JPS6354800A - Manufacture of multilayer printed interconnection 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 [Field of Industrial Application] The present invention relates to a method for manufacturing a multilayer printed wiring board in which a plurality of circuits are laminated on one or both sides of an insulating board.

[Prior Art] A device disclosed in Japanese Utility Model Publication No. 55-42460 is known as a multilayer printed wiring board in which conductive circuits are laminated in multiple layers on one or both sides of an insulating board.

Therefore, when manufacturing such a multilayer printed wiring board, a copper-clad laminate in which copper foil is stretched over an insulating plate is used, and the first
After printing the circuit pattern of the first layer,
By chemically and electrically depositing the second layer circuit pattern on the second layer circuit pattern via the insulating layer,
Multilayer printed wiring boards are provided that have two layers of circuit patterns on one side.

FIG. 5 shows the manufacturing process of a multilayer printed wiring board with such a two-layer circuit, and FIG. 6 is a partially enlarged sectional view of the multilayer printed wiring board manufactured by the same process.

Then, as shown in FIG. 5, the material (copper clad laminate) was cut and the circuit pattern of the first layer was printed.

A first layer circuit pattern is formed in each etching process.

After that, an insulating layer is formed on the upper side of the first layer circuit pattern except for the joint part with the second layer circuit pattern by an underregistration fabric process, and then an insulating layer is formed on the upper side of this insulating layer. A plating base necessary for forming the second layer circuit pattern is formed by a binder coating process.

Furthermore, in order to improve the adhesion strength to the plating base, the surface of the plating base is roughened, and a second layer circuit pattern is printed after plating pretreatment, electroless copper nozzle, and electrolytic copper plating. .

A circuit pattern for the second layer is formed by each etching process.

Thereafter, after etching resist peeling and solder resist coating steps, mark printing, contouring and hole processing are carried out to produce a desired two-layer printed wiring board.

In the 6th rA, l is an insulating plate, 2 is a circuit pattern on the first layer, 3 is a connection part (terminal) of the same circuit pattern 2 with the circuit pattern 4 on the second layer, and 5 is a connection part between the first layer and the circuit pattern 4 on the second layer. an insulating layer interposed between the second layer circuit patterns 2.4;
7 each indicate a solder resist.

[Problems to be Solved by the Invention] Now, when manufacturing a multilayer printed wiring board by the manufacturing process shown in FIG. The circuit pattern 4 of the second layer is formed by forming a plating base on the insulating layer 6, and then applying electroless copper plating necessary for the subsequent electrolytic copper plating. However, in order to improve the adhesion of this electroless copper plating, the surface of the plating base is usually subjected to surface roughening treatment.

However, the surface roughening treatment of the plating base is usually
The treatment is carried out using a mixed acid of chromium and sulfuric acid, but at this time, the joint portion 3 of the first layer circuit pattern 2 with the second layer circuit pattern 4 is exposed, so this is not covered by the plating. Because it is used to roughen the surface of the substrate, it is corroded by a mixed acid such as chromium and sulfuric acid, and when this corrosion is severe, electrical continuity between the circuit pattern 2 of the first layer and the circuit pattern 4 of the second layer is lost. This has disadvantages such as damage to the circuit and disconnection of the circuit.

Therefore, the present invention was developed in view of the drawbacks of the conventional method for manufacturing multilayer printed wiring boards, and it is possible to roughen the plating base during the manufacturing process of multilayer printed wiring boards, thereby creating an electrical pattern in the circuit pattern. Another object of the present invention is to provide a method for manufacturing a multilayer printed wiring board that can be manufactured without causing deterioration of physical characteristics.

[Means for Solving the Problems] The method for manufacturing a multilayer printed wiring board of the present invention is a method for manufacturing a multilayer printed wiring board in which a plurality of circuits are provided on one or both sides of an insulating board with an insulating layer interposed therebetween. , Prior to the surface roughening treatment of the underlayer when applying a circuit on the upper side of the insulating layer, a protective film is formed to protect the exposed portion of the circuit not covered by the insulating layer, and then the underlayer is coated with the underlayer. It is characterized by subjecting it to surface roughening treatment.

