JPH0729327B2 - Transfer molding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transfer molding method, and particularly to a transfer molding method suitable for manufacturing a precision resin molded body related to microelectronics such as a resin-sealed semiconductor device. Regarding the method.

[Prior Art] Conventionally, as a method of molding a resin molded body, a thermosetting resin is heated and pressed to be pressed into a resin molded body cavity (hereinafter, referred to as a cavity) from a resin injection portion (hereinafter, referred to as a gate), A transfer molding method for molding is known.

3 (a) and 3 (b) are views showing a resin molding method by a transfer molding method, wherein FIG. 3 (a) is a plan sectional view and FIG. 3 (b) is FIG. 3 (a). FIG. 3 is a sectional view taken along line III-III of FIG.

The mold is provided with a center cull 4, and a plurality of runners 1 passing through the center cull 4 are branched. Each runner 1 communicates with a plurality of cavities 3 via a gate 2. Inside each cavity 3, a semiconductor integrated circuit element 6 serving as a resin seal is arranged. The semiconductor integrated circuit element 6 is fixed on the lead frame 7, and the terminals of the lead frame 7 and the electrodes of the semiconductor element 6 are connected by the bonding wires 5. The lead frame 7 is held between the upper die 10 and the lower die 11 of the die.

In the mold configured as described above, the heated and pressurized resin 8 is supplied from the center cal 4 to the runner 1,
It flows through the runner 1 and is injected into the cavity 3 through the gate 2. In each cavity 3, after the resin 8 is filled, it is cooled by the molds 10 and 11 and solidified to obtain a resin molded body.

In the conventional transfer molding method, the resin 8 is sequentially injected and filled from the cavity 3 near the center cal 4, and finally the resin 8 is injected and filled into the cavity 3a farthest from the center cal 4. The injection is complete.

[Problems to be Solved by the Invention] However, the conventional transfer molding method described above has the following drawbacks.

First, the viscosity of the resin 8 when the resin 8 is injected into the cavity 3 close to the center cal 4 in the first half of the molding process, and the resin 8 is injected into the cavity 3a distant from the center cal 4 in the latter half of the molding process. Resin of time 8
Of the resin 8 differs depending on the temperature drop of the resin 8 during that time.
Therefore, the cavity 3a located far from the center cull 4
The resin 8 may have already begun to harden when the resin 8 is injected into. Then, the hardened resin is pressed into the cavity 3a and deforms the bonding wire 5.

Further, when the resin 8 is injected and filled in the cavity 3a farthest from the center cull 4, the other cavity 3
The resin 8 has already been substantially filled therein. As a result, since the injection pressure is intensively applied to the cavity 3a, the injection speed of the resin 8 is inevitably increased, which may deform the bonding wire 5, and also the appearance of the molding resin. Adversely affect.

Thus, in the conventional molding method, the cavity 3
Since the runner 1 has different lengths due to the difference in the arrangement position of the resin, there is a drawback that the behavior and characteristics of the resin 8 are different for each cavity.

The present invention has been made in view of such problems,
Avoid injection delay of resin to specific cavity,
It is an object of the present invention to provide a transfer molding method capable of preventing a deformation of a bonding wire, stabilizing a resin appearance, and obtaining a molded body having improved quality and reliability.

[Means for Solving Problems] The transfer molding method according to the present invention is a transfer molding method in which a thermosetting resin that has been heated and pressed is press-fitted into each cavity from a runner through a plurality of injection parts. In the molding method, an opening / closing means is provided in the injection part, and after the resin is supplied to a predetermined number of injection parts, the opening / closing means is opened to inject the resin into each cavity simultaneously from the runner.

[Operation] In the present invention, first, the opening / closing means is closed to shut off the injection part, and the resin sent through the runner is supplied to a predetermined number of injection parts (for example, all the parts connected to the runner). After being supplied to all of the injection parts, the opening / closing means of each injection part is opened simultaneously.

Then, the resin is simultaneously and progressively injected into the respective cavities from the runner to which they are connected. As a result, for example, a situation where the injected resin is cured only in the innermost cavity is avoided, and a uniform resin is supplied to each cavity. Further, since the resin is simultaneously supplied to each cavity, the injection pressure is uniform. Therefore, the deformation of the bonding wire is prevented, and a high quality resin molded body can be obtained.

[Embodiment] FIGS. 1 (a) and (b) and FIGS. 2 (a) and (b) are views showing an embodiment of the present invention, and FIGS. 1 (a) and 1 (b) are cavities. FIGS. 2A and 2B are a plan view and a cross-sectional view showing a state before the resin is injected, and FIGS. 2A and 2B are a plan view and a cross-sectional view showing the state after the injection. The mold used in this embodiment is composed of an upper mold 12 and a lower mold 13. And by overlapping this upper mold 12 and lower mold 13,
From the recesses formed in the upper mold 12 and the lower mold 13, a runner 14, a cavity 15, etc. are formed as shown in each drawing.

