JPS6240851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin-sealing mold for a semiconductor device.

In the case of semiconductor devices, the semiconductor element is die-bonded onto the lead frame, and the lead frame and the semiconductor element are wire-bonded, and then
In order to protect these semiconductor elements from external physical and mechanical pressure, means for sealing them with resin is generally used.

A conventional resin sealing mold for performing this type of resin sealing will now be described with reference to FIGS. 1 and 2.
In each of these figures, numerals 1 and 2 are a pair of lower and upper surface plates, 3 is a post that guides each of these surface plates in the vertical direction, and 4 and 5 are attached to the opposing surfaces of each surface plate. These are the lower mold and the upper mold that make up the mold. The lower die 4 has a runner 7 extending around the pot 6, and each runner is provided with a lower die cavity 9 via a gate 8.
Further, the upper mold 5 is provided with an upper mold cavity 10 corresponding to the lower mold cavity.

In this configuration, after the semiconductor device 11 to be molded is sandwiched between the lower mold 4 and the upper mold 5 including the cavities 9 and 10 and the molds are matched, a plunger (not shown) is applied. The molten resin supplied under pressure is squeezed by the gate 8 from the pot 6 and the runner 7, and is filled between the cavities 9 and 10, thereby achieving the desired resin sealing.

However, as is well known, this conventional configuration has a major drawback in that air is trapped in the resin-sealed portion. In other words, filling the runner 7, gate 8, and cavities 9 and 10 with the molten resin described above is nothing but replacing the air existing in these parts with the resin, and at this time, the air is not drawn into the resin. occurs frequently, and various reasons can be assumed, but
In any case, it is a problem that is difficult to solve as long as air exists in each of the parts. Regardless of the type of semiconductor device being encapsulated, this air entrainment has a negative impact on the performance of the device in terms of moisture resistance, weather resistance, impact resistance, etc., and may cause other molding problems. This is a major drawback, for example, non-injection, burr generation, etc.

In view of these drawbacks of conventional resin sealing molds, this invention prevents air from being entrained during sealing by making it possible to remove the air present inside while filling with molten resin.

Hereinafter, one embodiment of the resin-sealed mold according to the present invention will be described in detail with reference to FIGS. 3 to 8.

In these Figures 3 to 8, the first
The same reference numerals as in the figures and FIG. 2 indicate the same or corresponding parts, and 12 is an air bend connected to each of the lower mold cavities 9, 13 is a pressure reducing groove that guides each of these air bends to the pressure reducing hole 14, and 15 is a pressure reducing groove shown in the above. Dummy cavities provided at each end of the runner 7; 16, a vacuum hole connected to each dummy cavity; 17, 18, conduits connecting each vacuum hole 14, 16 to an external vacuum pump, etc.; 19, a vacuum hole 16; It is an operating pin that is assembled into a pressure reduction on-off valve and has a notch 19a that serves as a passage.It is operated and controlled by a cylinder 20 supported by a support frame 21 and is moved up and down as shown by arrows A and B to open and close the valve. Furthermore, seal grooves 22 are formed on the four surfaces of the lower mold surrounding these parts, and seals 23 are disposed thereon so as to be able to seal with the five surfaces of the upper mold.

Therefore, in the configuration of this embodiment, after the semiconductor device 11 is sandwiched between the lower mold 4 and the upper mold 5 and the molds are aligned as in the conventional case, the operating pin 19 is first raised in the direction A to open the pressure reducing valve. The pressure inside the mold is reduced through the respective pressure reduction holes 14 and 16. At this time, the pressure reducing hole 14 mainly reduces the pressure in the cavities 9 and 10 from the air bend 12, and the pressure reducing hole 16 mainly reduces the pressure in the runner 7, the pot 6 connected thereto, and the gate 8.

Then, in this reduced pressure state, molten resin is introduced under pressure from the pot 6, but at this time, the timing is such that the cylinder 20 lowers the operating pin 19 in the direction B to close the pressure reducing valve. As a result of this operation, the flow of the molten resin that has flowed into the dummy cavity 15 from the runner 7 is temporarily stopped, and
This dummy cavity 15 functions to confine the air in that area, and does not leak out from the decompression hole 16 to the outside. At this time as well, the pressure inside the cavities 9 and 10 continues to be reduced through the pressure reduction hole 14, and then from the gate 8 into each cavity 9 and 10.
Molten resin is introduced into the air bend 12 for sealing, and in this case, by selecting the depth of the air bend 12, it is possible to prevent the resin from flowing out to the air bend 12 side. Here, the depth of the air bend 12 is 0.03 to 0.05 when the sealing resin is silicon.
mm, and in the case of epoxy, 0.02 to 0.025 mm, good sealing molding is possible. Also, lower mold 4, upper mold 5
The seal 23 in between can further enhance the above effect by preventing air from entering the mold as much as possible during this vacuum molding.

As described in detail above, according to the structure of the present invention, since the resin sealing of the semiconductor device using the mold is performed by vacuum molding, the entrainment of air during resin sealing is eliminated and good sealing is achieved. Since molding becomes possible, the performance and reliability of resin-sealed semiconductor devices can be improved, and productivity can also be improved. In addition, a pressure-reducing on-off valve is installed in a part of the pot or runner that makes up the mold, and its opening and closing is controlled in synchronization with the pressurized introduction of molten resin, so that the cavity is filled with the flow of resin temporarily stopped. During this time, the reduced pressure inside the cavity is maintained, so that air can be reliably prevented from getting into the resin-sealed part.
Together with the sealing action between the lower mold and the upper mold, the above-mentioned effect can be fully supported.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and a plan view of a lower mold of a conventional resin-sealed mold, and FIGS. 3 and 4 are cross-sectional views showing an embodiment of a resin-sealed mold according to the present invention. Figures 5 and 6 are sectional views of the depressurizing section, respectively, Figure 7 is a sectional view of the operating pin, and Figure 8 is a sectional view showing the operating state of the configuration shown in Figure 6. It is. 4...Lower mold, 5...Upper mold, 6...Pot, 7...
...Runner, 8...Gate, 9,10...Lower die,
Upper mold cavity, 11... semiconductor device, 12...
Air bend, 13... pressure reducing groove, 14, 16... pressure reducing hole, 15... dummy cavity, 19... actuation pin (pressure reducing opening/closing valve), 22... seal.

Claims (1)

[Claims] 1. A pot consisting of a lower mold and an upper mold that can be matched, and into which molten resin is introduced under pressure between the two molds;
A mold having a runner connected to the pot and a cavity connected to the runner through a gate, the mold comprising a pressure reducing on-off valve connected to the runner and the pot through a dummy cavity, and a seal surrounding the outer periphery of each of these parts. , when sealing with resin, a pressure reduction on-off valve is controlled to close in synchronization with the introduction of molten resin on the dummy cavity side, so that air in the mold can be sucked in a short time. Resin sealing mold for semiconductor devices.