JPH0697651A - Production of wiring board - Google Patents

Abstract

PURPOSE:To improve the formability of fine wiring and its dimensional accuracy by making a through-hole in an insulation substrate, forming resin sheets and copper foils successively on both sides thereof after the preliminary through-hole is filled with a resin, and making a through-hole of smaller diameter than that of the preliminary through-hole in the preliminary through-hole part of the copper laminated board which is formed through heating and pressing. CONSTITUTION:A preliminary through-hole 2 of 1.2mm in diameter is made in a glass fabric/epoxy resin laminated board 1 by a mechanical drill, and after the hole is filled with a hole-filling resin sheet 3, the board 1 is provided with an adhesive resin 4 and copper foil 5 on both sides thereof and they are heated/pressed to form a copper laminated board. Then, after a through-hole 6 of 1.0mm in diameter is made in the preliminary through-hole part of the copper laminated board, a plating catalyst is adhered on the surface of the copper laminated board and the inner wall of the hole 6 to form a plating copper 7. Since the part for making a through-hole is provided with no glass fabric, a through-hole having a smooth inner wall can be formed. Therefore the wiring can be easily refined because of small thickness of panel copper plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board having excellent fine wiring formability and dimensional accuracy.

[0002]

2. Description of the Related Art As surface mounting IC packages such as QFPs have a large number of terminals, a narrower pitch, and a smaller lead area,
There is a strong demand for the wiring board on which the wiring is mounted, to have finer wiring and to improve the alignment accuracy with the IC leads. A typical method for manufacturing a conventional wiring board is to provide a through hole with a mechanical drill in a copper-clad laminate made of glass cloth / epoxy resin or a copper-clad laminate made of glass nonwoven fabric / epoxy resin,
This is a method of forming an etching resist image on a portion to be a circuit after performing panel copper plating, and etching copper in an unnecessary portion. Since the etching of copper progresses not only in the thickness direction but also in the lateral direction, the thicker the copper, the easier the disconnection. Therefore, in order to miniaturize the wiring, it was necessary to reduce the thickness of the copper foil of the copper clad laminate or the panel-plated copper.

[0003]

However, the inner wall of the through-hole of the copper foil laminated plate using the glass cloth has a recess of about 50 μm in depth because the glass cloth is cut off by being excavated by a drill blade. Was there. In order to cover this concave portion with plated copper, plating with a thickness of 30 μm or more was required. Therefore, even when the thinnest 5 μm copper foil is used for the copper clad laminate, the limit of the wiring width / wiring interval that can be formed is 80/80 μm. On the other hand, since the glass non-woven fabric has shorter glass fibers than the glass non-woven fabric, it is less likely to be dug up by a drill blade, and the depth of the recess of the through hole inner wall of the copper-clad laminate made of the glass non-woven fabric is about 20 μm. Therefore, the panel plating thickness may be about 20 μm, and it is easier to miniaturize the wiring than the case where the copper clad laminate made of glass cloth described above is used. However, the glass non-woven fabric is not a continuous body, and the force for restraining the movement of the epoxy resin is smaller than that of the glass cloth. Therefore, a wiring board manufactured by using a copper clad laminate made of a glass non-woven fabric has a large dimensional change during reflow soldering when mounting an IC, which causes a problem that a pad of the wiring board and an IC lead are misaligned. there were. An object of the present invention is to manufacture a wiring board which has excellent fine wiring formability and high dimensional accuracy.

[0004]

According to the present invention, a through hole (hereinafter referred to as a preliminary through hole) is provided in an insulating substrate, the preliminary through hole is filled with a resin (hereinafter referred to as a hole filling resin), and then the insulating substrate is insulated. A resin sheet (hereinafter referred to as an adhesive resin sheet) and a copper foil are sequentially arranged on both sides of the substrate, and they are heated and pressed to pierce the preliminary through-hole portion of the copper-clad laminate with a diameter smaller than the preliminary through-hole. The present invention provides a method for manufacturing a wiring board, which is characterized by providing holes.

