JPS5940289B2 - Manufacturing method for resin-sealed semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a resin-sealed semiconductor device using a long film-like lead frame.

Resin-sealed semiconductor devices can be manufactured more easily in mass production than metal-sealed semiconductor devices, and are also more advantageous than metal-sealed semiconductor devices in terms of cost. In recent years, surface stabilization processing technology for semiconductor elements has significantly advanced, and most semiconductor devices, except for special semiconductor devices, now have a resin-sealed structure. FIG. 1 is a diagram showing the structure of a lead frame used in manufacturing a resin-sealed semiconductor device, such as a typical low-power transistor. This 9-fold frame has a large number of leads extending in the same direction from the common connection 1, for example, leads 2, 3 and 4 form one transistor support, but usually 20
It has ~30 transistor supports. In the figure, reference numeral 5 indicates bridging strips for reinforcing the leads and keeping the distance between the leads constant, and reference numeral 6 indicates a hole into which a transfer pin is inserted for transferring the lead frame at an equal pitch during the assembly process. By the way, the lead frame shown in the figure is formed as a single piece by punching a single metal plate, and when manufacturing a transistor using such a lead frame, the lead frame is assembled using a loading device. It is continuously fed into the device and transferred sequentially.

When such a lead frame is used, the die bonding process in which the semiconductor substrate is bonded to the substrate support part of the 9-board frame and the wire bonding process in which the electrodes on the semiconductor substrate and the external leads are connected using thin metal wires are all automated. This significantly improves productivity.

However, even with a 9-frame frame that allows assembly of 20 to 30 transistors, if the index of die bonding work and wire bonding work is further increased, it must be supplied frequently, and lead A problem arises in that the frame supply device must be constantly monitored. Furthermore, since the various assembly operations for assembling the transistors are discontinuous, there remains the problem that handling of the lead frame is added during this time, making the entire operation complicated. In addition, it is necessary to pay close attention to the handling of the lead frame immediately after die bonding or wire bonding, as well as immediately after die bonding or wire bonding1.For this reason, overall workability is sufficiently improved. There were also problems that could not be solved. The present invention provides a method for manufacturing a resin-sealed semiconductor device that can eliminate all of the problems that remain in the manufacturing method using the conventional lead frame described above. In this method, a long film-like lead frame is first formed into a roll, and in the process of winding it in one direction, assembly work including sealing work with resin is performed continuously.

The manufacturing method of the present invention will be explained in detail below with reference to the drawings. FIG. 2 is a diagram showing a lead frame of a low power transistor used in the manufacturing method of the present invention.1 Its basic structure is the same as the conventional one shown in FIG. , one transistor support part is formed by the leads 2, 3, and 4, and the transistor element substrate is adhered to the tip of the lead 3 in the center, and the electrodes on the transistor element substrate are bonded with wind wires. The structure is such that it is connected to the tips of leads 2 and 4.

Incidentally, the total length of the illustrated lead frame is extremely long, for example, about 200 m, and this lead frame has an extremely large number of transistor support parts, about 30,000 pieces. Then, such a long lead frame is made into a roll-shaped body as shown in figure 7.
During assembly, the lead frame is continuously transported in the direction of arrow X and is wound up to form a roll-shaped body 8 of the assembled lead frame. FIG. 3 is a principle diagram for explaining the manufacturing method of the present invention for manufacturing a transistor using the cheese frame shown in FIG. The frame 10 is
It passes through the die bonding part 11, the wire bonding part 12, the primary sealing mold 13 made of powdered resin, and the secondary sealing part 14 made of molding resin, and is wound around the shaft body 15 to form a roll-shaped body 8 of, for example, about 75 cm. It has a diameter.

By the way, in the process shown in FIG. 3, the adhesion of the transistor element substrate to the die bond part 11 and the connection with the thin metal wire to the wire bond part 12 are the same as in the case of using a conventional lead frame. The resin sealing in the primary sealing part 13 and the secondary sealing part 14 through which the frame passes is also different from the usual method. FIG. 4 is a diagram for explaining the configuration of the primary sealing part 13 and the state of resin sealing in this part. The primary sealing part is filled with thermosetting powder epoxy resin 16. Powder resin container 17
and a heating element 1 that heats the lead frame 10 to a predetermined temperature.
Furthermore, the powder resin container 17 is provided with an air supply pipe 19 for feeding air into the filled powder epoxy resin and stirring it.

The resin sealing in the primary sealing portion will be specifically explained below. As shown in the figure, the portion of the lead frame 10 located at the primary sealing portion where the adhesion of the transistor element substrate 20 and the predetermined connection using the thin metal wire 21 such as a gold wire have been completed is heated by the heating element 18 to It is heated to a temperature of approximately .degree. C., and its tip is positioned on a powder resin container 17 filled with powdered epoxy resin 18.