[Function] The method for manufacturing a multilayer printed wiring board of the present invention includes forming a protective film on the joints or other exposed parts of the circuit pattern prior to the surface roughening process of the plating base, Such a protective film prevents deterioration of the electrical and physical characteristics of joints or other exposed parts in the circuit pattern due to the surface roughening process of the plating base.

[Example] Hereinafter, an example of the method for manufacturing a printed wiring board of the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1 and 2 are enlarged cross-sectional views of essential parts showing a first embodiment of the method for manufacturing a multilayer printed wiring board of the present invention.

FIG. 4 is an IJJ diagram of the same process.

In the case of this embodiment, "first layer and second layer circuit patterns 11 and 11' are formed on both sides of the insulating plate IO.

An example of forming a double-sided two-layer printed wiring board 20 provided with 14 and 14' is shown.

Now, in FIG. 1, 11.11' is the first layer circuit pattern formed on both sides of the insulating plate 10, and the connection is made through the through hole 15 that conducts this circuit pattern 11.11'. B(land)lla.

11a'.

Furthermore, in forming the circuit patterns 11 and 11', as shown in FIG.
A pattern corresponding to the circuit pattern 11.11' of the first layer is printed by silk printing, and then etched to form the circuit pattern 11.11'.

In this way, the first layer circuit patterns 11.11' can be formed on both sides of the insulating plate 10. After the first layer circuit patterns 11.11' are formed, the first layer circuit patterns 11.11' are
The junction 11a of the layer circuit pattern 11.11' (7).

Insulating layers 12 and 12' are formed and covered on the portions other than 11a' by the under resist coating process shown in FIG. 4.

Furthermore, after that, a plating base 13.13' is formed on the upper side of the insulating layer 12.12' except for the joint parts 11a and lla' by a binder coating process shown in FIG. 4.

After forming the plating base 13.13', and prior to the normal surface roughening process of the plating base 13.13', bonding of the first layer circuit patterns 11.11' is performed. The portions 11a, 11a' are exposed, and a protective film 16, 16' is formed on the surface of each joint portion 11a, lla' as the exposed portion to cover this.

Therefore, in the process of forming the protective film 16, 16', alkiimidazole, which easily reacts with the copper foil forming the joint portions 11a and lla' of the first layer circuit pattern 11°11', is used. An example in which a protective film 16°16' of a complex is formed by reacting the following will be described below.

In addition, as the alkiimidazole used in the following examples, a case will be described in which Glyhol R liquid (manufactured by Shikoku Kasei Kogyo Co., Ltd.) containing this as the main component is used.

Joint part 11a of first layer circuit pattern 11.11',
The surface of the copper foil is degreased with a surfactant or the like, and the oxide film coated on the surface of the copper foil is removed with a 20% aqueous ammonium persulfate solution.

In addition, after removing the oxidized film and cleaning it, it was immersed for 3 minutes in an alkiimidazole bathing solution (using Grihol R solution manufactured by Shikoku Kasei Kogyo Co., Ltd.) controlled at 50°C. The alkiimidazole selectively reacts with the copper foil of the bonding portions 11a and lla', and a protective film 16, 16' of the flukiimidazole film is formed on the surfaces of the bonding portions 11a and lla'.

Furthermore, after removing the alkyimidazole solution attached to the surfaces other than the joint parts 11a and lla' by washing with water,
By performing heat treatment at .degree. C. for 15 minutes, the chemical and physical strength of the protective coating 18, 16' can be improved.

Therefore, a protective film 16.16 is applied to the joint portions 11a and 11a'.
After forming the plating base 13 and 13' shown in FIG. 2, the surface roughening process shown in FIG.
3. After completion of the surface roughening step of 13', the joint portion 11a
, lla' are removed with a 15% aqueous hydrochloric acid solution kept at 50°C.