The runner 14 is branched from a center curl (not shown), and five resin injection portions (hereinafter, referred to as gates) 16 extend on both sides of the runner 14. And
The gate 16 is connected to each of a plurality of cavities 15 arranged in the longitudinal direction of the runner 14. Therefore, the cavity 15
Are each connected to the runner 14 via a gate 16.

A shield plate 17 for opening and closing each gate 16 is attached to the lower mold 13. The shielding plate 17 is arranged for each gate 16 such that its surface is orthogonal to the resin flow direction of the gate 16, and can be moved up and down as shown by an arrow 18. Then, the shielding plate 17 advances to the position of the upper end and extends to the gate 16
Closed, retracted downward and opened the gate 16. The plurality of gates 16 are connected to each other and are simultaneously opened or closed.

The resin 8 arrives at the tip of the runner 14, and the runner 14 is the resin 8.
A sensor (not shown) for detecting the filling is attached. The detection signal of this sensor is input to the control device (not shown). When the control device inputs the detection signal from the sensor, the control device lowers the shield plate 17 to lower the gate 16
Open.

A semiconductor integrated circuit device 6 is mounted on the lead frame 7, and the electrodes of the device 6 and the terminals of the lead frame 7 are connected by bonding wires 5.

First, the lead frame 7 that has completed the bonding work
Are clamped between the upper mold 12 and the lower mold 13, which are superposed on each other. Then, the shielding plate 17 is lifted to close the gate 16 to disconnect the cavity 15 and the runner 14 in advance.

Next, the heated and pressurized resin 8 is supplied to the runner 14 via the center cal. The resin 8 flows through the runner 14, and sequentially passes through the gate 16 on the side closer to the center cal toward the closed end (tip) of the runner 14.

After that, when the runner 14 is filled with the resin 8, the sensor provided at the tip of the runner 14 detects this and outputs this detection signal to the control device. When the control device receives this detection signal, it simultaneously lowers the shielding plate 17 to make each gate 16
Open.

Then, as shown in FIGS. 2A and 2B, injection of the resin 8 from the runner 14 into each cavity 15 is simultaneously started, and the resin 8 is simultaneously advanced to each cavity 15 via each gate 16. Is injected into. Then, after the inside of each cavity 15 is filled with the resin 8, the supply of the resin 8 is stopped. The resin 8 is cooled and solidified by the upper mold 12 and the lower mold 13, and after the resin 8 is solidified, the upper mold 12 and the lower mold 13 are divided to obtain a resin molded body in which the semiconductor element 6 is embedded. You can

In this way, the resin 8 is injected into all the cavities 15 connected to each runner 14 substantially simultaneously. Therefore,
The viscosity of the resin 8 at the time of injection into the cavity 15 is
15 is substantially the same, and unlike the conventional case, the behavior and characteristics of the resin 8 injected into the cavity 15 do not differ due to the difference in the distance from the center cal to the cavity 15. This avoids the situation where the bonding wire 5 is deformed or the resin appearance is deteriorated in a specific cavity, for example, the cavity farthest from the center cal.

[Effects of the Invention] As described above, in the present invention, a plurality of cavities are injected and filled with resin substantially at the same time, and therefore, the behavior and characteristics of the resin at the time of resin injection differ among the cavities. The problem of doing is solved. As a result,
The deformation of the wire is prevented, the appearance of the resin molded body is stabilized, the quality and reliability are improved, and the resin encapsulation condition is easily set.

[Brief description of drawings]

1 (a) and 1 (b) are a plan sectional view and a longitudinal sectional view, respectively, showing an embodiment of the present invention, showing a state before resin injection, and FIGS. 2 (a) and 2 (b) respectively. FIGS. 3A and 3B are a plan sectional view and a longitudinal sectional view showing an embodiment of the present invention showing a state after resin injection, and FIGS. 3A and 3B are a plan sectional view and a longitudinal sectional view showing a conventional molding method, respectively. It is a figure. 1, 14; runner, 3, 15; cavity, 2, 16; gate, 6; semiconductor integrated circuit element, 8; resin, 17; shielding plate

Claims (1)

[Claims] 1. A transfer molding method in which heated and pressurized thermosetting resin is press-fitted from a runner into each cavity through a plurality of injection parts, and a predetermined number of injection parts are provided by providing an opening / closing means in the injection part. After the resin is supplied to the parts, the opening / closing means is opened and the resin is simultaneously injected into each cavity from the runner.