JPH04192343A - Semiconductor and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the number of steps required after a molding process by carrying transfer molding in such a manner that one end of a metal header is held by a mold and the other end is held between tablets by press pins. CONSTITUTION:A metal header 2A is placed in a mold, and it is held at one end by the mold and at the other end between tablets 5 by press pins 10. A semiconductor chip 3 on the header is sealed with resin 6 by transfer molding. Since the header is covered with the tablets, it is prevented from projecting outside. Therefore, it is not necessary to bury the exposed end of the header after transfer molding. This reduces the number of steps required after a discrete semiconductor device 1 is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and in particular to a technique that is effective when applied to a single-structure semiconductor device such as a power transistor to a transistor.

[Conventional technology]

For single-piece semiconductor devices such as resin power transistors, semiconductor pellets equipped with power transistors are made of resin (
Hermetically seal with resin package).

Semiconductor pellets are mounted on the surface of a metal header (frame). The external terminal (bonding pad) of the semiconductor pellet is electrically connected to the inner part of the lead via a bonding wire. If the power transistor mounted on the semiconductor pellet is a bipolar transistor, a collector lead is drawn out from one end of the metal header.

Each of the base lead and the emitter lead is separated from the metal header and the collector lead, and each is placed on both sides of the collector lead.

The resin of the unitary structure semiconductor device is formed by a transfer molding method. Resin sealing using this transfer molding method is performed as follows. First, a metal header and a semiconductor pellet mounted on its surface are placed in a cavity formed by an upper mold and a lower mold. Next, a fluid resin is injected into the cavity of the mold, and the fluid resin is cured. Thereafter, by removing the mold, a resin molded into the shape of the cavity of the mold is formed, and semiconductor pellets and the like are hermetically sealed inside this resin.

When a single-piece semiconductor device is encapsulated with resin using the transfer molding method described above, one end of the metal header (each lead) is held between the dams of the mold, and the other end of the metal header is held between header holding pins. do. The header holding pin has a cantilever structure when holding one end of the metal header, and the other end of the metal header moves up and down during resin sealing, so it is used to prevent this. Vertical fluctuations on the other end of the metal header cause variations in the thickness of the resin on the back side of the metal header to which the heat dissipation plate is attached, and if it is thick, the heat dissipation will decrease, and if it is thin, the insulation will decrease. do.

The header holding pin used in the resin sealing is removed together with the mold after the resin has hardened. When the header holding pin is removed, a part of the surface of the other end of the metal header corresponding to the header holding pin is exposed from the resin, so that no insulating material is formed in this exposed area. If a part of the surface of the metal header is exposed from the resin, if a high voltage is applied to the metal header, a discharge will occur between it and the heat sink during mounting, and this single structure semiconductor device will not be installed. to the circuit
゛ Malfunction occurs. As the #@ edge material, for example, a resin material applied by a dropping (so-called botting) technique and cured by a subsequent baking process is used.

Note that this type of single-piece structure semiconductor device is disclosed, for example, in Japanese Patent Application No. 1-46508.

[Problem to be solved by the invention]

The present inventor discovered the following problems in the above-mentioned single-piece structure semiconductor device.

In the single-piece structure semiconductor device described above, the metal header and the semiconductor pellet mounted on its surface are sealed with a resin formed by a transfer molding method, and then the header holding pins used for resin sealing are removed. Then, re-form the insulating material in the area where the insulation material was removed. Therefore, the number of steps required to form a semiconductor device having a single structure after resin sealing increases.

Further, since the insulating material is re-formed in the area where the header holding pin has been removed using a dripping technique, voids are likely to occur. Furthermore, since the Mf material is basically formed in a separate process from the resin used for sealing, even when the same resin material as the resin for sealing the metal header and the semiconductor pellet is used, the resin Adhesion to the area where the header holding pin was removed is poor. Therefore, in a single-piece semiconductor device, moisture easily enters through the gap between the resin and the M and II materials formed in the area where the header holding pin is removed, resulting in deterioration of moisture resistance.

An object of the present invention is to provide a semiconductor device with a single structure, 'J
The object of the present invention is to provide a technology that can reduce the number of forming steps after FDI sealing.

Another object of the present invention is to provide a technique capable of achieving the above-mentioned objects, improving heat dissipation and dielectric strength, and improving reliability of a single-structure semiconductor device.

Another object of the present invention is to provide a semiconductor device having a single structure,
The purpose of the present invention is to provide a technology that can improve moisture resistance.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

(1) While one end of the lead of the metal header is held between the metal mold and the other end of the metal header is held between the header holding pins, the metal header and the semiconductor pellet mounted on its surface are placed. In a method for forming a semiconductor device sealed with a resin formed by a transfer molding method, one end side of the metal header is held between molds, and the other end side of the metal header is held by the header holding pin with a tablet interposed. and a step of injecting a resin into the mold using a transfer molding method, sealing the metal header and the semiconductor pellet with the resin, and fixing the tablet with the resin.

