JPH0538611A - Drilling of printed wiring board - Google Patents

Abstract

PURPOSE:To provide a drilling method of a printed wiring board capable of certainly preventing appearance of a crack and a chip on a bonded layer on the surface of a substrate at the time of drilling without thickening a batten. CONSTITUTION:In the case of manufacturing a printed wiring board by the additive process, after a bonded layer 2 formed on the surface of a substrate 1 is roughed, a batten 3 is attached on the surface of the bonded layer 2 with an adhesive, a specified hole is drilled with a drill 6 in that state, and thereafter, the batten 3 is removed from the bonded layer 2 and the adhesive is removed from the bonded layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for punching a printed wiring board, and more particularly to a method for punching a printed wiring board when a printed wiring board is manufactured by an additive method.

[0002]

2. Description of the Related Art In recent years, electronic devices have been reduced in size, mounted in higher density, made higher in performance, and made more multifunctional. Also in printed wiring boards used for these, high density and high reliability are achieved by fine patterns. Sex is required. And
A so-called through-hole double-sided wiring board in which conductor circuits (conductor patterns) formed on both surfaces of the printed wiring board are electrically connected to each other by through holes is often used.

Conventionally, as a method of forming a conductor circuit on a printed wiring board, a subtractive method of forming a conductor circuit by photo-etching after laminating a copper foil on an insulating substrate has been widely used. According to this method, it is possible to form a conductor circuit having excellent adhesion to the insulating substrate, but so-called undercut occurs due to etching due to the thickness of the copper foil, and it is difficult to obtain a high-precision fine pattern,
There is a problem that it is difficult to cope with high density. For this reason, as an alternative method to the subtractive method, an adhesive method is applied to an insulating substrate to form an adhesive layer, the surface of the adhesive layer is roughened, and then electroless plating is applied to form a conductive circuit. Is getting attention.

When a printed wiring board is manufactured by the additive method, through holes are often drilled after roughening the adhesive layer formed on the substrate surface. Conventionally, when making a hole in a substrate after roughening an adhesive layer, a hole such as an aluminum board or a paper phenol plate is placed on the substrate to make a hole.

[0005]

However, when the periphery of the hole is observed after drilling, as shown in FIG. 4, cracks 24 and chips 25 are generated around the hole 23 in the portion of the adhesive layer 22 on the surface of the substrate 21. In some cases, copper plating is performed in such a state to form a through hole, resulting in insufficient reliability of the through hole. Therefore, there is a need for a drilling method that does not cause cracks or chips during drilling.

[0006] As a result of examining the cause of cracking and chipping despite the use of a backing plate at the time of drilling,
As shown in FIG. 5, it was found that the backing plate 27 floats up from the surface of the adhesive layer 22 during drilling with the drill 26, and the backing plate 27 may not play its role.
That is, in order to smoothly discharge the cutting powder during drilling with the drill 26, the cylinder 28 is surrounded around the drilling position of the drill 26 and the substrate 21, and the cylinder 28 is suctioned to remove the cutting powder. However, the backing plate 27 was lifted by the suction action.

The thickness of the backing plate 27 is 0.
It is 1 to 0.2 mm, and it is as thin as 0.4 mm on a paper phenol plate, so it floats up due to suction. Although it is possible to prevent lifting by increasing the thickness of the backing plate 27, the layer of the backing plate which the drill must penetrate when drilling becomes thick and the drill has an extra burden, which shortens the life of the drill and reduces the manufacturing cost. There is a problem that leads to the rise of. There is also a problem that the number of substrates that can be drilled at one time is reduced and the drilling efficiency is deteriorated.

The present invention has been made in view of the above problems, and an object thereof is to reliably prevent cracks and chips from occurring in the adhesive layer on the surface of the substrate at the time of drilling without thickening the backing plate. (EN) Provided is a method for punching a hole in a printed wiring board.

[0009]

In order to achieve the above object, in the present invention, when a printed wiring board is manufactured by an additive method, the surface of the adhesive layer is roughened after the adhesive layer formed on the surface of the substrate is roughened. The backing plate was attached to the above with an adhesive, and a predetermined hole was opened in that state by a drill, and then the backing plate was peeled from the adhesive layer and the adhesive was removed from the adhesive layer.

