JPH06244302A - Injection-molded printed board - Google Patents

Abstract

PURPOSE:To prevent reduction in the workability and bonding reliability of the wire bonding of a semiconductor pair chip to be mounted on an injection- molded printed board. CONSTITUTION:In an injection-molded printed board O, recesses 9a and 9b are provided at the position where the semiconductor chip 3 is to be mounted and at the corresponding position on the rear of the board, and the thickness of the board in the position where the semiconductor chip 3 is to be mounted is made about 2mm or less. As a result, when the semiconductor chip and a conductor pattern are connected by wire bonding on the injection-molded printed board, the heat applied from the rear of the board sufficiently propagates to the semiconductor chip and the conductor pattern in a short time, and thus, reduction in the workability and bonding reliability of the wire bonding can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an injection-molded printed circuit board on which a semiconductor bare chip is mounted.

[0002]

2. Description of the Related Art An example in which a semiconductor bare chip is mounted on a conventional printed board will be described with reference to FIG. FIG. 3A shows an example of mounting on a glass epoxy substrate which is often used as a mounting substrate for a semiconductor bare chip. The glass epoxy substrate 1 is originally a substrate having a uniform thickness, and the semiconductor bare chip 3 is mounted on the glass epoxy substrate 1. A substrate having a thickness of 1.6 mm or less is used. This is because wire bonding must be performed while heating the semiconductor bare chip 3 from the back surface of the substrate, so that heat is applied to the semiconductor bare chip 3.
It has been taken into consideration so that it can be fully transmitted. If the heat from the bonder is difficult to be transferred, it takes a long time to raise the temperature, which lowers the workability, lowers the reached temperature, causes peeling of the bond, and reduces the bonding reliability of the wire bonding. 2a and 2b are conductor patterns provided on the substrate surface, 4 is a die bond paste for fixing the semiconductor bare chip 3 to the conductor pattern 2a, 5 is a bonding wire for connecting the electrode pad of the semiconductor bare chip 3 and the conductor pattern 2b, and 6 is a semiconductor It is a sealing resin that protects the bare chip 3 and the bonding wire 5.

Further, another conventional example is shown in FIG.
This example is for mounting a semiconductor bare chip of a power device that consumes a large amount of power. In the figure, 7 is a metal base substrate such as Al having good heat dissipation, and 8 is an insulating layer such as epoxy resin. Since other configurations are the same as those in FIG. 3A, the same reference numerals are given to the same configurations. In this substrate, for example, after the insulating layer 8 is formed on the base substrate 7,
It is manufactured by bonding a copper foil thereon and removing unnecessary copper foil by etching to form the conductor patterns 2a and 2b. In the case of this substrate, since the base substrate 7 is made of metal and heat is easily transferred to the semiconductor bare chip 3 from the back surface of the substrate, the above-described problems of deterioration in workability and bonding reliability during wire bonding do not occur, but the entire substrate surface It was necessary to provide a metal base substrate over the entire length, which also constrained the conductor pattern design.

On the other hand, FIG. 3C shows a case where a semiconductor bare chip is mounted on an injection-molded printed board. In the figure, 9 is an injection molded printed circuit board, which is usually made of high heat resistant thermoplastic resin such as polyetherimide resin, liquid crystal polymer and polyphenylene sulfide resin.
FIG. 3C shows a portion where the plate thickness of the substrate is large (approximately 2 mm).
2 shows a state in which the semiconductor bare chip 3 is mounted on a portion (exceeding the point). In this case, since the substrate is made of resin and the heat conduction is poor, heat from the rear surface of the substrate is difficult to be transferred to the semiconductor bare chip 3, and the above-described problem at the time of wire bonding occurs. In addition, the same components as those in the conventional example are designated by the same reference numerals. The injection-molded printed circuit board 9 used in this example is, for example, wire-bonded after the injection-molded product is plated with Cu and the unnecessary portions are removed by etching to form the conductor patterns 2a and 2b. It is manufactured by a process of performing necessary Ni and Au plating on the conductor patterns 2a and 2b.

[0005]

As described above, when a semiconductor bare chip is mounted on a conventional injection-molded printed circuit board, if the semiconductor bare chip is mounted on a thick part of the board, the heat applied from the backside of the board is connected to the semiconductor bare chip and it. Since it is difficult to reach the conductive pattern, the workability of wire bonding and the joint reliability are deteriorated.

The present invention has been made in view of the above problems. An object of the present invention is to perform injection molding capable of preventing workability and bonding reliability of wire bonding from being lowered due to insufficient temperature rise of a semiconductor bare chip and a conductor pattern. It is to provide a structure of a printed circuit board.

[0007]

In order to solve the above-mentioned problems, the present invention provides an injection-molded printed circuit board for mounting a semiconductor bare chip, wherein a recess is formed in at least one of the semiconductor bare chip mounting position and the substrate backside position, The board thickness at the semiconductor bare chip mounting position is approximately 2 mm or less.

As another means, in an injection-molded printed circuit board on which a semiconductor bare chip is mounted, a recess is formed at least at the substrate backside position at the semiconductor bare chip mounting position and the substrate backside position, and the substrate at the semiconductor bare chip mounting position is formed. The plate thickness is set to about 2 mm or less, and a good thermal conductor having good thermal conductivity is arranged in the concave portion on the back side of the substrate.

