JPH07221236A - Method for manufacturing resin-sealed semiconductor device and lead frame - Google Patents

Abstract

(57) [Abstract] [Purpose] A resin-sealed semiconductor device for a semiconductor surge absorption module with three elements, which solves the above problems and enables mass production of products with stable characteristics and reliability with high production efficiency. A method for manufacturing the same is provided. [Structure] Three substrate supports 5a to 5c, external leads 6,
And a first lead frame 9 in which tie bars 9a and 9b are patterned, and a second lead frame 1 in which connectors 7, tabs 10a and tie bars 10b are patterned.
0, the semiconductor device pellets 4a to 4c are sandwiched between the first lead frame and the second lead frame on both main surfaces thereof, and the semiconductor device pellet is die-bonded to the substrate support and the connector. Then, the semiconductor element pellet, the substrate support, the connector, and a portion of the external lead are sealed with the resin 8 in the peripheral region, and further tie bar cut and tab cut are performed to produce a resin-sealed semiconductor device product. Is assembled and completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a resin-sealed semiconductor device for a semiconductor surge absorption module or the like which is constructed by combining three semiconductor surge absorption elements,
And a lead frame used for manufacturing the same.

[0002]

2. Description of the Related Art A surge absorbing circuit having a structure as shown in FIG. 5 is known as a means for protecting an electronic device connected to a power source from external lightning, internal lightning surge and the like. In the figure, 1 is a power supply, 2 is a protected device, 3 is a surge absorption circuit, and the circuit 3 has three semiconductor surge absorption elements having the same characteristics (bidirectional thyristor, Zener diode, etc.)
After interconnecting 3a to 3c in a star shape, each element is connected between the wiring lines T and L and the ground E as shown. With this circuit configuration, the surge that enters the wiring line is T-
It is absorbed between E, LE and TL. The operation of the surge absorbing circuit is well known, and its description is omitted here.

Next, the structure of a resin-sealed semiconductor device in which the surge absorbing circuit is modularized is shown in FIGS.
Shown in. In the figure, 4a to 4c are a total of three semiconductor element pellets corresponding to the semiconductor surge absorbing element described above,
5a to 5c are substrate supports (die pads) on which the semiconductor element pellets 4a to 4c are individually mounted one by one, 6
Is an external lead connected to one end of each substrate support 5a-5c and pulled out in the same direction, and 7 is a semiconductor element pellet 4a-4c.
An external T-shaped connector, which is overlapped on the upper surface of the semiconductor element pellets 4a to 4c, the substrate supports 5a to 5c, the connector 7, and a part of the external lead 6 on the root side. Then, the sealing resin is molded in the peripheral region.

By the way, conventionally, the resin-encapsulated semiconductor device having the above structure is assembled by the following method. That is, in addition to the semiconductor element pellets having the same rating as the components to be supplied to the assembly process, the substrate supports 5a to 5 described in FIG.
c, a lead frame in which the external leads 6 are patterned,
Also, a connector 7 having a T-shaped outer shape is prepared as a single component. This lead frame is the lead frame 9 shown in FIG.
The lead frame 9 has the above-mentioned substrate supports 5a to 5c and the external leads 6, and two tie bars 9a and 9b for connecting the external leads 6 to each other. The tie bars 9b are used as the side rails of the lead frame, and the alignment holes 9c are opened here at regular intervals.

Then, in the first step, the lead frame 9
Of the semiconductor element pellets 4a-4 on the substrate supports 5a-5c of
Each c is mounted by sandwiching a solder plate (not shown), and then the connector 7 is mounted on each of the semiconductor element pellets 4a to 4c by sandwiching the solder plate. The semiconductor element pellets are die-bonded to the substrate support and the connector by passing through an attachment furnace. Next, the assembly is transferred to a transfer molding step, where the semiconductor element pellet, the substrate support, the connector, and a part of the external lead are encapsulated with a resin in the peripheral region, and then the final step is performed. Then, the tie bars 9a and 9b of the lead frame 9 are cut to complete the product shown in FIG.

[0006]

The conventional manufacturing method described above has the following problems in terms of productivity, product characteristics, and reliability. 1) In the first assembly process, the substrate support with external leads can be continuously supplied as a lead frame, but the connectors are handled by hand one by one and the components are positioned and mounted on the semiconductor element pellets. Need to be placed. Therefore, the work efficiency is low and the mass productivity of the products is low.