[0010]

Function: A patch plate is attached to the surface of the roughened adhesive layer with an adhesive. When making holes with a drill, even if the suction action to remove the cutting powder reaches the backing plate, the backing plate does not float up from the adhesive layer, and the role of the backing plate is ensured and the surface of the adhesive layer is not cracked or chipped. Are prevented from occurring. After the completion of drilling with the drill, the caul plate is peeled off from the adhesive layer and the adhesive is removed from the adhesive layer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. Apply adhesive to the surface of substrate 1,
The adhesive layer 2 was formed by curing. As an adhesive, JP-A-6
As disclosed in JP-A 1-276875, a pre-cured heat-resistant resin fine powder that is soluble in an oxidant has a property that it becomes hardly soluble in the oxidant by a curing treatment. An adhesive that was dispersed in a heat-resistant resin liquid for curing was used. After roughening the surface of the adhesive layer 2, a polyvinyl alcohol aqueous solution as an adhesive is applied to the adhesive layer 2 on one side of the substrate 1, and a patch plate 3 made of a paper phenol plate having a thickness of 0.4 mm is laid on it. The backing plate 3 was attached to the substrate 1 by heating and drying at 60 ° C. for 15 minutes (FIG. 1).
The concentration of the polyvinyl alcohol aqueous solution is such that the thickness of the polyvinyl alcohol layer 4 after drying is the depth (approximately 10 μm) of the recess (not shown) formed on the surface of the adhesive layer 2 by roughening.
It is adjusted to a larger value of 20 to 30 μm.

Next, the substrate 1 was placed on the support plate 5 in the same manner as in the conventional case, and the drill 6 was drilled while the periphery of the drilling position of the drill 6 and the substrate 1 was surrounded by the cylinder 7. The cutting powder generated by drilling with the drill 6 is the cylinder 7
Is sucked and removed by a suction unit (not shown) connected to. Although the suction action of the suction part also acts on the backing plate 3, since the backing plate 3 is attached to the adhesive layer 2 via the polyvinyl alcohol layer 4, the backing plate 3 has the same thickness as a conventional backing plate. Even if there is, it does not rise from the surface of the adhesive layer 2. Therefore, the backing plate 3 surely plays a role of improving the finished state near the surface of the member to be processed during drilling.
It is possible to reliably prevent the occurrence of cracks or chips on the surface of the adhesive layer 2 around the.

After the boring of the substrate 1 was completed, the backing plate 3 was removed from the substrate 1 and the substrate 1 was washed with hot water. The backing plate 3 is relatively easily detached from the substrate 1, the polyvinyl alcohol layer 4 is easily dissolved in hot water, and the polyvinyl alcohol that has entered the concave portion of the surface of the roughened adhesive layer 2 is also completely removed. Therefore,
When the electroless copper plating is performed, the anchor effect is not deteriorated, and the copper plating layer surely enters the concave portion to strengthen the bond with the adhesive layer 2. Instead of removing the backing plate 3 from the substrate 1 in advance, the substrate 1 may be immersed in hot water with the backing plate 3 attached.

The present invention is not limited to the above-mentioned embodiment, but an aluminum board may be used as the backing plate 3 in place of the paper phenol plate, or polyvinyl alcohol may be used as an adhesive for attaching the backing plate 3 to the substrate 1. An adhesive other than an aqueous solution may be used, or an adhesive substance may be used to attach the backing plate 3 to the substrate 1. Since the adhesive is in a state of penetrating into the recesses on the surface of the roughened adhesive layer 2, it is necessary to dissolve and remove the adhesive penetrating into the recesses with a solvent after making holes. In order to avoid a decrease in the anchor effect due to the solvent attacking the roughened surface of the adhesive layer 2 during the removal treatment of the adhesive layer with the solvent, the adhesive may be a solvent that does not dissolve or deteriorate the material of the adhesive layer 2. Use a melted one.

[0015]

As described above in detail, according to the present invention, it is possible to surely prevent cracks or chips from being generated in the adhesive layer on the substrate surface at the time of punching without thickening the backing plate,
The reliability of the through hole is increased and the reliability of the printed wiring board is improved.

[Brief description of drawings]

FIG. 1 is a schematic side view schematically showing a state where a backing plate is attached on a substrate.

FIG. 2 is a schematic sectional view schematically showing a drilled state.

FIG. 3 is a schematic cross-sectional view schematically showing a state in which the caul plate has been removed and the polyvinyl alcohol layer has been removed after completion of drilling.

FIG. 4 is a schematic cross-sectional view of a main part schematically showing a state of a substrate punched by a conventional method.

FIG. 5 is a schematic sectional view schematically showing a drilled state by a conventional method.

[Explanation of symbols]

1 ... Substrate, 2 ... Adhesive layer, 3 ... Patch plate, 4 ... Polyvinyl alcohol layer, 6 ... Drill, 8 ... Hole.

Claims (1)

[Claims] 1. When a printed wiring board is manufactured by an additive method, after a roughening of an adhesive layer (2) formed on the surface of a substrate (1), a patch plate (3) is placed on the surface of the adhesive layer (2). Stick with adhesive and drill (6) in that state
To make a predetermined hole (8), and then to peel the backing plate (3) from the adhesive layer (2) and remove the adhesive from the adhesive layer (2). Method.