JPH11121926A - Multilayer printed wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the adhesion property with a conductor circuit and to improve reliability even when a high melt-point resin such as fluororesin is adopted for a substrate and an interlayer insulation material, by forming an alloy roughened layer on the surface of the conductor circuit. SOLUTION: A copper-clad laminate where a copper foil 2 being roughed on one surface is laminated is used for both surfaces of a substrate where fluororesin is impregnated into a glass cloth, the pattern of an etching resist 3 is formed on one surface at a side where conductor circuit is formed and is etched, and then the etching resist 3 is peeled and removed, thus forming a conductor circuit 4. Then, electroless plating is made and a roughened layer 6 of Cu-Ni-P alloy is provided on the surface of the conductor circuit 4, thus obtaining a circuit substrate. As a result, even when a high melt-point resin such as fluororesin is adopted for a substrate or an interlayer insulation material, adhesion property as the conductor circuit is secured, thus obtaining a multilayer printed wiring board with improved reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board and a method for manufacturing the same, and proposes a multilayer printed wiring board which does not peel off when heated and has excellent reliability even when a high melting point resin such as a fluororesin is used. I do.

[0002]

2. Description of the Related Art As a method of manufacturing a multilayer printed wiring board, a circuit board is conventionally formed by etching a surface copper foil of a so-called copper-clad laminate in which copper foil is stuck on both sides of a resin board. Then, after laminating the circuit boards via a film made of glass cloth and resin called a prepreg, there is a method in which the laminated board is heated and pressed to form a multilayer printed wiring board. In this method, in particular, a copper-clad laminate whose surface is roughened is used in order to improve the adhesion to the prepreg.

However, a copper-clad laminate having a roughened surface has poor followability of an etching resist, and invites an etchant to obtain a fine pattern.
Not suitable for producing fine patterns. Therefore, in order to prevent the intrusion of the etchant and form a fine pattern, a copper-clad laminate in which a copper foil whose surface is roughened only on the resin substrate side (the opposite side is a glossy surface) is adhered to the resin substrate (see FIG. 1 (a-1)), the copper-clad laminate is etched through a resist to form a conductor circuit, and the surface of the conductor circuit is treated with sodium hypochlorite, sodium hydroxide, phosphoric acid, etc. Roughening treatment (blackening treatment) with an oxidizing solution composed of sodium to form cupric oxide (roughened layer) on its surface,
By hot-pressing this through a prepreg,
Manufacture of multilayer printed wiring boards.

In recent years, a material having a low dielectric loss tangent, such as a fluororesin, has been used as a substrate for a high frequency circuit board as a substrate for a wiring board or an interlayer insulating resin. Therefore, the inventors prototyped a multilayer printed wiring board by the above-described method using a copper-clad laminate made of a fluororesin substrate and a fluororesin film as an interlayer insulating resin.

[0005]

However, in the multilayer printed wiring board manufactured by the above-described method, peeling was observed between the conductor circuit and the interlayer resin insulating layer made of the fluororesin film. Therefore, a main object of the present invention is to provide a multilayer printed wiring board that ensures high adhesion to a conductor circuit and has excellent reliability even when a high melting point resin such as a fluororesin is used for a substrate or an interlayer insulating material. It is in. Another object of the present invention is to propose a method which is advantageous for manufacturing the multilayer printed wiring board.

[0006] To achieve the above object, the inventors have made intensive studies on the cause of peeling between a conductive circuit and a fluororesin insulating layer. As a result, the cause of the delamination is that when the temperature of the laminated substrate is increased to about 350 ° C when hot-pressing the laminated substrate through a fluororesin with a high melting point, the cupric oxide (roughened layer) is altered and becomes brittle. And found the present invention.

[0007]

That is, the gist of the present invention is as follows. (1) In a multilayer printed wiring board in which a circuit board having a conductor circuit on at least one surface of a high melting point resin board is laminated via a high melting point resin insulating layer, an alloy roughened layer is formed on the surface of the conductor circuit. It is a multilayer printed wiring board characterized by being performed. The high melting point resin preferably has a melting point of 150 ° C. or higher.