(2) The tablet of the means (1) is formed of substantially the same resin material as the resin that seals the metal header and semiconductor pellet.

(3) In the semiconductor device of the means (1) or (2), a tablet fixed to resin is provided on the other end side of the metal header using the method described above.

[For production]

According to the above-mentioned means (1), a tablet is interposed in advance between the metal header and the header holding pin, and then resin is injected into the mold based on the transfer molding method to form the metal header and the semiconductor pellet. Since the tablet is fixed at the same time as the sealing, the surface of the metal header is covered with the tablet, and the surface of the metal header is no longer exposed from the resin, and the metal header is exposed again after the resin is sealed by the transfer molding method. The process of embedding the region can be eliminated, and the number of formation processes after sealing the semiconductor device with resin can be reduced.

According to the above-mentioned means (2), the properties of the resin based on the transfer molding method and the tablet are the same, and since the tablet I can be sealed and fixed together with the sealing of the resin, the adhesiveness between the resin and the tablet can be improved. It is possible to improve the moisture resistance of the semiconductor device by reducing the gap between the two.

According to the above-mentioned means (3), the above-mentioned means (1) or (2)
) In addition to the effects described above, when sealing with resin using the transfer molding method, the other end of the metal header is securely held by the header holding pin, so vertical fluctuations on the other end of the metal header are reduced. , it is possible to reduce variations in resin thickness on the front surface (semiconductor pellet mounting surface) side and the back surface side of the metal header.

As a result, the decrease in heat dissipation caused by the thickness of the back side of the resin metal header of the semiconductor device being thickened is reduced,
Further, since the reduction in dielectric strength caused by thinning can be reduced, the reliability of the semiconductor device can be improved.

Hereinafter, the configuration of the present invention will be described together with an embodiment in which the present invention is applied to a resin power 1-transistor.

In addition, in all the figures for explaining the embodiment, parts having the same functions are given the same reference numerals, and repeated explanations thereof will be omitted.

[Embodiment of the Invention] The structure of a single structure semiconductor device (resin power transistor) which is an embodiment of the present invention is shown in FIG. 1 (cross-sectional view) and FIG.
Figure (plan view with some resin removed) and Figure 3 (plan view)
Indicated by

As shown in FIGS. 1 to 3, a single-structure semiconductor device (resin power transistor) 1 has semiconductor pellets 3 mounted on the surface of a metal header (frame) 2A, and these are sealed with resin 6. Stop.

The semiconductor pellet 3 is formed of a single crystal silicon substrate.

A bipolar transistor as a power transistor is mounted on this semiconductor pellet 3. Although the detailed structure of the bipolar transistor is not shown, a single crystal silicon substrate is used as a collector region, a base region is formed on the main surface of the collector region, an emitter region is formed on the main surface of the base region, and configured. Although not shown, on the surface side of the semiconductor pellet 3, external terminals (ponding pads) connected to the emitter region and external terminals connected to the base region are arranged.

The metal ladder 2A carries the semiconductor pellet 3 and is electrically connected to the collector region of the bipolar transistor mounted on the semiconductor pellet 3. As shown in FIGS. 1 to 3, a collector lead 2C is integrally formed and electrically connected to one end of the left side of the metal ladder 2A. An emitter lead 2E and a base lead 2B are arranged on both sides (upper and lower in FIGS. 2 and 3, respectively) of the collector lead 2C. Emitter lead 2
E and the base lead 2B are arranged separately from the metal header 2A. Each of the emitter lead 2E and base lead 2B is electrically connected to an external terminal of the semiconductor pellet 3 via a bonding wire 4. The metal header 2A, collector lead 2C, emitter lead 2E,
Although the base leads 2B have different thicknesses, they are cut and molded from the same lead frame. This lead frame is made of, for example, Cu or a Cu-based alloy.

An opening 2D is formed in the central portion of the metal ladder 2A. This opening 2D is configured to form a hole (6A) when attaching the single-piece semiconductor device Wl to a metal heat sink (not shown) on the back side of the metal ladder 2A.

A tablet (an insulating material) is placed on the surface and back surface of the other end on the right side of the metal ladder 2A, that is, the area where the header holding pin (10) used for resin sealing by the transfer molding method described later comes into contact. An embedding resin body) 5 is constructed. The tablet 5 is basically formed on the front and back surfaces of the other end of the metal ladder 2A before injection of the resin 6 based on the transfer molding method, and is fixed to the resin 6 as the resin 6 hardens.

