JP3469840B2 - Semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device formed by housing a metal base on which a semiconductor chip is mounted in a resin case and leading out external terminals.

[0002]

2. Description of the Related Art Cross-sectional views of a conventional semiconductor device are shown in FIGS. Reference numeral 1 denotes a metal base, and the semiconductor chip 2 is fixed to the upper surface of the semiconductor chip by soldering. There are cases where the semiconductor chip 2 is fixed via an insulating layer and cases where the semiconductor chip 2 is not interposed. The terminal fitting 3 embedded and fixed in the resin case frame 4 is bent and extended toward the center of the resin case to be formed as a first electrode, and is connected to the semiconductor chip 2 on the first electrode as shown in FIG. The bonding wire 7 is fixed. There is a case where the terminal fitting 3 is fixed to the upper surface of the semiconductor chip 2 with the solder 8 as shown in FIG. 5, but in this case, the height of the upper surface of the semiconductor chip 2 plus the thickness of the solder 8 is a horizontal plane. It is important that the terminal fittings 3 are accurately formed by being embedded in the resin case frame 4 so that the lower surface heights of the terminal fittings 3 are the same. When finished in a state in which the solder 8 is pressed onto the solder 2, insufficient thickness of the solder 8 occurs and a connection failure occurs. Further, if a gap is formed between the semiconductor chip 2 and the terminal fitting 3 due to lack of solder, crevice corrosion may proceed to promote damage. Further, in the case of connecting with the bonding wire 7 of FIG. 4, it causes abnormal heat generation in this connection portion where a large current is concentrated, and the diameter of the bonding wire 7 is increased in the power semiconductor chip 2, but There was a limit.

[0003]

SUMMARY OF THE INVENTION As described above, the terminal fitting extended and embedded in the upper surface of the semiconductor chip with poor dimensional accuracy causes defective soldering with the semiconductor chip.
This was a cause of damage to semiconductor chips due to poor connections and crevice corrosion. In addition, the maximum limit of the current value determines whether or not the bonding wire can be connected, and when the current value exceeds the limit, the wire is heated and the wire is heated at the wire connecting part, resulting in disconnection at the connecting part. The solution to these was an issue.

[0004]

In order to solve the above-mentioned problems, a semiconductor chip provided on a metal base, a terminal fitting wired and led from the semiconductor chip, and a resin case frame for fixing the terminal fitting. In a semiconductor device in which a metal base and a resin case frame are fixed to each other, one end of the terminal fitting is led out as an external terminal and the other end is projected and exposed inside the resin case frame and is a flat plate as a bonding wire connecting surface. Forming a first electrode in the form of a wire, extending the tip of the first electrode to form a second electrode as a lap joint for soldering, and connecting the semiconductor chip and the terminal fitting from the first electrode , It is possible to solder directly from the second electrode or select two construction methods with one terminal fitting.

In order to ensure that the tips of the terminal fittings are arranged on the same horizontal surface with respect to the upper surface of the semiconductor chip, the terminal fittings embedded and fixed are bent in a flat plate shape. In order to correct the dimensional difference between the horizontal plane of the first electrode and the horizontal plane of the upper surface of the semiconductor chip, a bent portion is formed in the first electrode, and a step or an inclination is provided to form a first portion.
The tip of the electrode is extended to form the second electrode.

In the third aspect, it is necessary to distinguish between the ideal state in which the second electrode is accurately arranged on the upper surface of the semiconductor chip and is soldered, and the case in which the manufacturing surface is uneven and the soldering surface is in a bad state. Therefore, by considering the second electrode as a flat plate having a hole, it is possible to control the quality against manufacturing variations by distinguishing whether the surplus solder comes out from the hole or is insufficient at the time of completion of soldering. ing.

In the fourth aspect, the second electrode is formed in a comb shape so that the finished state of the soldering can be clearly confirmed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment according to the present invention will be described with reference to FIG. Reference numeral 1 denotes a metal base, to which a semiconductor chip 2 is fixed directly or via an insulating layer, and is wired to a terminal fitting 3. The resin case frame 4 is fixed by embedding or embracing the terminal fitting 3 and at the same time being fixed to the metal case 1. One end portion of the terminal fitting 3 is led out as an external terminal, and the other end portion is bent at a substantially right angle from the embedded resin case frame and protrudes into the resin case to form a bonding wire 7 for connection with the semiconductor chip 2. A fixed plate-shaped first electrode 5 is formed, the tip of the first electrode is extended and the second electrode 6 is formed, and it functions as a lap joint for soldering on the upper surface of the semiconductor chip.