By the way, the particle size of the powdered epoxy resin 16 is ≠50-4I
-100, and is constantly bubbled by air being fed from an air supply pipe 19 provided at the bottom of the powder resin container 10. This powdered epoxy resin is heated and adheres to the tip of the lead frame that passes over this powdered resin container, that is, the transistor element part, and melts.
Form a resin coating layer. This coating resin is then cured by heating the lead frame. In the figure, reference numeral 22 denotes the resin coating formed in the primary sealing portion in this manner.
However, it is desirable that the covering formed by this primary sealing part be complete, and if the sealing parts shown in the figure are arranged in two or three consecutive places and the lead frame is passed over them, The transistor element portion is sealed in multiple layers, and the above object is achieved. The method of using powdered resin as described above is extremely convenient in terms of workability and productivity for resin sealing of lead frames to which a large number of transistor elements are bonded.
After the transistor element part is coated with the resin coating 22 in this way, it is then injection sealed in the secondary sealing part, and in this secondary sealing part, the particle size is ≠ 1.
Injection molding and sealing is performed using a powdered thermoplastic resin having a melting point of about 270°C.

FIG. 5 is a diagram for explaining the state of such secondary sealing, in which the transistor element portion after the eleventh sealing is placed in the cavity formed by the injection molds 23 and 24, Molding is performed by injecting the resin 26 into the injection hole or cavity of the injection body 25. For this secondary sealing, for example, the temperature of the mold is maintained at about 150°C, and the temperature is increased from 100 to 300 Kf/
This is done by injecting the resin into a mold at high pressures in the Cd range. That is, in this process, approximately 270
℃ thermoplastic resins cure rapidly in molds at lower temperatures, and resin sealing can be performed quickly at high pressures, which is extremely advantageous for mass processing. Resin sealing with a thermosetting resin has already been performed in the primary sealing process mentioned above, and the sealing with this thermosetting resin exhibits a stable sealing state. The transistor element portion is completely protected even during a rapid resin encapsulation process under extremely high pressure. Therefore, using powdered thermosetting resin for primary sealing and molding thermoplastic resin for secondary sealing is extremely meaningful in terms of stably performing large-scale sealing processing. It is. By the way, in FIG. 3, for convenience of explanation, a state in which the lead frame passes continuously from the wire bonding part 11 to the secondary sealing part 14 is shown, but in the primary sealing and secondary sealing processes, 150 It is necessary to perform a heat treatment for curing for more than 30 minutes at a temperature of about °C.

Therefore, in actual assembly, it is necessary to separate the steps up to the wire bonding step, the primary sealing step, and the secondary sealing step. In other words, the wire-bonded lead frame is first wound up with a silicon rubber spacer sandwiched between them, and then it is continuously sealed at the primary sealing part, and the sealed lead The frame is wound again and in this state is subjected to a heat treatment for curing, and then a transistor is formed by sealing the secondary sealing portion and subjecting it to heat treatment for curing. FIG. 6 is a diagram showing a perspective view of a transistor actually formed through the above steps.
is the outer shell sealed with resin. After this, common connection part 1
Individual transistors can then be obtained by cutting and removing the bridging strips. As explained above, according to the manufacturing method of the present invention, all the assembly processes are performed using a long lead frame, and in particular, even the resin sealing process is made force-operated, resulting in a significant production increase. There is an improvement in sexual performance.

In addition, a single transfer of the lead frame to the primary or secondary sealing process increases the processing capacity of the primary sealing part and increases the number of injection molds for the secondary sealing part. By creating a possible structure, the number of pitches can be increased to several tens of pitches.
Furthermore, in the manufacturing method of the present invention, the lead frame is handled in a rolled state, which greatly simplifies the handling, which also greatly contributes to improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a known lead frame for small signal transistors, FIG. 2 is a diagram showing a lead frame used in the manufacturing method of the present invention, and FIG. 3 is a diagram for explaining the manufacturing method of the present invention. , Fig. 4 is a diagram for explaining the primary resin sealing process of the present invention, Fig. 5 is a diagram for explaining the secondary resin sealing process, and Fig. 6 is a diagram for explaining the secondary resin sealing process of the present invention. FIG. 2 is a perspective view of the semiconductor device in a stopped state; 1... Common connection part, 2-4... Lead, 5... Bridging strip, 6... Hole, 7, 8
...Roll state, 9,15...Shaft body,
10...Lead frame, 11...Dice bond part, 12...Wire bond part, 13
...Primary sealing part, 14...Secondary sealing part, 16...Thermosetting powder epoxy resin, 17.
... Powder resin container, 18 ... Heating body, 1
9...Air supply pipe, 20...Transistor element substrate, 21...Thin metal wire, 22
... Resin coating, 23, 24 ... Injection mold, 25 ... Injection body, 26 ...
Thermoplastic resin, 27... Resin-sealed outer shell.

Claims (1)

[Claims] 1. In the process of fixing one end of the rolled film lead frame to another shaft and winding it around this shaft,
A step of continuously bonding the semiconductor substrate to the tip of the lead part of the lead frame and connecting the bonded electrode on the semiconductor substrate with other leads using thin metal wires, and forming a roll-shaped lead frame through the same process. One end is fixed to another shaft, and in the process of winding it onto this shaft, the lead frame is passed through a primary resin sealing section that includes a powder resin container that stores powdered resin and agitates air, and a lead frame heating element. , a first resin sealing step in which the tips of the lead portions are coated with resin through heat treatment, and one end of the lead frame, which has been made into a roll through the same step, is fixed to another shaft, and wound around this shaft. A resin-sealed semiconductor device comprising a second resin-sealing step in which the resin-coated portion of the lead frame is placed in an injection mold and sealed with a thermoplastic resin in the process of removing the resin-sealed portion of the lead frame. Production method.