JPS63302530A - Circuit board for large current and hybrid integrated circuit thereof - Google Patents

Abstract

PURPOSE:To prevent the concentration of currents according to the little dispersion of partial wall thickness, to stabilize quality as a hybrid integrated circuit for high power, to simplify the manufacturing process of the circuit and to reduce manufacturing cost by mounting solder to a copper circuit pattern section through which large currents flow. CONSTITUTION:Layers consisting of at least aluminum foil and copper foil are laminated onto a good thermal conductive insulating layer 5 on metallic substrates 1 to respectively form circuits, and solder 10 is set up to sections as the large current circuits of the copper circuits 1. The copper foil sections 1 as lower layers consisting of dissimilar metallic composite foil and aluminum foil sections functioning as aluminum bonding posts 3 as upper layers are laminated onto a base metal 6. Circuits composed of eutectic solder 10 are shaped to the sections, through which large currents flow, in the copper foil sections 1. Heat spreaders 2, etc., on which power transistors 7 are placed are loaded with the eutectic solder 10. These power transistors 7, etc., are connected to the aluminum bonding posts 3 by aluminum wires 9, thus forming the circuits.

Description

[Detailed Description of the Invention] (Field of Industrial Application) Does the present invention apply solder locally to copper circuit patterns? The present invention relates to a wire bondable large current circuit board of a power module, typified by an inverter, which is provided with a formed circuit to form a circuit portion that requires large current, and a hybrid integrated circuit thereof.

(Prior technology) Ceramic substrates have traditionally been widely used as hybrid integrated circuit boards for power modules, but since the circuits are formed using precious metal paste, the sheet resistance is large, and the large size of power modules in recent years has It has become unsuitable for electric current. Therefore, in the past, a thin metal plate such as steel was soldered to the circuit to cope with this increase in current. Alternatively, a metal plate with a circuit in which both aluminum and steel metals are exposed and a highly thermally conductive resin is used as an insulating layer can be used as an alternative substrate.
A new board was developed (Japanese Unexamined Patent Publication No. 58-48432).
.

This board uses a part of the circuit with exposed copper to form a circuit by soldering, such as connecting a heat sink or an external relay, and a part of the circuit with exposed aluminum to connect a semiconductor bare chisel to ultrasonographic vibration aluminum. It is designed to perform wire bong 2-ing.

In addition, by applying thick plating to the exposed parts of the aluminum and copper circuit patterns, Taisei Ryutsu Co., Ltd.
There is a high-power hybrid integrated circuit provided with a component circuit, a semiconductor, and a heating element (Japanese Patent Laid-Open No. 62-2587).

However, this method tends to cause variations in the wall thickness of the 7t plating, which takes a long plating time, and it is not possible to achieve a uniform thickness of copper plated in circuit parts that require large currents. The drawback was that the quality of the circuit lacked stability.

(Problems to be Solved by the Invention) The present invention solves these drawbacks, and has the advantage of providing a large current circuit by providing solder on the copper circuit pattern portion where large currents flow. Because the circuit has little variation in current, there is no current concentration, and the quality as a high-power hybrid integrated circuit is stable.Furthermore, the circuit is wire-wrappable, which reduces the circuit manufacturing process and reduces manufacturing costs. The present invention provides a reused circuit board and its hybrid integrated circuit.

(Means for Solving the Problems) That is, the present invention has the following features: 1. A circuit is formed by laminating layers each consisting of at least aluminum foil and copper foil via an insulating layer with good thermal conductivity on a metal substrate; A large current circuit board 2 characterized in that solder is provided at a portion of the copper circuit that will become a large current circuit, and a high thermally conductive insulating layer on a metal substrate is provided with solder at least at an aluminum circuit and a portion that will become a Taisei diversion circuit. A hybrid integrated circuit for large current, characterized in that a semiconductor is arranged on a circuit board formed with a copper circuit provided with a copper circuit, and the semiconductor and an aluminum circuit are connected with an aluminum wire, and 6. Good heat resistance on a metal substrate. A circuit board in which a semiconductor is arranged on a circuit board formed of a conductive insulating layer formed with a copper circuit with solder provided at least in the aluminum circuit and the portion that will become the Taisei diversion circuit, and the semiconductor and the aluminum circuit are connected with an aluminum wire. A hybrid integrated circuit for large current, characterized in that an external lead terminal is connected and the front and circuit board are sealed with a delta-shaped silicone resin and an epoxy resin composition.

The present invention will be explained in detail below.

, g1 (a+, (t)) and (C) are a plan view and an 1iffJ diagram of an embodiment representing a hybrid integrated circuit of the present invention. Fig. 1 (+) shows that on the base metal 6, through the insulating layer 5, there is a copper conductor part 1 made of composite foil of different metals, the upper layer is aluminum, and the aluminum tunneling post 3 is made of aluminum. Laminated. Further, a circuit made of eutectic solder 10 is formed in a portion of the shoulder foil portion 10 through which a large current flows. Also, this eutectic solder 10 has an elipower transistor 1
Heat Szoretsuda on which was placed.