[0009]

In the injection-molded printed circuit board of the present invention, the recesses formed at the semiconductor bare chip mounting position and the substrate back side position locally thin the board thickness at the semiconductor bare chip mounting position, and the wire is bonded from the back side of the substrate for wire bonding. Makes it easier for the applied heat to be transferred to the semiconductor bare chip and conductor pattern.

Further, the good thermal conductor having good thermal conductivity arranged in the recess on the back side of the substrate at the semiconductor bare chip mounting position facilitates the transfer of heat applied from the back side of the substrate for wire bonding to the semiconductor bare chip and the conductor pattern. .

[0011]

FIG. 1 shows an example of the present invention.
As compared with the conventional example of (c), recesses 9a and 9b are formed at the mounting position of the semiconductor bare chip 3 of the injection molded printed circuit board 9 and the position on the back side of the substrate, and the board thickness at the mounting position is approximately 2 mm.
Since the other configurations are the same as those of the conventional example, the description thereof will be omitted by giving the same reference numerals to the same configurations.

The semiconductor bare chip 3 is made of Ag as in the conventional case.
After being mounted in the recess 9a of the injection-molded printed circuit board 9 through the die-bonding paste 4 such as paste, it is connected to the conductor pattern 2b by wire bonding such as Ag wire, and is sealed with resin to protect the semiconductor bare chip 3 and the bonding wire 5. However, at the time of wire bonding, the temperature of the semiconductor bare chip 3 and the conductor pattern 2b rises to the temperature required for wire bonding in a short time by heating from the recess 9b on the back side of the substrate. Also, it does not cause a decrease in joint reliability.

The shapes of the recesses 9a and 9b are not limited to those in the above-described embodiment, but may be changed depending on the size and position of the semiconductor bare chip 3 and the conductor patterns 2a and 2b, the shape of the bonding apparatus, the heating method and the like. Just change it to fit.

FIG. 2 shows a different embodiment, in which a member having good thermal conductivity such as Cu is integrally molded as a good thermal conductor 10 in a recess formed on the rear side of the mounting position of the semiconductor bare chip 3 on the injection molded printed board 9. The same components as those of the conventional example are designated by the same reference numerals.

Also in this example, the board thickness at the mounting position of the semiconductor bare chip 3 is set to about 2 mm or less.
Similar to the example of 1, the problem at the time of wire bonding can be prevented. Further, since the good thermal conductor 10 also has a function of radiating the heat generated from the semiconductor bare chip 3, it is suitable for mounting the semiconductor bare chip 3 of a power device having a large heat generation amount.

The material of the good thermal conductor 10 is not limited to Cu, and materials other than Al and metal can be applied.
Further, in this example, the good thermal conductor 10 is arranged in the recess of the substrate by integral molding, but it may be attached after molding the substrate.

Alternatively, the injection-molded printed circuit board may be constructed as shown in FIG. 1 and another member having a high thermal conductivity may be brought into contact with the concave portion on the back side of the board in a state where the board is incorporated in a device. Good.

[0018]

As described above, when the semiconductor bare chip and the conductor pattern are connected by wire bonding on the injection-molded printed circuit board, the heat applied from the back side of the substrate is sufficiently applied to the semiconductor bare chip and the conductor pattern in a short time. Since it is transmitted, it is possible to prevent the workability of wire bonding and the decrease of the joint reliability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example in which a semiconductor bare chip is mounted using an injection-molded printed board according to the present invention.

FIG. 2 is a cross-sectional view showing another example in which a semiconductor bare chip is mounted using the injection-molded printed board of the present invention.

FIG. 3A is a sectional view showing an example in which a semiconductor bare chip is mounted on a conventional printed circuit board, FIG. 3B is a sectional view showing a different example in which a semiconductor bare chip is mounted on a conventional printed circuit board, and FIG. FIG. 6 is a cross-sectional view showing an example in which a semiconductor bare chip is mounted on a conventional injection-molded printed board.

[Explanation of symbols]

 1 Printed Circuit Boards 2a, 2b Conductor Pattern 3 Semiconductor Bare Chip 4 Die Bond Paste 5 Bonding Wire 6 Sealing Resin 7 Base Board 8 Insulation Layer 9 Injection Molded Printed Circuit Boards 9a, 9b Recess 10 Good Thermal Conductor

Claims (2)

[Claims] 1. In an injection-molded printed circuit board on which a semiconductor bare chip is mounted, a recess is formed in at least one of the semiconductor bare chip mounting position and the substrate backside position, and the board thickness of the semiconductor bare chip mounting position is approximately 2 m.
An injection-molded printed circuit board characterized by having a thickness of m or less. 2. In an injection-molded printed circuit board on which a semiconductor bare chip is mounted, a recess is formed at least at the substrate backside position at the semiconductor bare chip mounting position and the substrate backside position thereof, and the substrate board thickness at the semiconductor bare chip mounting position is substantially equal. An injection-molded printed circuit board having a length of 2 mm or less, and a good thermal conductor having good thermal conductivity being disposed in the recessed portion at the back side of the substrate.