The condition required for the first electrode 5 is that the protruding length is equal to or larger than the position where bonding can be performed from the inner side surface of the resin case frame 4 with the shortest dimension, and the tip of the jig of the bonding machine is the resin case frame. The length dimension is determined on the condition that the upper surface of the first electrode is reached without hitting the inner wall of No. 4. Further, it is a necessary condition that the bottom horizontal portion of the resin case frame 4 is used as a base and the first electrode is arranged horizontally in contact therewith so as to withstand the bonding pressure of the jig tip portion.

A necessary condition for the second electrode 6 is a space where the semiconductor chip is overlaid on the upper surface and a sufficient amount of solder is filled in the overlapping portion so that stress such as pushing pressure or pulling force is not applied to the semiconductor chip. It is to be held in a position and within a size and position range that does not hinder soldering workability.

Explaining in connection with claim 2, the second electrode 6 is a copper plate, and its typical dimensions are 1 mm in thickness and 18 m in width.
m, a protruding length dimension from the inner wall of the resin case frame 4 to the inside of the case is formed to be 30 mm, and a bent portion for forming a step or an inclination is formed at a position of 8 mm from the inner wall to form, for example, an emitter electrode on the upper surface of the semiconductor chip 2. The lower surface of the second electrode 6 is held at a horizontal position higher by 0.2 mm than the layer so that the lower surface of the second electrode 6 comes to the soldering step, and soldering is performed so as to fill the gap of 0.2 mm.

The first electrode 5 is bonded to the cathode electrode layer, for example, on the upper surface of the semiconductor chip 2 with an aluminum thin wire. In this way, the current value, workability, and quality variations are taken into consideration, and either wire bonding or lap joint soldering can be selected and the construction method can be used differently, so quality is stable and reliability is improved. Can be
The improved workability has reduced the product defect rate and made it possible to provide it at low cost.

The second embodiment will be described with reference to FIG. FIG. 2 is a plan view of the second electrode 6. For example, a copper plate has a thickness of 1 mm, a width of 18 mm, and a protrusion of 30 mm from a length of 18 mm, and a hole of 1.2 mm in diameter is provided in a portion of the length of 18 mm. The properness of the quantity can be confirmed, and it became easier to manage the variation in soldering quality.

A third embodiment will be described with reference to FIG. FIG. 3 is a plan view of the second electrode, in which a comb-shaped cut portion is formed in a flat metal plate and soldered to the upper surface of the semiconductor chip. It is now possible to more clearly check the finished state of soldering.

[0015]

According to the present invention, the first electrode and the second electrode are formed on the same terminal fitting, the wire bonding method is used for the first electrode, and the soldering method is used for the second electrode. Since the construction method selected according to the shape and dimensions of the upper surface of the semiconductor chip can be selectively used, the workability is more advantageous by using the construction method which is more advantageous.
Improved reliability such as disconnection. For example, when manufacturing 5 series terminal fittings by size according to the current rank, the molds required to make 10 kinds of fittings in each of the conventional 2 ways can be integrated into 5 kinds, so it is necessary for the molds. Materials can be halved and products can be provided at low cost, which has great industrial value.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a semiconductor device showing a first embodiment according to the present invention.

FIG. 2 is an enlarged view of a main part of a semiconductor device showing a second embodiment according to the present invention.

FIG. 3 is an enlarged view of a main part of a semiconductor device showing a third embodiment according to the present invention.

FIG. 4 is a structural explanatory view of a conventional semiconductor device.

FIG. 5 is a structural explanatory view of a conventional semiconductor device.

[Explanation of symbols]

1 metal base 2 semiconductor chips 3 terminal fittings 4 resin case frame 5 First electrode 6 Second electrode 7 Bonding wire 8 solder 9 holes 10 Comb-shaped electrode notch

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-1-255257 (JP, A) JP-A-10-56096 (JP, A) JP-A-62-202548 (JP, A) JP-A-2000-183249 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21 / 60,23 / 48-23/50 H01L 25 / 07,25 / 18

Claims (4)

(57) [Claims] 1. A semiconductor chip provided on a metal base, a terminal fitting wired and led out from the semiconductor chip, and a resin case frame for fixing the terminal fitting, wherein the metal base and the resin case frame are fixed to each other. In the semiconductor device, one end of the terminal fitting is led out as an external terminal, and the other end projects and is exposed inside the resin case frame to form a flat plate-shaped first electrode as a bonding wire connection surface. As a lap joint for soldering by extending the tip of
Features a structure in which a second electrode is formed and wiring is performed from the first electrode, soldering is performed directly from the second electrode, or two construction methods can be selected with one terminal metal fitting for connecting the semiconductor chip and the terminal metal fitting. Semiconductor device. 2. The semiconductor device according to claim 1, wherein the tip of the first electrode is extended by providing a step or an inclination, and the second electrode is formed on a plane different from that of the first electrode. 3. The semiconductor device according to claim 1, wherein the shape of the second electrode is a flat plate having a hole. 4. The semiconductor device according to claim 1, wherein the second electrode has a comb shape.