2 and other heating elements such as transistors and FKTs.

An IC or the like, specifically a diode 8, is mounted thereon. Further, these power transistors 7 and diodes 8 are connected to an aluminum bonding post 3 by an aluminum wire 9 and rotated, and a copper dissipating part 1 is formed on the upper layer thereof, and the other parts are as shown in FIG. (kl).

Next, in FIG. 2, after connecting the external lead terminal 11 at the external lead terminal soldering part 4 of the circuit 119(b), the circuit is covered with a package 12, and the layer above the insulating layer 5 is connected to the upper end of the package 12. 3 is a cross-sectional view of a circuit sealed with a delta-shaped silicone resin 13 and an epoxy 7 resin composition 14. FIG. Note that the circuit shown in FIG. 2 performs the same operation as the circuit shown in FIG. 1 (C).

The base metal plate used in the present invention (c) is made of aluminum, copper, iron, or an alloy thereof, which has good thermal conductivity.The insulating layer 7, which has good thermal conductivity and flexibility, is made of alumina, beryllia, tron nitride, etc. , thermosetting resins containing good thermal conductivity inorganic fillers such as magnesia, silica, and aluminum nitride, for example, 60wt.
0 pm or more is necessary.

Next, there are two ways to form a circuit in which the metals of both aluminum foil and steel foil are exposed through an insulating layer. A circuit is formed by etching a substrate on which a foil made of aluminum or aluminum foil plated with copper via zinc or nickel is laminated onto an insulator.

Furthermore, the purpose of the part of the hybrid integrated circuit of the present invention that becomes a large current circuit can be achieved by forming solder on copper foil, and the thickness of the solder can be freely changed according to the large current carrying capacity. Can be done.

The method for forming solder on the AM may be either a method of dipping the circuit board in a solder bath or a method of stamping creamy solder on the required portions of the fl eyebrows and heating and reflowing the solder. The thickness of the solder is not particularly limited, but is more than 65 μm, preferably 45 μm to 1500 μm, and more preferably 50 μm to 600 μm. If the wall thickness is less than 65 μm, a large current carrying capacity cannot be obtained, and although there is no particular upper limit, the upper limit for a normal hybrid integrated circuit is about 1500 μm.

Next, the gel-like silicone resin for sealing the circuit may be, for example, either a silicone resin alone or a filler-containing silicone resin having good thermal conductivity. Furthermore, the epoxy resin and composition are not limited in any way as long as they are moisture resistant and have low stress.

In other words, the substrate used in the hybrid integrated circuit of the present invention is a circuit board in which both aluminum and thick steel foil metals are exposed, and there is a circuit with solder formed on the exposed copper foil where a large current flows. It has sufficient current capacity and can flow large currents. Furthermore, since the part that fixes the heating element is also made of thick solder, it can also be used as a heat solder by soldering the heating element.

In other cases, the heat generation of the heating element (power element), the size, and the thermal conductivity of the substrate are issues, and therefore a metal substrate having an insulating layer with good thermal conductivity is necessary for the high power hybrid integrated circuit according to the present invention. becomes.

(Example) This will be explained in detail below using examples.

Example 1 As shown in FIGS. 4(a) and 4(b), the substrate was composed of a dissimilar metal composite foil consisting of a 10 μm steel foil and a 10 μm aluminum foil on a base metal plate 6 with an insulating layer 5 interposed therebetween. Furthermore, eutectic solder 10 with a thickness of 120 μm is formed in the large current circuit portion. Next, using this board, screen printing (solder paste was printed from the IC) on the parts that required soldering (terminal attachment areas, power transistor and diode attachment areas).Next, 8 x 8 x 002ttr
6 x power transistors and 1.5 x L5 x
Six O.2 current diodes were placed at the locations shown in Figure 1 and soldered through a solder reflow oven.

Next, using a thick aluminum wire having a diameter of 400 .mu.m, wire bonding was performed from this power transistor to the aluminum Zenr indebost using the ultrasonic method. Similarly, I wire-bonded the diode from the power transistor.

Next, after soldering the 14 external lead terminals, the package was placed over the circuit, and silicone resin was injected until it covered the aluminum wires and power transistors as shown in Figure 2, and was cured to form a del-shape.

Thereafter, two sets of epoxy resins were injected with an acid compound from above and cured.

By going through the above steps, a high-power power module (inverter) for controlling a motor was completed, having the electric circuit shown in FIG. This inverter is collector insulated, so installation is easy and the allowable current can be 3OA.

Example 2 As shown in FIG. 4(C), aluminum foil was used as an insulation layer 5.
A large one-power module (inverter) for motor control was obtained by carrying out the same operation as in Example 1, except that the thickness of the eutectic solder was 150 μm. This inverter was able to provide an allowable current of 4OA.

