JPS61161795A - Rigid type multilayer 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] [Field of Industrial Application] The present invention relates to a printed circuit board on which electronic components are mounted, and in particular to a litho-type multilayer printed circuit board that is excellent in economic efficiency and enables high-density mounting. Regarding.

[Conventional technology and its problems]

Conventionally, printed circuit boards have been made by firmly adhering Cu foil to a paper phenol or glass epoxy board and etching it to form a predetermined circuit, or by laminating multiple layers of these types to create a high-density printed circuit board. converted is used.

Such printed circuit boards can be mass-produced and are relatively economical. However, since the substrate is made of organic resin, it has poor heat conductivity and heat dissipation. For this reason, printed circuit boards on which components are mounted using high-density double-sided mounting often reach the permissible limit in terms of thermal management. especially,
This is an important problem to be solved in the case of power supply circuits and armature electronics circuits that use relatively large amounts of power.

Therefore, printed circuit boards are used whose substrates are made of ceramics such as alumina, which have high heat conductivity. However, such a ceramic circuit board is two to three times more expensive to manufacture than the above-mentioned printed circuit board using resin. Moreover, there is a problem that a special manufacturing process is required.

Further, in the case of a ceramic circuit board, dimensional changes occur during heating and firing, and deformation at that time cannot be avoided, so there are significant restrictions on the shape of the board. Therefore, a printed circuit board was developed in which Cu foil was adhered to an aluminum plate and etched. However, since this printed circuit board is a single-sided printed circuit, there is a problem that high-density mounting cannot be achieved sufficiently.

The present invention has been made in view of these points, and has the objective of improving heat transfer characteristics, enabling high-density packaging, and
The present invention provides a printed circuit board that enables mass production and reduces manufacturing costs.

[Means to solve the problem]

The present invention is a linot type multilayer printed circuit board in which a flexible printed circuit with circuits formed on both sides is mounted on a metal substrate via an insulating layer.

The figure is an explanatory diagram showing a schematic configuration of the present invention.

In the figure, 1 is a metal substrate made of A4 Cu, E's, or the like. A flexible printed circuit 3 is bonded onto the metal substrate 1 with an insulating layer 2 interposed therebetween. The flexible printed circuit 3 includes a film 4 made of heat-resistant resin such as polyimide resin, and conductor circuits 5 formed on both sides of the film 4 using copper foil or the like, and conductor circuits 5 formed on both sides of the through holes 6 formed therein. The circuits on both sides of the film are integrated. The thickness of the film 4 is set within the range of 0.01 to 0.05 . The reason why the thin film 4 is made as described above is to improve heat conductivity. Manufacture of flexible circuit 3.

Usually, the Cuff 11 is attached to both sides of the film 4, patterned by etching, and through holes 6 are formed, followed by chemical plating and mechanical caulking. The thickness of this Cu foil is 18μ
, about 35μ are used. Further, flexible circuits are manufactured by a so-called continuous coil-to-coil process.

As the material of the insulating layer 2, in addition to polyimide resin, polyamide resin, polyurethane resin, and phenol resin may be used. In addition, in order to improve heat conductivity, K, insulating layer 2
Ceramic powders such as K At203, TiO□, BN, BeV, AtN, etc. may be blended in an amount of 5 to 40% by weight. The metal plate is the same size or larger than the circuit board.

[Effect]

According to the litho-type multilayer printed circuit board of the present invention, the pre-formed flexible printed circuit 3 is attached to the metal substrate 1.
Since the metal substrate 1 is integrally attached with an insulating layer 2 interposed therebetween, unlike a conventional so-called metal paste substrate, the metal substrate 1 is protected from corrosion during machining, ching treatment, resist stripping treatment, bite hole plating treatment, etc. No exposure to aqueous solutions.

Therefore, there is no need to form a protective film on the metal substrate 1 against such a corrosive aqueous solution, and it is possible to improve heat dissipation, simplify the manufacturing process, and reduce manufacturing costs. Also, conductor circuits 5 are provided on both sides of the film 4.
By forming the film 4, high-density packaging can be achieved, and the film 4 can be made extremely thin to improve heat transfer characteristics. The metal plate must be the same size or larger than the circuit section.

In addition to being able to exhibit sufficient heat dissipation, the flexible circuit, which has been made as thin as possible for heat conduction, is sufficiently reinforced, making it possible to mount various components.

Bend any metal parts that protrude outward from the circuit.

The board can be finished into a desired shape by any processing such as drilling, and the board can be attached to a device for fixation or used as at least a part of the structure of the device (such as a chassis).

〔Effect of the invention〕

The present invention uses a metal substrate and a thin film to improve heat transfer characteristics and heat dissipation, enables high-density packaging, and facilitates mass production with a simplified manufacturing process, reducing manufacturing costs. It is something that can be done.

〔Example〕

Examples of the present invention will be described below.

Example 1 A 35 μm thick Cu foil is pasted on both sides of a 25 μm thick film 40 made of polyimide resin and etched to form a conductor circuit 5 in a predetermined pattern. :W-thread flexible printed circuit 3 was manufactured. The size of this flexible printed circuit 3 was 400×500 mst. This is placed on an aluminum substrate 1 with a thickness of 1.2 cm.
They were bonded together through an insulating layer 2 made of Nixy resin containing 15% by weight of N. After that, change this to 200X160
A heat-dissipating two-layer printed circuit board was obtained by dividing the substrate into pieces having a size of m.

It has been experimentally confirmed that the printed circuit board is extremely easy to manufacture and has excellent heat dissipation and heat transfer properties. Also,
It was found that the packaging density was comparable to that of conventional ceramic substrates, and that manufacturing costs could be reduced by approximately 50 inches.

Example 2 A 2-lexiple printed circuit was manufactured in the same manner as in Example 1 using a polyimide resin film 4 having a thickness of 50 μm. The size of this flexible printed circuit is 450
It was 500 mg.

This is a metal substrate 1 made of silicon steel with a thickness of 1.5+ms.
On top of this, an insulating layer 2 made of an epoxy resin 1 containing 12% by weight of TfO□ was bonded to the substrate. After that, change this to 1
A printed circuit board having both magnetic shielding and heat dissipation properties was obtained by dividing it into 45×160+m++ sizes. This printed circuit board was easy to manufacture, and the mounting density was about 80% higher than that of conventional single-layer circuits made of silicon steel plates, and the manufacturing cost was only about 20% higher.

[Brief explanation of drawings]

The figure is a sectional view showing a schematic configuration of the present invention. DESCRIPTION OF SYMBOLS 1... Metal substrate, 2... Insulating layer, 3... Flexible printed circuit, 4... Film, 5... Conductor circuit, 6... Through hole.

Claims (1)

[Claims] 1. A rigid multilayer printed circuit board, characterized in that a flexible printed circuit with circuits formed on both sides is bonded to a metal substrate of the same size or larger than the flexible printed circuit via an insulating layer.