As will be described later, in this embodiment, the tablet 5 is supplied from the header holding pin (10) through the inside thereof, so the tablet 5 is smaller in size than the tip of the header holding pin (the surface facing the metal header 2A). configured. However, when the resin 6 is injected, the tablet 5 can be reliably fixed by the resin 6 as it wraps around the tablet 6. Therefore, the tablet 5 is basically constructed with a size similar to or larger than the size of the tip of the header holding pin. You may.

The tablet 5 basically has insulating properties and only needs to have heat resistance so as not to melt during resin sealing. Use materials with appropriate hardness that do not cause Furthermore, the tablet 5 is made of a material that basically has good adhesion to the resin 6 and has a linear expansion coefficient compatible with that of the resin 6 in order to prevent the occurrence of cracks. Specifically, as will be described later, the tablet 5 uses an epoxy resin as the resin 6, so the same epoxy resin is used.

Further, the tablet 5 may be formed of alumite or the like.

Since the tablet 5 is fixed to the resin 6 when the resin 6 is formed, there is basically no need to use an adhesive.

The resin 6 hermetically seals the metal ladder 2A, the semiconductor pellet 3 mounted on its surface, and the like.

This resin 6 is formed by a transfer molding method. As the resin 6, for example, an epoxy resin is used. resin 6
an opening 2D formed in the central part of the metal ladder 2A;
A mounting hole (through hole) 6A is formed at a position corresponding to , through which a screw is passed when mounting to a metal heat sink. In addition, a header holding pin (10) is provided at a position corresponding to the tablet 5 formed on the other end side of the metal ladder 2A of the resin 6.
An opening 6B is formed by using the above. This opening 6
Tablet 5 is exposed in B, but this tablet 5
Since the surface of the metal ladder 2A is covered with
The surface of the ladder 2A is not exposed to the metal from B.

Next, a method for forming the above-described single-structure semiconductor device 1 will be briefly described using FIGS. 4, 5, and 7 (cross-sectional views shown for each predetermined forming process).

First, as shown in FIG. 4, the semiconductor pellet 3 is mounted on the surface of the metal ladder 2A connected to the frame of the lead frame before cutting, and the bonding wire 4 is formed. The bonding wire 4 connects between the external terminal of the semiconductor pellet 3 and the base lead 2B, and between the external terminal and the emitter lead 2E.

Next, as shown in FIG. 5, the metal header 2A of the lead frame is placed in a cavity 9 formed by the upper mold 7 and lower mold 8 of the mold. The collector lead 2c, emitter lead 2E, and base lead 2B at one end of the metal ladder 2A are held between the dam portions of the upper mold 7 and lower mold 8, respectively. The other end side of the metal ladder 2A is held by a header holding pin 10 with a tablet 5 interposed therebetween.

The tablet 5 interposed between the metal ladder 2A and the header holding pin 10 is as shown in FIG. Then, it is supplied to the tip side through the inside of the header holding pin 10. Each of the upper mold 7 and lower mold 8 of the mold is mainly composed of, for example, an Fe-based metal material with a Cr plating plate provided on the surface.

The header holding pins 10 are separately fixed to each of the upper die 7 and the lower die 8, and are made of, for example, an Fe-based metal material. The tablet 5 is supplied from the outside of the mold for each resin sealing process based on the transfer molding method, and is conveyed and supplied inside the header holding pin 10 by the shaft 12 of the cylinder 11. The cylinder 11 is mounted on the main body frame of the resin sealing device 13 using, for example, a hydraulic cylinder or a pneumatic cylinder.

Next, based on the transfer molding method, a fluid resin is injected into the cavity 9 of the mold, and this resin is cured to form a resin 6, and the tablet 5 is fixed with the resin 6.

Next, as shown in FIG. 7, after the resin 6 has hardened, the upper mold 7 and the lower mold 8 are each removed from the mold, and the header holding pin 10 is also removed. When removing the header holding pin 10, since the tablet 5 is fixed and integrated with the resin 6, only the header holding pin 10 is removed.

Thereafter, the collector lead 2C, emitter lead 2E, and base lead 2B are each separated from the frame of the lead frame. Through this cutting step, the semiconductor device 1 having a unitary structure shown in FIGS. 1 to 3 described above is completed.

