JPS6141303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminate suitable for use as a substrate material for printed wiring boards and the like.

When a circuit pattern is formed on a substrate material of a printed wiring board having only a single type of metal layer as a conductive part by a known etching process, only a single type of metal circuit pattern, that is, a single layer circuit pattern can be formed.

The present invention provides a laminate that can simultaneously obtain two types of metal circuit patterns, a nickel circuit and a copper circuit, by only a known etching process without plating or other processes, and is less expensive than conventional methods. It is now possible to remove the film using the circuit plating method.
Since there are no problems such as surface irregularities, composition, etc. that occur after circuit formation, the performance quality is greatly improved. In addition, in nickel plating using the conventional circuit plating method, it is necessary to connect all desired circuit patterns with plating lead wires, which may be subject to restrictions in circuit design, or cutting unnecessary plating lead wires by punching or drilling after plating. However, the laminate according to the present invention does not have these disadvantages at all.

Furthermore, when a mated lead wire is placed on a metal base board, there is a possibility that burrs caused by punching may cause electrical continuity between the circuit pattern and the base metal, which could lead to a short circuit. I have no worries.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a laminate according to an embodiment of the present invention, and FIGS. 2A to 2D are diagrams for explaining the process of manufacturing a printed wiring board using this laminate.

In FIG. 1, the laminate is made of nickel layers 11, 1
3, a copper layer 12, an adhesive layer 14, and a base (substrate) 15. After a resist 16 is formed on such a laminate by a known printing method or photographic method, it is etched to obtain a desired circuit pattern (FIG. 2A). An example of a solution used in this etching process is ferric chloride, which can corrode copper and nickel.

In order to obtain a circuit pattern different from the above-mentioned circuit pattern by using a copper layer, the pre-coated resist is subjected to a film peeling process corresponding to the pattern (FIG. 2B). This processing method includes secondary exposure, secondary phenomenon, etc. in the case of a positive type photosensitive film resist.
After such film peeling, only the uppermost nickel layer 11 is etched (FIG. 3C). Methods for this etching treatment include controlling the immersion time in the ferric chloride solution mentioned above, or immersion in other solutions that can corrode nickel but not copper.

After the etching process is completed, the formed resist is peeled off to obtain a printed wiring board having the desired circuit pattern also on the copper layer (FIG. 2). That is, in this way, a wiring board is obtained in which a circuit pattern for a circuit terminal to be soldered to the copper layer and a circuit pattern for a circuit terminal to be bonded to the nickel layer are formed.

Such a three-layer metal-clad substrate is convenient for obtaining a two-stage smooth substrate as described below.

FIG. 3 is a diagram for explaining the manufacturing process of the two-stage smooth substrate.

For certain etched laminates in FIG. 2B, leaving the bottom nickel layer 13,
When the uppermost nickel layer 11 and copper layer 12 are etched, a substrate having a cross section as shown in FIG. 3A is obtained. The solution used in this etching process can etch the uppermost nickel layer 11, but
Copper layer 12 cannot be etched, or copper,
Although any of the nickel layers can be etched, it is preferable to use a material that can control the time so that at least the uppermost nickel layer is etched completely and the copper layer is etched moderately.

Further, to etch the copper layer, an alkali etchant which can corrode the copper layer but cannot corrode the nickel layer, such as ammonium persulfate, caustic potash, etc. as a main component, is used. If such an etching treatment solution is used, even if the etching treatment time is set to be somewhat longer, the thickness of the lowermost nickel layer determined in advance based on the material can be ensured.

In this respect, in the conventional half-etching process performed on a single metal layer substrate, it is not possible to easily control the etching process time as desired from the viewpoint of accurate etching depth. Next, as shown in FIG. 3B, a resist film removal process is performed. After the treatment, the insulating resin 17 is applied to the areas to be smoothed by a known method such as squeezing, printing, etc.
Embedded [Figure C], and then smoothed by polishing, etc. [Figure D]. As a result of this treatment process, the half-etching process can be easily managed, and a nickel surface can be obtained on the smooth conductor part, which has the effect of being able to be used as is as a switch contact material for slide switches, rotary switches, etc. In this case, nickel can be used as a base material for metal plating such as extremely thin gold, palladium, silver, etc. In this case, nickel can also be used as a contact material, making it possible to obtain a highly smooth surface. You can get great effects and benefits.

FIG. 4 is a diagram for explaining another use of the laminate according to the present invention.

That is, Figure A shows a wiring board for printed crossover jumper wires, and the circuit surface of this board is coated with a conductive paste 18' made of silver, copper, carbon, etc. or a mixture thereof. When forming by screen printing, it can be easily done from the above-mentioned smooth plate. This conductive paste is used as a jumper wire. Generally, in order to provide a crossover jumper wire on a board, when the jumper wire intersects with a circuit section of the board, an insulating resin layer is required at the intersection. However, the thickness of this resin layer can only be obtained with a thickness of about 8 to 15 microns by one screen printing, and as a result, the presence of pinholes and the withstand voltage due to insufficient thickness. Alternatively, there is a risk of poor insulation resistance occurring, and this risk will further increase if moisture is absorbed. Therefore, it is necessary to increase the layer thickness by repeating printing and curing of the insulating resin layer several times, and if the jumper conductor is silver-based, securing the layer thickness is especially important as a countermeasure against silver migration. Become.

The three-layer metal substrate according to the present invention is extremely useful in such cases, and by ensuring the thickness of the intermediate layer copper and the top layer nickel, the thickness of the insulating resin layer can be reduced. is also determined, so that the reliability of insulation can be sufficiently improved. Furthermore, when printing crossover jumper lines on a normal board, the additional conductor (jumper line) tends to break at a stepped portion of the board conductor. However, since there are no steps on a smooth substrate, the stability of crossover jumper line printing can be dramatically improved.

Also, as shown in Figure 4 (b), there is a jumper wire 1 inside the smooth interior.
It is also possible to set 8. According to this method, a smooth surface can be obtained and the internal circuit configuration can be made more sophisticated. Of course, the crossover jumper shown in Figure A can also be set on this smooth surface.

3C shows a board in which resin is embedded in the recessed portion, which is an etched portion, and electronic components or other components 19 are mounted within the resin.

As described above, according to the present invention, the above-mentioned objects can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a laminate according to an embodiment of the present invention, FIGS.
D is a diagram for explaining the manufacturing process of a smooth substrate using the laminate, and FIGS. 4A to 4C are diagrams for explaining the manufacturing process of a printed crossover jumper wire board using the laminate. 11, 13...Nickel layer, 12...Copper layer, 14...
Adhesive layer, 15...base.

Claims (1)

[Claims] 1. The above method is achieved by laminating a metal layer of nickel, copper, and nickel in the order of nickel, copper, and nickel on one or both sides of the substrate via an insulating adhesive layer, and etching the metal layer. A laminate board characterized by having two types of metal circuit patterns, a nickel circuit and a copper circuit, formed on a substrate.