JPS6372191A - Manufacture of circuit board - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method of manufacturing a circuit board in which a circuit is formed by transferring it.

[Background Art] ``In manufacturing circuit boards, circuits are generally formed using a subtractive method. That is, a circuit is formed by providing a metal foil on the surface of an insulating substrate using MINI, and etching the metal foil in areas other than the circuit pattern. However, this method has problems such as material loss because the metal foil is removed by etching in areas other than the circuit. In contrast to this subtractive method, there is an additive method in which a circuit is added to an insulating substrate by plating, and the present inventor proposes a method similar to the additive method in which a circuit is transferred to an insulating substrate. etc. are being considered.

That is, as shown in FIG. 3(a), the conductive carrier plate 1
A plating layer 3 is provided on the surface of the carrier plate 1 at a portion other than the circuit pattern, and then the carrier plate 1 is energized to form a circuit layer 4 on the surface of the carrier plate 1 by electroplating. The circuit layer 4 is formed in a circuit pattern on the surface of the carrier plate 1 in the portion not covered by the seven-layer nozzle 3, as shown in FIG. 3(b). Next, as shown in FIG. 3(e), the circuit layer 4 is bonded to the insulating substrate 5 while the metal resist 3 and the circuit layer 4 are held on the carrier plate 1. After bonding the circuit layer 4 to the insulating substrate 5 in this way, the circuit ff14 and the plating layer 3
By peeling the carrier plate 1 from the carrier plate 1, the circuit layer 4 is transferred from the carrier plate 1 as shown in FIG. 3(d).
is provided on the surface of the insulating substrate 5 to form the circuit board A.

In this device, since it is necessary to transfer the circuit layer 4 from the surface of the carrier board 1 to the surface of the insulating substrate 5, the adhesion of the circuit layer 4 to the carrier board 1 is reduced and the carrier board 1 is peeled off. In this case, it is necessary to prevent part of the circuit layer 4 from remaining on the carrier plate 1. However, if the adhesion of the circuit layer 4 to the carrier plate 1 is reduced, the insulating substrate 5
During the transfer process, there is a risk that the circuit layer 4 may be displaced or even cut on the surface of the carrier plate 1, making it difficult to form a circuit with high precision.

[Object of the Invention] The present invention has been made in view of the above points, and it is possible to easily transfer a circuit layer to an insulating substrate without reducing the accuracy of circuit formation, and in addition, It is an object of the present invention to provide a method for manufacturing circuit boards without the risk of layers falling off before transfer.

[Disclosure of the Invention] According to the method of manufacturing a circuit board according to the present invention, a thin metal layer 2 is formed on a conductive carrier plate 1 from the front surface to the i-edge of the back surface by plating, and this thin metal layer 1@2 A circuit layer 4 is formed with a circuit pattern on the surface of the insulating substrate 5 by plating, and then the circuit layer 4 is bonded to the insulating substrate 5 on the side opposite to the thin metal IVi2, and then the carrier plate 1 is peeled off from the thin metal layer 2. This method is characterized in that the thin metal N2 is subsequently removed to expose the circuit layer 4 on the surface of the insulating substrate 5.The present invention will be described in detail below with reference to Examples.

The carrier plate 1 is used as a transfer substrate, and is made of a metal plate having weak adhesion to a plated metal such as copper, nickel, or solder, such as a conductive metal plate such as stainless steel, titanium, or aluminum. Then, the surface of the carrier plate 1 is chemically or mechanically roughened to form a rough surface 10 as shown in FIG. , a thin metal layer 2 is formed on the rough surface 10 of the carrier plate 1 by electroplating copper, nickel, solder, etc.
) is formed by precipitation. This thin metal layer 2 only needs to be able to integrate a circuit layer 4, which will be described later, and a thickness of about 0.5 to 10 microns is sufficient. Here, the thin metal layer 2 is not only applied to the entire surface of the carrier plate 1, but also to the gA of the carrier plate 1 as shown in FIG.
The end of the thin metal N2 wraps around as an extension piece 6 from the end face to the edge of the back face. Masking 13 is applied to the back surface of the carrier plate 1 except for the edges, and electroplating is performed in this state to form the extension piece 6.
is on the back of carrier plate 1! Thin metal /! wrapped around the 1i section! 2 can be formed by plating.

After forming a thin metal layer 2 on the surface of the carrier plate 1 by electroplating as described above, a metal resist 3 is applied, exposed, and developed to form a thin metal layer 2 on the surface of the carrier plate 1, as shown in FIG. 1(e). The surface of the thin metal layer 2 is coated with a metal resist 3. Next, electroplating is performed by applying electricity to the thin metal layer 2 through the carrier plate 1, and a circuit layer is formed on the surface of the thin metal layer 2 by electroplating copper or the like. 4 is precipitated and formed. This circuit M4 is formed as a circuit pattern on the surface of the thin metal layer 2 in the exposed portion not covered by the metal resist 3. After forming the plating resist 3 and the circuit layer 4 on the carrier plate 1 in this manner, the plating resist 3 and the circuit layer 4 held by the carrier plate 1 are bonded to the insulating substrate 5. Here, when the insulating substrate 5 is formed by a laminate obtained by laminating and molding a plurality of prepregs 11 made by impregnating a base material such as paper or plastic cloth with thermosetting aflfIr such as an epoxy resin or an imide resin. Figure 1 (
As shown in e), a plurality of prepregs 11 are stacked together, and the prepreg 11 is further stacked with the circuit layer 4 and the metal resist 3 held by the carrier plate 1, and this is set between the heating plates 12 and heated and pressed. By molding
It is possible to form the insulating substrate 5 by laminating a plurality of prepregs 11 and simultaneously bond the plating layer 3 and the circuit layer 4 to the insulating substrate 5. Of course, it is also possible to apply adhesive to a pre-formed insulating substrate 5 to adhere the metal resist 3 and the circuit layer 4.