Example 6 In the circuit board shown in j44 (a) and (kl), the insulated metal board was composed of a 10 μm steel foil and a 40 μm aluminum foil, in which the thick eutectic solder 10 was not formed in the large current circuit part. was used.

First, solder paste was printed on the large part of this board by screen printing on the circuit part and the parts where soldering was required (power transistor and diode mounting part) on the large part of this board. Next, six power transistors of 8 x 8 x 0-2 gm and six diodes of 1.5 x 1.5 x O, 2 shoulder thickness were placed at the locations shown in Figure 1 and soldered through a solder reflow oven. The thickness of the large current circuit portion of the solder paste was 150 μm after solder reflow.

Wire bonding with thick aluminum wires, soldering of external lead terminals, and packaging were performed in the same manner as in Example 1, except that the substrate on which this semiconductor was mounted was used.
An inverter having the electric circuit shown in FIG. 6 was obtained.

This inverter was able to provide an allowable current of 4OA.

(Comparative example) Using the same board as in the example except that the 'A foil in Fig. 4 was 10 μm and no large current circuit was formed by soldering, a third
The inverter shown in the figure was manufactured.

First, use the same power transistor as in the example, 16×16
It was soldered to a 0-8m copper heat solder using high-temperature solder. This thing? As in the example, a solder paste was placed on a screen-printed board, and the solder was reflowed and soldered together with the diode.

The subsequent steps were carried out in the same manner as in the examples to obtain a packaged finished product. Since this inverter had a thin steel foil thickness of 10 μm, the allowable current was 10 A or less.

(Effects of the Invention) As described above, the present invention has an insulated metal substrate having a circuit pattern in which solder is formed in the 1liily'ffi portion where a large current flows on the aluminum and copper circuit pattern. It is a circuit connected with a wire, so there is no need to reinforce the circuit with a thin metal plate on the ceramic board so that a large tlJ current can flow. (2) When solder is used as a heat spreader, it is advantageous to have close contact with the solder circuit on the board. (3) Since there is an aluminum wire and a tF ring post, it is possible to connect the semiconductor wire with the aluminum wire with good reliability. In particular, thick aluminum wire with a diameter of several hundred μm is indispensable for connecting semiconductor devices such as power transistors that flow large currents, and this thick aluminum wire has the advantage of being able to be wire bonded.

Furthermore, using a metal substrate having an insulating layer with good thermal conductivity = 9 (4) The thermal conductivity is better than when using a conventional ceramic substrate, which is advantageous for increasing the power module Q, Chiru. Moreover, (5) in a power module using a ceramic substrate, the base metal, such as a nickel-plated steel plate, must be bonded to the ceramic substrate by soldering or the like because the ceramic is easily broken; however, in the case of a metal substrate, the base metal is As shown in the figure, since it is placed at the bottom of the package, it has the advantage that there is no need to place a new base metal.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (C) are a plan view and a sectional view of a high-power hybrid integrated circuit of the present invention, and FIG. 2 is an integrated circuit in which the integrated circuit of FIG. 1 is sealed with resin. represents a cross-sectional view of Further, the fifth t'iU is an electric circuit diagram. Next, FIGS. 4(a), (b), and (C) are a plan view and a sectional view showing the board before mounting. Code 1... Steel foil part, 2... Heatsolder, 3
... Aluminum mounting post, 4... External lead Y terminal soldering part, 5... Insulating layer, 6... Base metal plate, 7... Power transistor, 8... Diode, 9 ...Aluminum wire, f-ya, 10...
Sympathetic solder, 11... External IJ -y terminal, 12...
Package, 13... Building-shaped silicone resin, resin, 14
... Epoxy sugar beet composition patent applicant: Denki Kagaku Kogyo Co., Ltd. Ki3A Paper 4 Raku (a)

Claims (3)

[Claims] (1) Layers consisting of at least aluminum foil and copper foil are laminated via a good thermally conductive insulating layer on a metal substrate to form a circuit, respectively, and solder is provided at a portion of the copper circuit that will become a high current circuit. A circuit board for large currents that is characterized by: (2) A semiconductor is placed on a circuit board formed by forming at least an aluminum circuit and a copper circuit with solder in a portion that will become a large current circuit on a good thermally conductive insulating layer on a metal substrate, and the semiconductor and the aluminum circuit are arranged on a circuit board. A high current hybrid integrated circuit characterized by connecting the two with an aluminum wire. (3) A semiconductor is placed on a circuit board formed by forming at least an aluminum circuit and a copper circuit with solder in a portion that will become a large current circuit on a good thermally conductive insulating layer on a metal substrate, and the semiconductor and the aluminum circuit are arranged on a circuit board. 1. A hybrid integrated circuit for large current, characterized in that an external lead terminal is connected to a circuit board which is connected with an aluminum wire, and the circuit board is sealed with a gel-like silicone resin and an epoxy resin composition.