(2) A conductor circuit is formed by etching at least one side of a conductor foil forming substrate having conductor foils adhered to both sides of a high melting point resin substrate to form a circuit board, and an alloy is formed on the conductor circuit surface of the circuit board. A method for manufacturing a multilayer printed wiring board, comprising: providing a roughened layer, laminating the circuit boards via a high-melting-point resin film, and heat-integrating the circuit boards. The heating press is preferably performed by heating to 150 ° C. or higher.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In a multilayer printed wiring board according to the present invention, a roughened alloy layer composed of a needle-shaped alloy layer or an uneven alloy layer is formed as a roughened layer on the surface of a conductive circuit, and the roughened alloy layer is heated. Is not deteriorated, so that peeling does not occur between the interlayer resin insulating layer and the conductor circuit. In addition, the multilayer printed wiring board of the present invention can use a copper-clad laminate to which a copper foil having only one side roughened is attached, so that a fine pattern can be formed by etching while preventing intrusion of an etching solution.

In such a multilayer printed wiring board,
The use of a roughened alloy layer such as a needle-shaped alloy layer or an uneven alloy layer as a roughened layer formed on the surface of a conductor circuit requires heating (200 ° C or higher).
This is because a strong adhesion to the resin layer can be maintained without being deteriorated by the heat treatment. In particular, this alloy roughened layer is desirably made of a copper-nickel-phosphorus alloy. This is because it can be formed by electroless plating. Generally, alloyed metals are:
Since it is harder and tougher than a single metal, it does not deform due to stress or peel off or swell due to the destruction of the roughened structure. For this electroless plating, copper sulfate 1-40g
/ L, nickel sulfate 0.1-6.0 g / l, citric acid 10-20
g / l, hypophosphite 10-100 g / l, boric acid 10-40 g
/ L, a plating aqueous solution having a liquid composition of 0.01 to 10 g / l of a surfactant is used.

[0011] The surface of the needle-shaped alloy layer is a layer of at least one metal selected from titanium, aluminum, zinc, iron, indium, thallium, cobalt, nickel, tin, lead, bismuth, or gold, A layer of a noble metal made of silver, platinum, palladium, or the like may be provided. The thickness of these metal layers is preferably 0.1 to 2 μm. Of these metals, tin is particularly advantageously used. The reason is that tin can form a thin layer by electroless displacement plating and can follow the roughened layer. In the case of tin, tin borofluoride-thiourea or tin chloride-thiourea liquid is used. In this case, a Sn layer having a thickness of about 0.1 to 2 μm is formed on the surface of the roughened layer by the substitution reaction of Cu—Sn. In the case of a noble metal, a method such as sputtering or vapor deposition can be adopted.

The high melting point resin of the present invention has a melting point of 150 ° C.
The above is desirable. This is because it is particularly effective when heating and pressing at 150 ° C. or higher. Among them, a high melting point resin having a melting point of 200 ° C. or more is optimal because it does not melt when the solder is melted. As such a resin, a so-called engineering plastic is suitable. Specifically, a fluororesin such as polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), polyphenylene ether (PPE), and polyetherimide (PEI) A thermoplastic resin such as polyphenylene sulfone (PPES) can be used. Among them, fluororesin is advantageously used because it has a small dielectric loss tangent and excellent electrical characteristics. The high melting point resin may be impregnated in a glass cloth or an aramid fiber cloth.

Hereinafter, one method of manufacturing the multilayer printed wiring board of the present invention will be described. (1) First, a conductor circuit is formed by etching at least one surface of a conductor foil forming substrate in which conductor foil is attached to both surfaces of a high melting point resin substrate via an etching resist,
A circuit board having a conductor circuit formed on the surface of a high melting point resin substrate is manufactured.

Here, it is more preferable to use a double-sided copper-clad fluororesin substrate as the conductor foil-formed substrate to which the conductor foil is attached. This substrate is obtained by thermocompression bonding a copper foil having one surface roughened to a fluororesin substrate such as polytetrafluoroethylene (PTFE). The etching resist is formed by attaching a photosensitive dry film, exposing, and developing. The conductor circuit may be either single-sided or double-sided.
As the etching solution, an aqueous solution of sulfuric acid-hydrogen peroxide, an aqueous solution of persulfate such as ammonium persulfate, sodium persulfate, or potassium persulfate, or an aqueous solution of ferric chloride or cupric chloride is preferable.