2) A jig or the like is used to position the connector with respect to the semiconductor element pellet. Since the connectors are placed on the pellet in a state of being separated one by one, it is easy to move freely. The position often shifts or tilts during transfer to the next soldering process.
Therefore, in the assembled state, the insulating distance between the connector and the substrate support is partially insufficient and a short circuit occurs when a voltage is applied. For example, a product having defects in terms of characteristics and reliability is likely to occur. Yield rate decreases.

3) Further, the external lead drawn out from the substrate support is elongated, and in particular, the external lead 6 of the substrate support 5a located at the center in the configuration of FIG. 6 has a large length dimension and is easily bent. Therefore, when the temporary assembly is inserted into the molding die and the molding resin is injected in the transfer molding process, the external lead is deformed by the flow of the resin, and as a result, the soldered portion is peeled off, The problem arises that the insulation strength of the sealing resin varies and the insulation strength decreases.

The present invention has been made in view of the above points, and aims at the above-mentioned three-element semiconductor surge absorption module and the like to solve the above problems and efficiently produce a product having stable characteristics and reliability. An object of the present invention is to provide a method for manufacturing a resin-encapsulated semiconductor device that can be mass-produced, and a lead frame.

[0010]

In order to achieve the above object, according to the manufacturing method of the present invention, a plurality of substrate supports, external leads drawn from each substrate support, and external leads are interconnected. Using a first lead frame in which a tie bar is patterned, a connector, a tab extending from one end of the connector, and a second lead frame in which a tie bar for interconnecting the tabs is patterned. The first lead frame and the second lead frame are superposed on both main surfaces of the pellet sandwiched, and the semiconductor element pellet is die-bonded to the substrate support of the first lead frame and the connector of the second lead frame. Then, the semiconductor element pellet, the substrate support, the connector, and the resin encapsulation of the peripheral area including a part of the external lead, and the tie bar of the first lead frame. It shall perform cutting, a tab cut in the second lead frame.

In the above manufacturing method, the semiconductor element pellets are die-bonded to the first and second lead frames in the first step, the tabs of the second lead frame are cut in the second step, and the third step is performed. In the process of transfer molding method, semiconductor element pellets, substrate supports, connectors,
Also, it is preferable that a part of the peripheral area of the external lead is sealed with resin and the tie bar of the first lead frame is cut in the fourth step.

Further, regarding the first lead frame used in the above-described manufacturing method, according to the present invention, the cross-sectional shape of the external lead drawn from the substrate support is subjected to bending in order to prevent the external lead from being deformed during molding. The groove section has a large section modulus, and the groove section formed on the outer lead may be formed in the range between the substrate support and the tie bar interconnecting the intermediate portion of the outer lead. it can.

[0013]

In the above-described manufacturing method, the substrate support with external leads, which is bonded to both the front and back main surfaces of the plurality of semiconductor element pellets, and the connector are patterned on the first and second lead frames, respectively. By assembling a semiconductor device using this lead frame, each component other than the semiconductor element pellets is handled not as a single body but as a continuous lead frame, so that automation of the assembly process can be easily handled. Moreover, since the first and second lead frames are continuously supplied to the assembling process in synchronism with each other, the alignment is ensured, and the semiconductor element pellets are transferred to the soldering process while being sandwiched between the lead frames, so that the predetermined positions are maintained. Therefore, there is little risk of undue displacement from the above, and it becomes easy to ensure high parallelism between the substrate support and the connector.