In this way, as shown in FIG. 1(f), the carrier plate 1
After the plating layer 3 and the circuit layer 4 held in place are adhered to the insulating substrate 5, the carrier plate 1 is peeled off and removed as shown in FIG. 1(g).

At this time, the thin metal layer 2 has a low adhesive strength with the carrier plate 1, and the carrier plate is easily peeled off from the thin metal layer 2. In other words, the adhesion of the metal resist 3 and the circuit layer 4 to the insulating substrate 5 is greater than that of the thin metal W to the carrier plate 1.
By forming the adhesive strength of I2 to be small, the carrier 177 plate 1 can be peeled off without fear that part of the plating layer 3 or part of the circuit layer 4 will be peeled off without remaining on the surface of the insulating substrate 5. It will end. *The carrier plate 1 and the thin metal plate 2 are designed so that the carrier plate 1 can be easily peeled off like an octopus. The vIj adhesion of the plating resist 3 to the plating resist 3 can be increased, and the position of the plating resist 3 and the circuit layer 4 can be changed to the thin metal layer 2.
The metal resist 3 and the circuit layer 4 can be transferred to the insulating substrate 5 while being held by the metal resist 3 and the circuit/l! on the insulating substrate 5. There is no risk that the circuit layer 4 will be misaligned or cut when transferring the circuit layer 4 to the insulating substrate 5 formed by the prepreg 11 at the same time as the prepreg 11 is heated and pressure molded.
In the case where the circuit layer 4 and the plating layer 3 are transferred, there is no risk that the circuit layer 4 will be misaligned or cut even if a flow of resin or the like acts on the circuit layer 4.
It is possible to form circuits with high precision. However, if the adhesion between the carrier plate 1 and the thin metal layer 2 is reduced in order to facilitate the peeling of the carrier plate 1, the results shown in FIGS.
In the process shown in Figure (e), that is, drying, developing, and curing the plated resin 3, forming the plating on the circuit M4, and adhering it to the insulating substrate 5, the thin metal layer 2 is peeled off from the carrier plate 1, and the metal layer 2 and the circuit M4 are peeled off from the carrier plate 1. There is a risk that it may fall off from the carrier plate 1. Therefore, in the present invention, as described above, when forming the thin metal layer 2 on the carrier plate 1, the extension piece 6 wraps around the edge of the back surface of the carrier plate 1. At this point, the thin metal layer 2 is attached to the carrier plate 1.
This is to prevent the thin metal layer 2 from peeling off from the carrier plate 1 and falling off during the process before the circuit layer 4 is transferred.

When the carrier plate 1 is peeled off in the process shown in FIG. 1(g), the extension piece 6 may be cut at the side edge of the carrier plate 1 to separate it from the thin metal layer 2.

After the carrier plate 1 is peeled off to expose the thin metal layer 2 as described above, the thin metal layer 2 is removed by chemical etching or mechanical grinding.
As shown in Figure (h), a circuit board A is obtained in which the plating layer 3 and the circuit/[4 are exposed on the surface of the insulating substrate 5 and the circuit layer 4 is provided on the surface of the insulating substrate 5 while being transferred from the carrier plate 1. be able to.

[Effects of the Invention] As described above, in the present invention, a thin metal layer is formed on the surface of a conductive carrier plate by plating, and a circuit layer with a circuit pattern is formed on the surface of this thin metal layer by plating. Then, after adhering the circuit layer to the insulating substrate on the side opposite to the thin metal layer, the carrier plate is peeled off from the thin metal layer, and then the thin metal layer is removed to expose the circuit layer on the surface of the insulating substrate. As a result, by forming the thin metal layer to have a small adhesion to the carrier plate, the carrier plate can be easily peeled off and the circuit layer can be easily transferred to the insulating substrate. Even if the adhesion between the carrier plate and the thin metal layer is reduced in order to make it easier to peel off the carrier plate, the adhesion of the circuit layer to the thin metal layer can be increased. It is possible to transfer a circuit layer to an insulating substrate while being held by the layer, and to form a circuit with high precision without fear of the circuit layer being misaligned or cut when transferred to the insulating substrate. Moreover, since the thin metal layer is formed on the carrier plate from the front side to the edge of the back side, the part that wraps around the edge of the back side of the carrier plate does not touch the edge of the carrier plate. If the thin gold IK layer is held on the carrier plate at this point, the thin metal layer may peel off during the process before transferring the circuit layer and the circuit layer may fall off the carrier plate. It is something that can be prevented.

[Brief explanation of the drawing]

FIGS. 1(a) to (h) are sectional views of each step in an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a part of the same, and FIGS. 3(a) to (d) are conventional It is a sectional view of each process part of an example. 1 is a carrier plate, 2 is a thin metal layer, 4 is a circuit layer, and 5 is an insulating substrate.

Claims (1)

[Claims] (1) A thin metal layer is formed on a conductive carrier plate from the front side to the edge of the back side by plating, a circuit layer with a circuit pattern is formed on the surface of this thin metal layer by plating, and then a circuit is placed on an insulating substrate. A circuit characterized in that the carrier plate is peeled off from the thin metal layer after the layers have been adhered on the side opposite the thin metal layer, and the thin metal layer is then removed to expose the circuit layer on the surface of the insulating substrate. Method of manufacturing the board.