JPS5852358B2 - Manufacturing method for double-sided flat circuit board - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improved method for manufacturing double-sided planar circuit boards.

Conventionally, double-sided flat circuit boards used for sliding parts of various electronic devices have been manufactured as follows.

That is, as shown in FIG. 1, single-sided circuit boards 1 and 1' obtained by printing, etching, plating, etc. in a conventional manner on a single-sided metal foil-clad laminate are used, and the single-sided circuit boards 1°1' The circuit is placed on the surface, and a predetermined number of prepregs 2 are interposed and laminated and molded.

During lamination molding, it is necessary to align the circuits on both sides, and as a means to do so, holes 3 are drilled in the single-sided circuit boards 1 and 1' and the prepreg 2 that have been aligned in advance, and holes 3 are inserted into the holes 3 to hang down from the contact plate l. The provided guide pin 5 is inserted through the guide pin 5, and the guide pin 5 is further inserted into a guide hole 6 provided in the backing plate 4.

By this lamination molding, the single-sided circuit boards 1, 1' and the prepreg are integrated, forming a double-sided flat circuit board in which the circuits on both sides are immersed in the board.

However, the above conventional method has the following drawbacks.

(1) Since it is manufactured from two single-sided metal foil-clad laminates, if there is a difference in properties between the two laminates, warping is likely to occur when they are integrated.

This difference in properties cannot be avoided even if the laminates are of the same type because there are subtle variations in conditions during molding.

(2) The two single-sided metal foil-clad laminates are thin enough to have a predetermined thickness when integrated.

Therefore, warping is large, making it difficult to automate processes such as printing and etching, and even when done manually, handling is cumbersome and defects such as cracks occur frequently.

(3) When two single-sided circuit boards are laminated together with prepreg interposed, it is necessary to drill holes in the circuit board and prepreg after aligning the circuits on both sides to prevent the circuits on both sides from shifting. However, special jigs such as guide pins are required.

Further, the guide pin is easily deformed by the pressure during lamination molding, and there is a need to avoid misalignment of the circuits on both sides.

In view of the above-mentioned points, an object of the present invention is to manufacture a double-sided flat circuit board of high quality with good work efficiency and excellent mass productivity by suppressing the occurrence of defects.

The present invention will be explained according to the manufacturing process with reference to FIG.

(a) A double-sided metal foil-clad laminate 8 is produced in which a release layer 7 is interposed as an intermediate layer and only the peripheral portions are bonded together.

9 and 9' are metal foils of copper, brass, nickel, nichrome, aluminum, etc., with a suitable thickness of 18 to 70 μm.

(b) Metal foil9. The etching is subjected to normal printing and etching processing to form a predetermined circuit 10,1σ.

If necessary, the circuit 10.1σ is coated with wear-resistant metal plating, such as rhodium plating on a nickel base.

The printing and etching steps must be performed with the circuit 10 to be formed aligned 1σ.

(C) Two or three sides of the peripheral adhesive portion of the double-sided circuit board are cut and removed, and the release layer 7 is taken out.

Therefore, the double-sided circuit board is in a peeled state, leaving the adhesive portion that was not cut.

(d) Insert the prepreg 2 into the peeled part so that it has a predetermined thickness, sandwich it between metal backing plates, and heat and pressurize it.

Conditions are temperature 150-1800C1 pressure 40-150
kg/ffl and heating and pressurizing time of 30 to 60 minutes are appropriate.

Since a portion of the peripheral portion is in a bonded state, the circuits 10 and 1σ on both sides do not shift in position during this heating and pressurizing process.

(e) The circuits 10 and 10' are immersed into the substrate by the heating and pressurization, forming a double-sided planar circuit board 12.

In the heating and pressing step (d), the prepreg 2 cannot be inserted into the uncut bonded portion of the peripheral portion, and therefore, the bottom-shaped double-sided flat circuit board 12 becomes slightly thinner in that portion.

However, when using it, there will be no problem if the thin part is cut and removed.

The present invention can be applied to various conventional thermosetting resin laminates.

The present invention has the following effects.

(1) Since it is not made of two single-sided metal foil-clad laminates manufactured separately as in the past, there is no warping caused by differences in properties, and the quality is stable.

(2) Printing and etching can be done on both sides at the same time, requiring only half the process compared to conventional methods.

In addition, since printing and etching are carried out to a thickness equivalent to two conventional single-sided metal foil-clad laminates, there is less warping and ease of handling, and defects such as cracks do not occur.

(3) In the heating and pressing process for flattening the circuit, no special work or jig is required to prevent the circuits on both sides from shifting, and ordinary lamination molding can be used, which is efficient.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the molding state of a conventional double-sided flat circuit board, and FIG. 2 is a sectional view showing the manufacturing process of the present invention. 7 is a release layer, 8 is a double-sided metal foil clad laminate, 9 and 9' are metal foils, io and io' are circuits, 11 and 11' are metal backing plates, and 12 is a double-sided flat circuit board.

Claims (1)

[Claims] 1. Obtain a double-sided metal foil-clad laminate in which a release layer smaller than the prepreg is interposed in the middle of a plurality of laminated prepregs and only the peripheral portions are bonded together, and a conventional printing method is applied to both sides of the laminate.
a step of forming a predetermined circuit by etching, a step of removing the mold release layer by removing at least a portion of the integrally bonded peripheral portion of the laminate, and a predetermined number of prepreg sheets between the layers from which the mold release layer has been removed. A manufacturing method for double-sided flat circuit boards, which consists of the process of inserting the board, sandwiching it between metal plates, and heating and pressurizing it.