JPS58184786A - Metal core printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in the electrical connection between a core and a conductor circuit.

In a metal core printed wiring board, electrically connecting a part of the conductor circuit and the metal core is extremely effective when the metal core itself is at ground potential or when used as part of an electric circuit. In such cases, the conventional method, for example when using an aluminum plate as a metal core, is to remove the insulating layer on the surface with an end mill and then wire bond the exposed aluminum surface with aluminum wire. It has been adopted.

However, with this method, the stability of the wire bond tends to be insufficient due to the step between the conductor circuit surface and the recess made by the end mill, and the wire bonding wire generally has a small wire diameter, so the metal core printed wiring board cannot be used. It has a drawback that it is difficult to apply it to large current circuits such as Bawano hybrid ICs, which are often used.

Furthermore, since the insulating layer is removed using an end mill, the surrounding insulating layer is likely to peel off, which may adversely affect the surrounding circuitry. Furthermore, since the metal used as the metal core is not necessarily a metal with which aluminum wire can be easily bonded, this type of conventional method also has the disadvantage of lacking in versatility.

The present invention was made to solve the above-mentioned drawbacks, and
The purpose of this is to ensure electrical connection between the conductor circuit and the metal core on a metal core printed wiring board using a simple and versatile connection means, and to ensure stable electrical connection even when the current carrying capacity is large. The object of the present invention is to provide a metal core printed wiring board obtained.

The present invention provides a metal core printed wiring board in which a conductor circuit is provided on a metal core via an insulating layer, and the metal core facing the conductor through hole is soldered onto the same type of metal as the metal core. A chip made of a metallized metal obtained by metallizing a metal that can be soldered is bonded to the metals of the same type, and the solderable metal of the chip and the conductive circuit are soldered. It is a metal core printed wiring board.

Hereinafter, the present invention will be explained by examples using the drawings. FIG. 1 is a plan view showing an example of the metal core printed wiring board of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA' shown in FIG.

In the figure, 1 is a metal core made of aluminum, 2 is an insulating layer made of polyimide, polyester, etc.
3 is a conductor made of copper, and 4 is an overlay (coverlay or resist ink) applied thereon.A conductor circuit is formed on the conductor 3 by photoetching or the like.

A land 5 is electrically connected to the metal core 1.

For this connection, a through hole 6 passing through the conductor 3 and the insulating layer 2 is provided at the location of the land 5 to be connected to the metal core l. A chip 7 made of a metallized metal is bonded onto the metal core 1 facing the through hole 6. This metallized metal chip is made by coating a solderable metal (e.g., copper, tin, etc.) 9 on a metal (e.g., aluminum) 8 of the same type as metal, Q; l, using metallization. , to join the chip 7 made of these to the metal core 1, a metal 8 of the same type as the metal core l is used.
and the metal core l, and join them using, for example, an ultrasonic welder. This joining can be easily and reliably performed since they are made of the same material.

As a metallizing metal for chips, for example, a copperizing sheet (trade name of Aichi Steel Corporation) is used, which is produced by coating aluminum with chlorinated steel and heating it to form a compound of AI and Cu on the aluminum. It is coated with copper, and is coated with various types of electroplating such as copper and nickel (eg, 15 to 30 μm thick).

Next, the land 5 is soldered to the solderable metal 9 on the opposite side of the metal core I of the chip 7. In this case, since both are metals that are easy to solder (for example, copper), soldering is extremely easy and reliable.

Note that the metal core printed wiring board used in the present invention, in which a conductor circuit is provided on a metal core via an insulating layer, has a conductor circuit formed on a board with a conductor foil bonded to an insulating film, and if necessary, A printed wiring board (for example, a flexible printed wiring board) coated with coverlay or resist ink is prepared, and a metal core is superimposed and laminated on the back surface of this board. in this case,
The aforementioned through holes 6 are provided in the printed wiring board before laminating the printed wiring board and the metal core. Therefore, drilling the through hole 6 is easy.

Conventionally, there is a method of bonding copper on aluminum using solder for aluminum. This solder is Cd-Zn-based or 5n-Zn-based solder that does not contain PB to avoid intergranular corrosion between AI and Pb, but the method for soldering with aluminum involves melting the solder on the aluminum. There is a problem that if you don't brush your hair after cleaning, the stone gate will be bad. Therefore, for example, if you try to solder directly to an aluminum core, it will be difficult as described above, but in the present invention,
Bonding is easy because the aluminum side of a chip made of aluminum coated with copper is bonded onto an aluminum core using an ultrasonic welder, etc., and then the mesh side of the chip and the copper of the conductor circuit (copper) are manually soldered. Since soldering is carried out using a flow solder or the like, soldering can be carried out very easily using 5n-Pb solder.

As a result, the present invention enables the electrical connection between the metal core and the conductor circuit of the printed wiring board to be made by an easy bonding method and soldering method, and there is no problem of contact or intergranular corrosion. This has the effect of reliably maintaining good physical and mechanical connections.

Example: As shown in Figures 1 and 2, an insulating film (e.g., 25 μm thick) made of polyimide, polyester, etc. is coated or laminated with an adhesive, and then a copper foil (e.g., 35 μm thick) is coated with an adhesive. A conductive circuit was formed from the applied material, and O.--lay 4 (coverlay or resist ink) was applied to the necessary portions of the circuit to create a flexible printed wiring board.