In this circuit board, a through hole may be formed in the board with a drill, and a through hole may be formed by applying electroless plating to the wall surface of the through hole and the surface of the copper foil. Copper plating is preferred as the electroless plating. In the case of a substrate having poor plating coverage, such as a fluororesin substrate, a surface treatment such as a pretreatment agent made of organometallic sodium (trade name, manufactured by Junko Co., Ltd.) or plasma treatment is performed. If necessary, a conductive paste may be filled in the through holes, and a conductive layer covering the conductive paste may be formed by electrolytic plating.

(2) The conductor circuit surface of the circuit board formed in (1) is plated with an alloy of copper-nickel-phosphorus or the like, and a roughened alloy layer such as an acicular alloy layer is formed as a roughened layer. Form. The thickness of the roughened alloy layer is preferably 1 to 10 μm.

Further, if necessary, a layer of at least one metal selected from titanium, aluminum, zinc, iron, indium, thallium, cobalt, nickel, tin, lead and bismuth is provided on the surface of the roughened layer. Or gold,
A layer of a noble metal made of silver, platinum, palladium, or the like may be provided. Of these metals, tin is particularly advantageously used. The reason is that tin can form a thin layer by electroless displacement plating and can follow the roughened layer. In the case of tin, tin borofluoride-thiourea or tin chloride-thiourea liquid is used. 0.1 ~ 2μ by Cu-Sn substitution reaction
About m m of Sn layer is formed. In this case, a Sn layer having a thickness of about 0.1 to 2 μm is formed on the surface of the roughened layer by the substitution reaction of Cu—Sn. In the case of a noble metal, a method such as sputtering or vapor deposition can be adopted.

(3) A plurality of circuit boards prepared in the above (1) and (2) are laminated via a high melting point resin film, and heated and pressed to obtain a multilayer wiring board. At this time, the outermost layer of the multilayer wiring board is a conductor foil that has not been etched. The heating temperature at this time is desirably 150 to 400 ° C.
This is because the resin is melted without being decomposed and is brought into close contact with the roughened surface of the conductor circuit. The pressing pressure is desirably 1 to 50 kg / cm ² . This is because the pressure is such that good adhesion between the circuit boards can be obtained without damaging the conductor circuit. The high melting point resin film may be not only a resin molded into a film but also a prepreg formed by impregnating glass cloth or aramid fiber cloth.

(4) The conductor foil on the outermost layer of the multilayer wiring board obtained in (3) is etched to form a conductor circuit, and thus a multilayer printed wiring board is manufactured. Hereinafter, description will be made based on embodiments.

[0020]

【Example】

(Example 1) (1) Fluorine resin impregnated in glass cloth 0.3 mm thick
18 μm thick copper foil 2 on one side of a substrate 1
Was used as a starting material (see FIG. 1 (a-1)).

A commercially available photosensitive dry film is stuck on both sides of the copper-clad laminate. A mask is first placed on one side of the conductor circuit forming side, exposed at 100 mJ / cm ² and developed with 0.8% sodium carbonate. By processing, a pattern of the etching resist 3 was formed, and the other surface was entirely exposed to obtain an etching resist 3 (see FIG. 1 (a-2)).

Next, the copper foil on the conductor circuit forming side is etched in a pattern with a mixture of sulfuric acid and hydrogen peroxide, and
The etching resist 3 was peeled off with 5% KOH to form a conductor circuit 4 (see FIG. 1 (a-3)).

(2) The substrate on which the conductor circuit 4 is formed in the above (1) is treated with a catalyst solution comprising palladium chloride and an organic acid to provide a Pd catalyst. 8 g / l, nickel sulfate 0.6 g / l, citric acid 15 g /
1, sodium hypophosphite 29 g / l, boric acid 31 g / l,
Surfactant is immersed in an aqueous electroless plating solution consisting of 0.1 g / l and pH = 9 at 70 ° C. for 15 minutes to perform electroless plating. A circuit board was obtained by providing the oxide layer 6 (see FIG. 1 (a-4)).

