JPH0529763A - Manufacture of multilayer copper clad laminated board - Google Patents

Abstract

PURPOSE:To promote mass production, speed up delivery and reduce cost by clamping a releasability film between prepregs, forming a both sided copper clad laminated board, a circuit pattern on a copper foil on both sides and then removing the film, separating into two single-sided circuit boards and lapping the prepregs and the outer layer copper foil on both sides of the single-sided circuit boards. CONSTITUTION:A release film whose both surfaces are further roughened are inserted between prepregs and heat and pressure-molded. Outwardly, the film looks like a both-sided copper clad laminated board, but in reality, there is available a laminated board laminated by two single-sided copper clad laminated boards in structure. Then, there is formed a circuit pattern 4 which comprises an inner layer circuit 1, a flow stopper 2 and a connector 3 on both-sided copper foil on both-sided copper clad laminated board. Then, the release film is separated, removed and divided into two single-sided circuit boards. The single-sided circuits boards are used as an inner layer board where a prepreg and an outer layer copper foil are laminated in order and heat and pressure-molded so as to obtain a multilayer copper clad laminated board. This construction makes it possible to obtain multilayer copper clad laminated boards efficiently.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer copper clad laminate having an inner layer circuit which does not require high circuit accuracy at low cost and with good workability.

[0003]

2. Description of the Related Art In recent years, with the increasing demand for higher speed and higher density of industrial electric and electronic equipment, the circuit board on which electronic parts are mounted has been made more multi-layered and more accurate. The demand for multi-layered circuit boards can be broadly divided into high-grade type, which pursues high multi-layer and high precision, and general-purpose type of 3 to 4 layers, which is intended to be applied to power supply circuits, ground circuits, electromagnetic wave shield circuits, etc. There are two types, and the latter general-purpose type accounts for most of the demand. In such a general-purpose type, the inner layer circuit does not necessarily have to be highly accurate, but rather mass production, short delivery time, and cost reduction are required.

[0004]

However, among the conventional multi-layer circuit boards, particularly in the three-layer board, the inner layer circuit is formed by using the single-sided copper-clad laminate board.
The number of steps and the cost are twice or more as much as that for one layer of the inner layer circuit in the four-layer board, and there is a problem that mass production, short delivery time, and cost reduction are insufficient.

The present invention has been made to solve the above problems, and provides a method for producing a multi-layer copper-clad laminate, which can sufficiently cope with mass production, quick delivery, and cost reduction. The purpose is to do.

[0006]

[Constitution of the invention]

[0007]

A method for producing a multi-layered copper-clad laminate according to the present invention comprises a release film whose both surfaces are roughened, sandwiched between prepregs, and heated and pressed to form a double-sided copper-clad laminate. After molding, a circuit pattern is formed on each of the copper foils on both sides, and then the obtained double-sided circuit board is separated into two single-sided circuit boards by peeling and removing the release film. It is characterized in that a prepreg and an outer layer copper foil are sequentially laminated on both sides of the plate, and they are heated and pressed to be integrally molded.

As the release film used in the present invention, it is desirable to use a release film having excellent adhesion to the prepreg so as not to be peeled off in the circuit pattern forming step in the double-sided copper clad laminate. In addition, in order not to be attacked by the processing chemicals during the etching and blackening treatment of the copper foil in the circuit pattern forming process, it has excellent chemical resistance and can sufficiently withstand the heating during the blackening treatment. It is desirable that the material has good heat resistance. Examples of the material of the release film which satisfies such requirements include triacetyl cellulose, polymethylpentene, vinyl fluoride, polyester and the like.

Further, it is desirable that such a release film has both surfaces roughened. That is, in the case where both surfaces of the release film are roughened, the rough surface is transferred to the surface of the single-sided circuit board separated by removing this, and the prepreg is further laminated thereon. This is because the adhesion is improved.

In the present invention, in order to form a circuit on a double-sided copper-clad laminate in which such a release film is sandwiched,
After forming a resist layer by laminating a dry resist film on the copper foil on both sides, or by printing a resist ink, exposure-development-etching-blackening treatment (to improve adhesion with prepreg, usually This is performed only for the inner layer circuit).

An example of the circuit board thus obtained (actually, two single-sided circuit boards are laminated, but apparently a double-sided circuit board) is shown in FIG. On both sides of this circuit board,
A circuit pattern 4 (which serves as an inner layer circuit pattern) including an inner layer circuit portion 1, a flow stop portion 2, and a connecting portion 3 connecting these is formed. In addition, in the circuit pattern 4, the flow stop portion 2 keeps the plate thickness as constant as possible and prevents the resin from flowing out of the prepreg when a prepreg or the like is stacked thereon to form a multilayer copper clad laminate. Formed in. Further, the flow stop portion 2 is provided with a reference hole 5 for post-processing such as a drill hole or pattern printing. The size of the finally obtained multilayer circuit board is the part inside the one-dot chain line, which is obtained by removing the flow-stopping part 2 and a part of the connecting part 3 from the entire inner layer circuit pattern.