In addition, since the external lead drawn from the substrate support has a groove-shaped cross section (for example, a V-shaped cross section), the external lead has a large cross-section coefficient against bending, so that the external lead is subjected to transfer molding. Is unlikely to be deformed, which prevents product defects due to deformation of the external leads.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings for the surge absorbing module shown in FIG. In the drawings of the embodiments, the same members corresponding to FIG. 6 are designated by the same reference numerals. FIG. 1 shows three semiconductor device pellets 4a.
3 to 4c and the first lead frame 9 shown in FIG.
2 shows a temporary assembly state in which the die assembly is performed by sandwiching the die assembly with the second lead frame 10 shown in FIG. Here, the first lead frame 9 includes three substrate supports 5a to 5c arranged at regular pitches, and one end of each of the substrate supports 5a to 5c is connected to the substrate support in the same direction. The pulled-out external lead 6, two tie bars 9a and 9b interconnecting the middle portion and the tip portion of the external lead 6, and a positioning hole 9c formed in the tie bar 9b are continuously formed in a pattern. On the other hand, the second lead frame 10 has T-shaped connectors 7 arranged at regular pitches corresponding to the substrate supports 5a to 5c formed on the first lead frame 9 and one end of the connector 7. External lead 6 in a row
And a tie bar 10b (also serving as a side rail) interconnecting the tabs, and a positioning hole 10c formed in the tie bar 10b.
Are continuously patterned.

In the first assembling process, the first lead frame 9 and the second lead frame 10 are used as parts.
Then, the semiconductor element pellets are supplied, and the semiconductor element pellets 4a to 4c are mounted one by one on the substrate supports 5a to 5c formed on the first lead frame 9 with a solder plate (not shown) interposed therebetween. The semiconductor element pellets 4a to 4c are stacked on top of each other so that the connector 7 formed on the second lead frame 10 is sandwiched between the solder plates, and the pellets are first stacked.
It is sandwiched between the lead frame 9 and the second lead frame 10. In addition, the lead frames 9 and 10 are continuously supplied while performing relative alignment through the pins of the assembly jig into the alignment holes 9c and 10c formed in the tie bar.

In the next step, the semiconductor element pellets 4a ...
The semiconductor element pellets 4a to 4c are die-bonded to the substrate supports 5a to 5c and the connector 7 while passing 4c through the soldering furnace while being sandwiched between the lead frames 9 and 10. Then, the process proceeds to a molding step, the resin is inserted into the transfer molding die and the molding resin is injected, the semiconductor element pellets 4a to 4c, the substrate supports 5a to 5c, the connector 7,
Also, a part of the peripheral area of the outer lead 6 on the root side is sealed with the resin 8. Finally, the tie bars 9a, 9 of the first lead frame 9
b and the tab 10a of the second lead frame 10 in FIG.
The product shown in FIG. 6 is completed by cutting along the cutting line xx indicated by the chain line in (a).

Next, application examples of the present invention will be described. That is, in contrast to the second lead frame 9 described above, in this embodiment, as shown in FIGS. 4 (a) and 4 (b), a part of the external lead 6 is represented by a groove-shaped cross section represented by reference numeral 6a, for example, It is pressed into a V-shaped cross section. This press working can be performed simultaneously with the punching process by pressing the lead frame.

Thus, the groove-shaped cross section 6a is formed on the outer lead 6.
By forming, the section modulus against bending of the portion becomes large and it becomes difficult to bend. As a result, it is possible to prevent the external leads 6 inserted into the mold during transfer molding from being easily deformed by being pushed by the molding resin flow injected into the mold. It should be noted that it is sufficient to form the groove-shaped cross-section 6a in a region to be inserted into the mold at the time of transfer molding, and actually, as shown in the drawing, the substrate supports 5a to 5a.
It is preferable to form and implement in the range between c and the intermediate tie bar 9a which functions as a dam bar. Further, the shape of the groove-shaped cross section is not limited to the V shape shown in the figure, and the cross section U
Even if it is a character shape, the bending strength can be similarly enhanced.

Further, by adopting the one shown in the embodiment of FIG. 4 as the first lead frame 9, the above-mentioned semiconductor device assembling process is partially changed in order as follows. It can be carried out. That is, in the first step,
Similar to the assembly method described above, the semiconductor element pellets 4a to 4a
After c is assembled on the first and second lead frames 9 and 10 and die-bonded, the tab 10a of the second lead frame 10 is cut at the root portion of the connector 7 in the subsequent second step to form the tie bar 10b. Detach. Then, in this state, the peripheral parts of the semiconductor element pellet, the substrate support, the connector, and the external leads are resin-sealed by the transfer molding method in the third step, and the first lead is formed in the final fourth step. The tie bars 9a and 9b of the frame 9 are cut.