The insulating substrate applicable to the present invention is a glass cloth / epoxy resin laminated board, a glass cloth / polyimide resin laminated board, a glass cloth / bismaleimide triazine resin laminated board,
Examples thereof include glass cloth / fluorine resin laminated plate, glass cloth / polyethylene resin laminated plate, glass cloth / phenolic resin laminated plate, glass cloth / polyester resin laminated plate and the like. A laminated board using an aramid cloth may be used instead of the glass cloth of these laminated boards. Further, a ceramic substrate such as Al ₂ O ₃ , AlN, SiC, SiO ₂ may be used.

In the present invention, mechanical drilling, punching, laser and the like are available as a method of providing a preliminary through hole in the insulating substrate made of the above laminated body.

In the present invention, the method of forming the preliminary through holes in the insulating substrate made of ceramics includes punching, mechanical drilling, and the like on the green sheet before firing.
There is a method of firing the green sheet after forming the preliminary through holes with a laser or the like, or a method of using the laser after firing.

The hole filling resin applicable to the present invention is epoxy resin, phenol resin, polyimide resin, bismaleimide triazine resin, fluorine resin, polyethylene resin, polyester resin and the like. Further, an inorganic filler or rubber may be added to these resins. The inorganic filler includes short glass fiber, silicon oxide, zirconium oxide, zirconium silicate, alumina, mica, calcium carbonate and the like. Examples of the rubber include acrylonitrile / butadiene rubber, acrylonitrile / butadiene / styrene rubber, butadiene rubber, isoprene rubber, chloroprene rubber and polyethylene rubber.

In the present invention, the method of filling the prefilling holes with the hole filling resin includes a method of printing the flowable hole filling resin, or a flowable sheet-like hole filling resin (hereinafter referred to as hole filling resin). There is a method of filling the hole with a parallel plate press or a hot roll laminator. Examples of the adhesive resin sheet to which the present invention can be applied include an epoxy resin sheet, a polyimide resin sheet, a polyetheramide resin sheet, a polyetherimide resin sheet, an acrylic resin sheet, and an epoxy-acrylonitrile / butadiene rubber sheet.

The copper foil to which the present invention can be applied is a foil made of copper alone or a multi-layered copper foil made of copper such as aluminum, nickel, phosphorus and iron. The method for producing a copper-clad laminate according to the present invention includes arranging adhesive resin sheets on both sides of an insulating substrate filled with preliminary through holes, further disposing copper foils on both outer sides thereof, and a parallel plate press or an autoclave press or This is a method of heating and pressing the whole with a hot roll laminator or the like.

The through-hole forming method in the present invention is a method of forming a through-hole having a diameter smaller than that of the preliminary through-hole inside the preliminary through-hole of the copper clad laminate by mechanical drilling, punching, laser or the like. The diameter of the through hole is preferably 0.05 to 1.0 mm smaller than the diameter of the preliminary through hole.

In the wiring forming method of the present invention, after the through holes are formed in the copper foil laminate, panel copper plating is performed,
A method of forming an etching resist image on the part that will be the circuit and etching the copper of unnecessary parts, or plating the panel copper after forming the through holes, forming a plating resist image on the part that will not be the circuit, and patterning on the part that will be the circuit There is a method in which copper plating and pattern solder plating are performed, the plating resist is removed, and then copper in an unnecessary portion is etched. If necessary, the solder may be removed after etching unnecessary portions of copper.

[0013]

Since the copper clad laminate according to the present invention does not have a glass cloth at the planned through hole, the inner wall of the through hole is smooth even if the through hole is formed by a mechanical drill, and the panel plating thickness is thinner than that of the conventional technique. Therefore, the wiring can be made finer than in the conventional technique. In addition, since the copper clad laminate according to the present invention has a glass cloth, an aramid cloth, or a ceramics substrate with a small dimensional change, the movement of the resin in the wiring board can be restricted during the reflow soldering. Therefore, there is no displacement between the pad of the wiring board and the IC lead.