In this way, one end of the drawer side of the lead (2C12E and 2B) of the metal ladder 2A is held between the molds (A, 8), and the other end of the metal ladder 2A is held between the header holding pins 10. In the method for forming a semiconductor device 1 in which the metal ladder 2A and the semiconductor pellet l-3 mounted on the surface thereof are sealed with a resin 3 formed by a transfer molding method, one end side of the metal ladder 2A is sealed. A step of clamping the metal header 2A with a mold and also clamping the other end side of the metal header 2A with the header holding pin 10 with a tablet 5 interposed therebetween, and injecting resin 6 into the mold based on a transfer molding method, The metal ladder 2A and the semiconductor pellet 3 are transferred to the resin 6.
and sealing the tablet 5 with a resin 6. With this configuration, the metal ladder 2
A tablet 5 is interposed in advance between A and the header holding pin 10, and then a resin 6 is injected into the mold based on the transfer molding method to seal the ladder 2A and the semiconductor pellet 3 to the metal, and the above-mentioned Since the tablet 5 is fixed, the surface of the ladder 2A to the metal is covered with the tablet 5, and the surface of the ladder 2A is no longer exposed from the resin 6 to the metal. The step of burying the exposed region of the ladder 2A can be eliminated, and the number of forming steps after sealing the resin 6 of the semiconductor device 1 having a single structure can be reduced.

Furthermore, the tablet 5 is made of substantially the same resin material as the resin 6 that seals the metal ladder 2A and the semiconductor pellet 3. With this configuration, the properties of the resin 6 and the tablet 5 based on the transfer molding method are equal,
In addition, since the tablet 5 can be sealed and fixed together with the resin 6, the adhesiveness between the resin 6 and the tablet 5 can be improved.
The gap between the two can be reduced, and the moisture resistance of the semiconductor device 1 having a single structure can be improved.

Further, in the single-piece structure semiconductor device 1, the tablet 5 fixed to the resin 6 is provided on the other end side of the metal header 2A using the method described above. With this configuration, in addition to the above-mentioned effects, when sealing the resin 6 by the transfer molding method, the other end side of the metal ladder 2A is attached to the header presser pin 1.
Since it is securely clamped at 0, the vertical fluctuation on the other end side of the metal ladder 2A is reduced, and the thickness of the resin 6 on the front side (the mounting surface of the semiconductor pellet 3) and the back side of the metal ladder 2A is reduced. It is possible to reduce the variation in As a result, the thickness of the back side of the metal ladder 2A of the resin 6 of the single-piece structure semiconductor device 1 reduces the decrease in heat dissipation due to the increase in thickness, and also reduces the decrease in the #@ edge breakdown voltage due to the decrease in thickness. Since it can be reduced, the reliability of the semiconductor device 1 having a single structure can be improved.

The invention made by the present inventor has been specifically explained above based on the above embodiments, but the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof. Of course.

For example, the present invention can be applied to a single-piece semiconductor device in which an MTSFET is mounted as a power transistor on a semiconductor pellet.

Further, the present invention is not limited to a single structure semiconductor device,
It can be widely applied to semiconductor devices that are resin-sealed using transfer molding.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

In a single structure semiconductor device, the number of formation steps after resin sealing can be reduced.

Furthermore, in the single-piece structure semiconductor device, heat dissipation and dielectric strength can be improved, and reliability can be improved.

Further, in the single-piece structure semiconductor device, moisture resistance can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a single-piece structure semiconductor device according to an embodiment of the present invention, FIG. 2 is a plan view of the single-piece structure semiconductor device with a part of the resin removed, and FIG. FIGS. 4, 5, and 7 are plan views of the single-piece structure semiconductor device, and sectional views showing each step for explaining the method for forming the single-piece structure semiconductor device. FIG. 6 is a sectional view of a main part of the unitary structure semiconductor device at a predetermined formation process. In the figure, Engineering...Single structure semiconductor device, 2A...Metal header, 2B, 2C, 2E...Lead, 2D, 6B...
... Opening, 3... Semiconductor pellet, 4... Bonding wire, 5... Tablet, 6... Resin, 6A...
... Mounting is through holes, 7... Upper mold, 8... Lower mold, 9...
Cavity, 10...Header holding pin.

Claims (1)

[Claims] 1. One end of the lead-out side of the lead of the metal header is held between the molds, and the other end of the metal header is held between the header holding pins, and the metal header is mounted on the metal header and its surface. In a method for forming a semiconductor device in which a semiconductor pellet is sealed with a resin formed by a transfer molding method, one end side of the metal header is held between molds, and the other end side of the metal header is held with a tablet interposed. The method includes a step of holding the header with the header holding pins, and a step of injecting a resin into the mold based on a transfer molding method, sealing the metal header and the semiconductor pellet with the resin, and fixing the tablet with the resin. A method for forming a semiconductor device, characterized in that: 2. The method of forming a semiconductor device according to claim 1, wherein the tablet is formed of substantially the same resin material as the resin that seals the metal header and the semiconductor pellet. 3. A semiconductor device comprising a tablet fixed to resin at the other end of the metal header by the method described in claim 1 or claim 2.