By assembling the semiconductor device in this order of steps, the tabs of the second lead frame 10 are already cut during transfer molding, so that the metal parts other than the external leads 6 are exposed to the outside from the sealing resin 8. A full mold package that does not require is possible. Moreover, as described with reference to FIG. 4, a grooved portion 6a is formed on the outer lead 6 in advance with respect to the first lead frame 9 to increase its bending strength, so that it is inserted into the molding die. However, the substrate support, the semiconductor element pellet, and the tab-cut connector can be stably supported in a cantilever manner by the external lead itself.

[0022]

As described above, according to the manufacturing method of the present invention, since the connector, which is an assembly component, is molded and handled on the lead frame like the substrate support, it can be handled as in the conventional case. It is not necessary to manually attach each connector, which is one component, one by one, and this makes it possible to easily support full automation of the assembly process. In the temporary assembly process, multiple semiconductor element pellets and connectors can be freely used. Such movement can be restrained by the tie bar of the lead frame, the connector, the semiconductor element pellet, and the substrate support can be stably held in a parallel position at a fixed position, and soldering can be performed in the next step. Also,
Especially for external leads drawn from the substrate support, by increasing the bending strength of the elongated leads with a groove-shaped cross section, the effect of preventing bending of the external leads in the resin sealing process can be obtained. According to the invention, for a semiconductor surge absorption module or the like consisting of three elements,
A resin-encapsulated semiconductor device can be manufactured with a high yield rate and high mass productivity.

[Brief description of drawings]

1A and 1B are diagrams showing a temporary assembly state of a resin-encapsulated semiconductor device according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side view.

FIG. 2 is a pattern development view of the first lead frame in FIG.

FIG. 3 is a pattern development view of a second lead frame in FIG.

FIG. 4 is a pattern development view of an application example of the second lead frame in FIG.

FIG. 5: Surge absorption circuit diagram composed of three semiconductor surge absorption elements

6A and 6B are configuration diagrams of a resin-encapsulated semiconductor device to which the present invention is applied, in which FIG. 6A is a partially cutaway plan view, FIG. 6B is a sectional side view, and FIG. Exploded perspective view, (d) external view of the product

[Explanation of symbols]

 4a, 4b, 4c Semiconductor element pellet 5a, 5b, 5c Substrate support 6 External lead 7 Connector 8 Sealing resin 9 First lead frame 9a, 9b Tie bar 10 Second lead frame 10a Tab 10b Tie bar

Claims (4)

[Claims] 1. A plurality of semiconductor element pellets are mounted between a plurality of leaded substrate supports individually corresponding to each pellet and a connector commonly extending between the pellets, and a peripheral region thereof is resin-sealed. And a first lead frame having a plurality of substrate supports, external leads drawn from each substrate support, and a tie bar for interconnecting the external leads, which is patterned, A connector, a tab connected to one end of the connector, and a second lead frame having a pattern formed with a tie bar interconnecting the tabs are used to sandwich the semiconductor element pellet on both main surfaces thereof. After stacking the lead frame and the second lead frame, the semiconductor element pellet is die-bonded to the substrate support of the first lead frame and the connector of the second lead frame. In the above, the semiconductor element pellet, the substrate support, the connector, and the resin encapsulation of the peripheral area including a part of the external lead, the tie bar cut of the first lead frame, and the tab cut of the second lead frame are performed. And a method for manufacturing a resin-encapsulated semiconductor device. 2. The manufacturing method according to claim 1, wherein the semiconductor element pellet is die-bonded to the first and second lead frames in the first step, and the tab of the second lead frame is cut in the second step, In the third step, the semiconductor device pellet, the substrate support, the connector, the transfer mold method,
And a method for manufacturing a resin-sealed semiconductor device, characterized in that a part of the peripheral area of the external lead is resin-sealed and the tie bar of the first lead frame is cut in the fourth step. 3. A first method used in the manufacturing method according to claim 1.
2. The lead frame of a resin-encapsulated semiconductor device according to claim 1, wherein the external lead drawn out from the substrate support has a groove-shaped cross section having a large section modulus against bending. 4. The lead frame according to claim 3, wherein
A lead frame for a resin-sealed semiconductor device, wherein a groove-shaped cross section formed in the external lead is formed in a range between a substrate support and a tie bar interconnecting an intermediate portion of the external lead.