[0014]

Embodiments of the double-sided wiring board according to the present invention will be described below with reference to the drawings. First, a glass cloth with a thickness of 1.0 mm
A preliminary through hole 2 having a diameter of 1.2 mm was formed in the epoxy resin laminated plate 1 by a normal mechanical drill. Next, 50 parts by weight of a brominated epoxy resin for laminated plate, dicyandiamide 2.
5 parts by weight, AGP-01 / BZ (short glass fiber, product name manufactured by Asahi Shobel) 35 parts by weight, N-1032 (acrylonitrile / butadiene rubber, product name manufactured by Nippon Zeon Co., Ltd.)
A hole filling resin sheet 3 obtained by applying a varnish containing 8 parts by weight onto a polypropylene film and drying it was placed on one side of a glass cloth / epoxy resin laminate 1 as shown in FIG. Then, using a normal parallel plate press, a pressure of 40 kgf / cm ² ,
The hole filling resin sheet 3 was filled in the preliminary through holes 2 by heating and pressing at a temperature of 130 ° C. for 20 minutes. Then, on both sides of the glass cloth / epoxy resin laminate 1, the adhesive resin sheet 4 (AS
-210I, a polyimide adhesive sheet, a product name of Hitachi Chemical Co., Ltd.) and a copper foil 5 having a thickness of 18 μm are arranged, and heated and pressurized by a parallel plate press at a pressure of 40 kgf / cm ² and a temperature of 200 ° C. for 60 minutes. The copper clad laminate shown in was produced. After that, a through hole 6 having a diameter of 1.0 mm is formed in the preliminary through hole portion of the copper clad laminate with a normal mechanical drill, and then immersed in a treatment solution containing palladium chloride to form the surface of the copper clad laminate and the through hole 6. After attaching the plating catalyst to the inner wall of the
1 for 01 (electroless copper plating solution, trade name of Hitachi Chemical Co., Ltd.)
It was immersed for 5 minutes, and subsequently, copper pyrophosphate electroplating was performed to form plated copper 7 having a thickness of 20 μm to obtain a structure shown in FIG. After that, PHT-887AF- is formed on the surface of the plated copper 7.
50 (dry film photoresist, a product name of Hitachi Chemical Co., Ltd.) was laminated, exposed and developed to form an etching resist image on a portion to be a circuit. Then, the unnecessary portions of the copper foil 5 and the plated copper 7 were etched with a cupric chloride solution, and the etching resist image was peeled off to obtain the double-sided wiring board shown in FIG.

[0015]

According to the present invention, the following effects can be expected. (1) Since there is no glass cloth in the through hole planned portion, the through hole having a smooth inner wall can be formed. Therefore, the thickness of the panel copper plating may be thin, which facilitates miniaturization of wiring. (2) Since there is a structure that restrains the movement of the resin inside the wiring board, high dimensional accuracy can be secured.

[Brief description of drawings]

FIG. 1A is a sectional view of a glass cloth / epoxy resin laminate having pre-through holes formed therein and a hole filling resin sheet used in one embodiment of the present invention, and FIG. 1B is a process of one embodiment of the present invention. A cross section showing a step of forming a double-sided copper-clad laminate by filling the preliminary through holes of the laminate shown in (a) with a hole filling resin sheet and arranging an adhesive resin sheet or copper foil Figure, (c)
Is a cross-sectional view showing a step of forming plated copper by forming a through hole in the double-sided copper clad laminate shown in (b), which is a part of the step of one embodiment of the present invention, and (d) shows the present invention. FIG. 6 is a cross-sectional view showing a step of forming a double-sided wiring board by removing an unnecessary portion of the plated copper shown in (c), which is a part of the step of the example.

[Explanation of symbols]

1. Glass cloth / epoxy resin laminate 2. Pre-through hole 3. Hole filling resin sheet 4. Adhesive resin sheet 5. Copper foil 6. Through hole 7. Plated copper

Claims (1)

[Claims] 1. A copper clad laminate obtained by providing a through hole in an insulating substrate, filling the through hole with resin, and then sequentially arranging a resin sheet and a copper foil on both sides of the insulating substrate and heating and pressing them. A method of manufacturing a wiring board, wherein a through hole having a diameter smaller than that of the through hole is provided in the through hole portion of the board.