Apply adhesive (e.g., thickness 10 to 50 μm) to the back side,
Thereafter, a through hole 6 was drilled using a drill or the like, and the through hole 6 was superimposed on pure aluminum (eg, 0.8 fl thick) and laminated with adhesive under heat and pressure to create a metal core printed wiring board.

A copper rise sheet (copper clad aluminum, Aichi Steel) is placed on the aluminum facing the through hole 6 of this wiring board.
Product name) chip 7 (e.g. thickness 0.1~03mm, diameter 0
5-3. Place Q*m) on aluminum with g side down,
After joining the Al-Al surfaces with an ultrasonic welder, the land 5 and the copper 7 of the chip 7 are connected with 6.4 solder (Pb 60
%, 5n4096) in one bath of 70-solder to create a metal core printed wiring board according to the present invention.

The insulating film used has a thickness of 12 to 300 μm, the copper foil has a thickness of 5 to 300 μm, and the adhesive used includes thermosetting urethane, epoxy, and hot melt film (Dumilan C-2280 manufactured by Mitsui Polychem). irradiated and crosslinked hot melt films are used.

A hot melt film is a film that is melted by heating and acts as an adhesive, and is mainly composed of a polyolefin containing an acetoquine group, a carphokyfur group, and a hydroxyl group.

Although a plastic film was used as the insulating film in the above embodiments, the present invention may also use other insulating films, such as glass cloth impregnated with an adhesive (prepreg).

As described above, the present invention provides a through hole in a metal core printed wiring board at a location where the conductor circuit is to be connected to the metal core, and provides the metal core on the metal core. A chip made of a metallized metal that is metallized with a solderable metal on the same type of metal is bonded to the same type of metal, so the same type of metals are bonded together using, for example, an ultrasonic welder. Therefore, the soldering on the opposite side of the chip is made by soldering the conductive circuit to a metal that can be easily joined and a reliable electrical and mechanical connection is obtained, and therefore, it is not aluminum. Soldering involves soldering two metals together, so S n
-Pb thread solder (for example, 6,4 solder) can be used, and there are advantages in that soldering is easy, there is no problem of contact or intergranular corrosion, and reliable electrical and mechanical connections can be obtained.

Further, the present invention provides a versatile connection means that allows easy electrical connection between the conductor circuit and the metal core, since it is sufficient to simply provide the through hole and insert the chip made of the metallized metal therein for connection. This method has the advantage that wood production can be carried out more reliably, making it easier to produce wood.

Furthermore, in the metal core printed wiring circuit of the present invention, a chip with a larger cross-sectional area is bonded and soldered to the connection part between the metal core and the conductor circuit than in conventional aluminum wire bonding, so the current carrying capacity of, for example, a power hybrid IC is increased. This has the advantage that stable electrical connection can be obtained even when the current is large.

[Brief explanation of drawings]

Figure 1 shows an example of the metal core printed wiring board of the present invention S. 1
．． : FIG. 2 is a plan view showing the AA' cross section shown in FIG. 1. l...metal core, 2...insulating layer, 3...conductor, 4...
Overlay, 5...land, 6.through hole, 7...
Chip, 8. Metal of the same type as the metal core, 9. Metal that can be soldered.

Claims (6)

[Claims] (1) In a metal-core printed wiring board in which a conductor circuit is provided on a metal core via an insulating layer, the conductor circuit and the insulating layer are penetrated at the locations where the conductor circuit and the metal core are to be connected. A through hole is provided, and on the metal core facing the through hole, a chip made of a metallized metal obtained by metallizing a metal that can be soldered onto the same type of metal as the metal core is bonded to the same type of metal. A metal-core printed wiring board characterized in that the solderable metal of the chip and the conductive circuit are soldered. (2) The metal core printed wiring board according to claim 11, wherein the metal core printed wiring board is made by bonding a metal core and a flexible printed wiring board, and the metal core is made of aluminum. (3) A flexible printed wiring board is a flexible printed wiring board in which a film made of polyimide or polyester is coated or laminated with an adhesive, a copper foil is applied on top, a conductor circuit is formed, and a coverlay or resist ink is applied on the conductor. The metal-core printed wiring board according to claim (2), which is a printed wiring board with a magnetic core. (4) A flexible printed wiring board is a flexible printed wiring board on which glass cloth is impregnated with an adhesive (referred to as Bribrag), copper foil is applied to form a conductor circuit, or a coverlay or resist ink is further applied on the conductor. The metal-core printed wiring board according to claim (2), which is a printed wiring board with a magnetic core. (5) The flexible printed wiring board is a flexible printed wiring in which a copper foil is applied on a hot melt film to form a conductor circuit, or a film or resist ink is further applied on the conductor. Claim No. (2) which is a plate
Metal core printed wiring board as described in Section 1. (6) Claim No. (+) in which the metallized metal is made by metallizing copper on aluminum and applying electrical steel plating to a thickness of 15 to 30 μm thereon.
Paragraph, Paragraph (2), Paragraph (8), Paragraph (4) or Paragraph (5)
Metal core printed wiring board as described in Section 1.