3(a) also shows the state of resin filling in each cavity. Since the filling of the molten resin starts from the cavity 6 near the pot 1, filling is completed first in the cavity 6 near the bot 1 due to this time difference, but there is an air vent 8 at the end of the cavity 6. Since the resin is attached to the air vent 8, the resin further flows toward the air vent 8. This situation also occurs in the cavity 6 on the downstream side, and by appropriately determining the depth h', s or width W of the air vent 8 for each cavity and adjusting its volume, each air vent 8 can be finally The resin flow stop times in the cavity match. In this case, the air vent 8 satisfies the original function of gas escape, and provides lubrication and wear resistance to the mold surface to prevent it from becoming clogged with the residue of molding additives, mold release agent, etc. Since it is set after being treated with a fluorinated carbon resin such as a tetrafluoroethylene resin that has excellent properties and mold release properties, there are no problems in practice.

In this example, the air vent part was determined based on the results of a simulation in a fluid state, and the specifications of the air vent were made thicker as the distance from the bot 1 increased.
Since the flow resistance of the 4!1 resin is made small, it is possible to absorb the time difference due to the difference in the flow starting point from the void 1, and it is possible to easily synchronize the resin filling completion times in each cavity 6.

A comparison of the filling situation between a conventional mold and a mold according to the present invention is shown in FIGS. 4(a) to 4(C). Note that the actual record (-) indicates the resin filling situation in the mold according to the present invention, and the broken line indicates the resin filling situation in the conventional mold. From this, it can be seen that in the present invention, the filling completion times are the same for all cavities. According to the flow simulation results, if there is a difference in the filling completion time of each cavity as in the past, the number of flow paths decreases by one each time the upstream cavity is filled, and the pressure loss (flow rate) decreases in LRISil. It was found that the resistance (resistance) increases.

On the other hand, it has been found that when all the cavities have the same filling completion time as in the present invention, the instantaneous increase in pressure loss does not occur and the pressure loss becomes extremely small.

FIG. 5 shows a comparison of the curve p angles of the gold wires inserted into each cavity. In conventional molds, each time the cavity on the upstream side is filled, the flow of resin that was flowing in that part is added to the downstream side, increasing the flow velocity in the cavity, so that it is poured into the cavity. There was a problem in that the bending of the gold wire was increasing, and especially in the cavity from the launch to the end, the gold wire surface cine defects often occurred. In the mold according to the present invention, the above phenomenon does not occur, and the bending point of the gold wire is kept at a small value in any cavity.

Figure 6 shows a comparison of the state of void occurrence. In conventional molds, the filling of the cavities near the top and bottom is completed first, and the resin stays in the gate area and the curing reaction progresses due to the heat transfer effect of the mold, so the gate area is fully filled within the sealing groove. However, in the mold according to the present invention, there is no such problem, and the occurrence of voids is extremely reduced.

In the above embodiments, a mold for sealing with a thermosetting resin was described, but the present invention can be similarly applied to a mold for sealing with a thermoplastic resin or the like.

〔Effect of the invention〕

As explained in detail above, in the mold according to the present invention, an air vent part is provided at the end of each cavity for obtaining a product, and the width or depth of the air vent part for each cavity is gradually adjusted in the direction of resin flow. By reducing the flow resistance and absorbing the time difference caused by the difference in the starting point of resin flow from the pot, the final pressure of the bath melted resin applied to each cavity is adjusted by aligning the resin filling completion time at each = V - cavity. Since the internal structure of the mold is made to be constant, this can be achieved by reducing the remaining voids due to uneven resin filling completion times and the failure of resin adhesion to the insert. In addition, deformation of the insert due to increased resin flow velocity (increased pressure loss) in the downstream cavity can be prevented, and unreliable products with uniform quality can be easily molded with high yield.The practical effect is extremely large. .

[Brief explanation of the drawing]

Figure 1 shows a conventional mold, (a) is a 1-1 sectional view of (b), (b) is a plan view of the mold seen from the dividing plane in the horizontal direction, and (C) is (b). A-A, B-B, C-C,
D-D, E-E sectional views, (d) (e) Cross-sectional view showing the next mold borrowing necessary to align the resin filling completion time in each cavity in B-1, 2nd (a) is a graph showing the resin filling situation in each cavity in a conventional mold, and (b) is a graph showing the cavity number of the conventional mold. Figure 3 is an embodiment of the present invention, (a) is a plan view of the mold viewed from the dividing plane in the horizontal direction, (b) is -N, B'-B of (a). ', C'-C', l)'-
ff, r-Iff sectional view, and FIG. 4(a) is a comparison graph of the resin filling situation in each cavity between the mold of the present invention and the conventional mold, and FIG. 4(b) and (e) are Well, #1
Part 1'1 A diagram showing the cavity numbers of the mold according to the present invention and the conventional mold, Figure 5 is a comparison graph of the metal wire surface area between the mold of the present invention and the conventional mold, and Figure 6 ( Fig. 6(b) and (C) are graphs comparing the state of void generation between the mold according to the present invention and the conventional mold, and Fig. 6(b) and (C) are graphs showing the cavity No. 4 of the conventional mold and the mold according to the present invention. FIG. 1... Pot, 2... Lunch, 5... Gate, 8... Air vent, h'...
Air vent depth, W...Air vent width, θ...Gate aperture angle. 1st mouth Figure 2 (l12) Juseikofun do @tsu・δtsu, I! Next 11 rooms (shi) Figure 3 (a) (b) A'-A'B'-8'C'-C'D'-D'E'
-Doth 4z 0 0, I Q, 203 Q4θSθ60.7 Q8
0.9 4M face mask M@ka 5 cheek dimension shield (±)

Claims (1)

[Scope of Claims] 1. In a mold for resin sealing, in which a number of cavities are arranged along the runner, which are branch-connected via gates to a runner connected to a port, a soto, or a sprue, the product can be sealed. For resin sealing, an air vent is provided at the end of the cavity to be obtained, and its volume is gradually increased as it moves away from the bow, so that the resin filling completion time in each cavity is aligned. Mold. 2. Patent 11II, which is characterized in that the cross-sectional area of the runner is gradually decreased as the distance from the pot increases, and the aperture angle of the gate is gradually increased. Mold for resin sealing in item 1 of the bud range.