[0012]

In the present invention, a release film is inserted between prepregs and heat-pressed to form an apparently double-sided copper-clad laminate, and actually two single-sided copper-clad laminates are laminated. A laminated board having the above structure is obtained. Next, the copper foil on both sides of the double-sided copper-clad laminate thus obtained was exposed-developed-
A circuit pattern is formed by a usual method of etching-blackening treatment, but such a circuit is formed more efficiently in a double-sided copper-clad laminate than in a single-sided copper-clad laminate. Therefore, the circuit board can be obtained with high productivity. After that, the release film is peeled off from the obtained circuit board to separate it into two single-sided circuit boards, and then the single-sided circuit board is used as an inner layer board, and a prepreg and an outer layer copper foil are sequentially formed on both surfaces thereof. By laminating and heat-pressing, a multilayer copper clad laminate can be obtained in a short time and at low cost. Further, a circuit is formed on each of the outer copper foils of the thus obtained multilayer copper clad laminate by a conventional method to obtain a multilayer circuit board (three-layer board).

[0013]

EXAMPLES Examples of the present invention will be described below.

Example 1 First, as an inner layer circuit pattern, an inner layer circuit portion having a large number of clearance holes and thermal lands, a flow stop portion provided with a reference hole and a test coupon for post-processing, and a connection for connecting them. And a pattern having a part were selected to prepare a master film having such a pattern processed and formed. In addition, a release film (made of triacetyl cellulose) with roughened surfaces is sandwiched between 8 glass epoxy prepregs with a resin amount of 42% by weight, a gel time of 120 seconds, and a thickness of 200 μm, and hot pressed. A double-sided copper-clad laminate was molded by heating and pressurizing the same. Then, on the copper foil on the surface of the obtained double-sided copper-clad laminate, each is laminated with a normal dry resist film, and the master film is used for exposure, development, and etching, and then the resist film is peeled off. A double-sided circuit board was obtained. Then, the release film was peeled off from the double-sided circuit board and separated into two single-sided circuit boards. One piece of the single-sided circuit board obtained after that was put in a resin amount of 42% by weight and a gel time of 120.
Sec., Sandwiched between 4 glass epoxy prepregs with a thickness of 200 μm, and placing an 18 μm thick outer layer of electrolytic copper foil on both sides of the prepreg, and then heating for 90 minutes at 175 ° C and a pressure of 4-40 Kg / cm ^2. It was pressed and integrally molded to obtain a three-layer copper-clad laminate.

Comparative Example 1 In Example 1, a double-sided copper-clad laminate was produced in the same manner by using a release film which was smooth on both sides and was not roughened, and after forming a circuit pattern, a prepreg and an outer-layer copper foil were formed. Was placed and heat-pressed to obtain a 3-layer copper-clad laminate.

Comparative Example 2 According to a conventional method for producing a multilayer copper-clad laminate, a glass epoxy single-sided copper-clad laminate was first molded, and a circuit was formed in the same manner as in Example 1 to obtain a single-sided circuit board. .. Then
Using this single-sided circuit board, a copper clad laminate having three layers was obtained in the same manner as in Example 1.

Next, the multilayer copper clad laminates produced in Example 1, Comparative Example 1 and Comparative Example 1 were subjected to the following characteristic evaluation tests for moisture and heat resistance, warpage, workability, and cost.

Humidity and heat resistance test: After the outer layer copper foil of the multilayer copper clad laminate is removed by etching, the sample is cut into 50 × 50 mm. These samples were boiled for 2, 4, and 6 hours respectively, and 1 and 2 hours PCT (120 degrees, 2
260 degrees x 12 each
After floating in a solder bath for 0 seconds, its appearance was evaluated. The evaluation levels are as follows. A ... No change. B: Slight measling occurred. C ... Measling occurs. D: Delamination with a diameter of 5 mm or less occurred. E: Delamination exceeding 5 mm in diameter occurred.

Warpage: A multilayer copper clad laminate is cut into a sample of 330 × 330 mm. This sample was (1) normal state, (2) outer layer copper foil was removed by etching and air-dried, (3) (2)
For each of the states heated at 130 ° C. for 1 hour, they were placed flat and the magnitude of warpage was measured, and the maximum warpage was evaluated.

Workability: Ease of work process and efficiency were evaluated.

Cost: Manufacturing cost was comparatively evaluated.

The results are shown in the table below.

[0023]

[0024]

As is apparent from the above description, according to the manufacturing method of the present invention, a multilayer copper clad laminate having good heat and humidity resistance and less warpage can be efficiently obtained, and mass production can be achieved. It is possible to fully meet the demands for shorter delivery times and lower costs.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a double-sided circuit board on which a circuit pattern is formed.

[Explanation of symbols]

 1 ………… Inner layer circuit section 2 ………… Flow stop section 3 ………… Connecting section 5 ………… Reference hole

Claims (1)

Claims: 1. A release film having roughened surfaces is sandwiched between prepregs, heated and pressed to form a double-sided copper-clad laminate, and a circuit is formed on each of the copper foils on both sides. After forming a pattern and then separating the obtained double-sided circuit board into two single-sided circuit boards by peeling and removing the release film, a prepreg and an outer layer copper foil are formed on both surfaces of the single-sided circuit board. Are sequentially laminated, and heated and pressed to be integrally molded, thereby producing a multilayer copper-clad laminate.