Further, although not specifically shown in FIG. 2, after the above-mentioned treatment process, the required double-sided two-layer printed wiring board 20 is formed through each process including the plating pretreatment process shown in FIG. 4. It is something.

(Second Embodiment) FIG. 3 is an enlarged cross-sectional view of essential parts showing a second embodiment of the method for manufacturing a printed wiring board of the present invention.

In the case of such an embodiment, in place of the alkyimidazole protective film 16.16' of the first embodiment, the bonding portion 11a of the first layer circuit pattern 11.11',
Electroless solder plating is applied to lla' to form joints 11a and 11a.
A protective film 17, 17' is formed on the la' surface and covered with this.

An example of the electroless plating is electroless solder plating using -8P-28EL manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.

Therefore, when performing the surface roughening process of the plating base 13, 13' shown in FIG. It can be processed while being protected by a protective film 17°17'.

Further, after completing the surface roughening treatment of the two plating substrates 13, 13' using the mixed acid solution of chromium and sulfuric acid, the protective coatings 17° and 17' were peeled off using a nitric acid-based solder stripping agent. Although the first embodiment is not specifically shown in FIG. 3, the required double-sided, two-layer printed wiring board 20 is formed through the steps shown in FIG. 4.

In addition, 1st. In the second embodiment, the plating base 13.
Protective coatings 16.16' and 17.17 suitable for surface roughening treatment of 13' with a mixed acid solution of chromium and sulfur.
', that is, an example in which a film is formed by alkyimidazole and electroless solder plating is described, but the present invention is not limited to each example, and the plating base 1
3. For the surface roughening treatment method of 13′, the joint portion 11a
, lla' can be selected and formed while carrying out the process.

Furthermore, although the embodiment has been given for a double-sided two-layer printed wiring board, it can also be implemented with the same effect for other multilayer printed wiring boards such as a single-sided two-layer printed wiring board.

[Effects of the Invention] As is clear from the above description, according to the present invention, exposed circuits such as joints are removed when a circuit pattern is formed using a plating base in a circuit pattern forming process on a multilayer printed wiring board. It is possible to prevent damage to patterns, significantly improve the conduction reliability of this type of multilayer printed wiring board, improve the stability of physical strength, and provide a multilayer printed wiring board with excellent quality and precision. can.

[Brief explanation of drawings]

1 and 2 are enlarged cross-sectional views of essential parts showing the first embodiment of the multilayer printed wiring board of the present invention, FIG. 3 is an enlarged cross-sectional view of essential parts showing the second embodiment of the same, and FIG. FIG. 5 is an explanatory diagram showing the manufacturing process of the inventive multilayer printed wiring board, FIG. 5 is an explanatory diagram showing the manufacturing process of the conventional multilayer printed wiring board, and FIG. 6 is a partially enlarged view of the conventional multilayer printed wiring board. 10... Insulating plate 11. 11'... First layer circuit pattern 11 a
, 11a'...Joint portion 12.12'...Insulating layer 13.13'...Plating base -14,14'...Second layer circuit pattern 15...
Through holes 16.16', 17.17'...protective film 20...
Multilayer printed wiring board Figure 1 2n Decoy, Multilayer printed wiring board Figure 2 Masashiko Figure 5 Takumi ♂ko

Claims (3)

[Claims] (1) In a method for manufacturing a multilayer printed wiring board in which a plurality of circuits are provided on one or both sides of an insulating board with an insulating layer interposed therebetween, surface roughening of the underlying layer when a circuit is attached to the upper side of the insulating layer is performed. A method for producing a multilayer printed wiring board, which comprises, prior to the treatment, forming a protective film that protects exposed portions of the circuit that are not covered by the insulating plate, and then subjecting the base layer to surface roughening treatment. (2) The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the protective film is formed of alkiimidazole. (3) The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the protective film is formed by solder plating.