(3) Both sides of a 0.3 mm thick substrate 1 in which a glass cloth is impregnated with a fluororesin, a single-sided roughened thickness 18
The starting material was a copper-clad laminate (trade name: R4737, manufactured by Matsushita Electric Works) on which a μm copper foil 2 was laminated (FIG. 1 (b-
1)). Conductor circuits 4 are formed on both surfaces of the copper-clad laminate in the same manner as in (1), and a roughened layer 6 of Cu-Ni-P alloy is formed on the surface of the conductor circuits 4 in the same manner as in (2). Provided,
A circuit board was obtained (see FIGS. 1 (b-2) to (b-4)).

(4) The two circuit boards of (2) and
One circuit board of (3) was laminated via a 70 μm-thick fluororesin prepreg 7 made of glass cloth impregnated with a fluororesin (see FIG. 1 (c)).

(5) The laminated body is heated at a heating rate of 10 to 20 ° C./min, and when the temperature reaches 350 to 380 ° C., held for 50 to 60 minutes, and then pressed at a pressure of 10 kg / cm ^2. ,afterwards
The sample was cooled at a rate of 10 ° C./min (see FIG. 1 (d)).

(6) Finally, the copper foil on the outermost surface was etched according to a conventional method to form a conductor circuit 5, thereby obtaining a multilayer printed wiring board (see FIG. 1 (e)). No peeling was observed between the conductor circuit 4 and the fluororesin insulating layer 7 in the multilayer printed wiring board thus manufactured.

Comparative Example As a method for roughening the surface of a conductor circuit, sodium hypochlorite 60 g / l, sodium hydroxide
Example 1 except that the blackening treatment was performed using a treatment solution consisting of an aqueous solution of 18 g / l and sodium phosphate 5 g / l.
A multilayer printed wiring board was manufactured in the same manner as described above. In the multilayer printed wiring board thus manufactured, peeling was observed between the conductive circuit and the fluororesin insulating layer.

[0029]

As described above, in the multilayer printed wiring board of the present invention, even if a high melting point resin such as a fluororesin is used, there is no deterioration of the roughened layer on the conductor surface due to the hot press at a high temperature. No peeling is observed between the conductor circuit and the interlayer resin insulating layer. Therefore, according to the present invention, even when a high melting point resin such as a fluororesin is used for a substrate or an interlayer insulating material, it is possible to provide a multilayer printed wiring board which secures adhesion to a conductor circuit and has excellent reliability. it can. Moreover, since the multilayer printed wiring board of the present invention can use a material having a low dielectric loss tangent such as a fluororesin, propagation delay hardly occurs.

[Brief description of the drawings]

FIG. 1 is a diagram showing a process for manufacturing a multilayer printed wiring board according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 copper foil 3 etching resist 4, 5 conductive circuit 6 roughened layer 7 prepreg (interlayer resin insulating layer)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroshi Segawa 1-1 Ibiden-cho, Ibi-gun, Ibi-gun, Gifu

Claims (4)

[Claims] 1. A multilayer printed wiring board having a circuit board having a conductor circuit on at least one surface of a high melting point resin substrate with a high melting point resin insulating layer interposed therebetween, wherein a roughened alloy layer is formed on the surface of the conductor circuit. A multilayer printed wiring board characterized by being formed. 2. The multilayer printed wiring board according to claim 1, wherein the high melting point resin has a melting point of 150 ° C. or higher. 3. A conductor circuit is formed by etching at least one surface of a conductor foil forming substrate having conductor foils adhered to both surfaces of a high melting point resin substrate to form a circuit board. A method for manufacturing a multilayer printed wiring board, comprising: laminating a circuit board via a high-melting-point resin film after forming a functionalized layer; 4. The method for manufacturing a multilayer printed wiring board according to claim 3, wherein the heating press is performed by heating to 150 ° C. or higher.