JPH0783169B2 - Printed circuit board manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] A method for manufacturing a printed circuit board, wherein a circuit is formed on a copper clad laminate for a printed circuit board by a pattern plating method, wherein the copper clad laminate is mixed in a pattern after forming a resist pattern. For the purpose of providing a method for manufacturing a printed circuit board for removing dust and improving the water wettability of a pattern, when forming a circuit on a copper clad laminate for a printed circuit board on which a resist pattern is formed by a pattern plating method. , A hydrochloric acid treatment step for removing the copper oxide film, a high-pressure water washing treatment step, and a vacuum defoaming treatment step are performed in sequence, followed by a pretreatment step including treatment with a sulfuric acid chemical, and then copper plating using a copper sulfate bath. To configure.

[Industrial application field]

The present invention relates to a method of manufacturing a printed circuit board in which a circuit is formed on a copper clad laminate for printed circuit board by a pattern plating method.

With the demand for higher packaging density in recent printed circuit boards,
There is a strong demand for miniaturization of circuit patterns, and in the case of circuit pattern width, pattern formation of 100 μm or less is required.

[Prior Art] FIG. 2 shows a pattern forming process diagram of a conventional etching method. Since the conventional pattern width is as wide as 100 to 200 μm, an etching method has been used as a method of forming a circuit pattern. What is the etching method? In Fig. 2, a copper clad laminate is prepared in which copper foils B are attached to both sides of a plate-shaped resin A in the step, resist patterns C are formed on both sides in the step, and etching is performed in the step. A pattern is formed by leaving the copper foil D in the portion covered by C and removing the copper foil in the other portions by erosion, and peeling the resist C in the process. However, the circuit pattern width is 100 μm
If an etching method is used to form the following fine patterns, the difference between the upper width and the lower width of the pattern becomes large as shown in the process, and the electrical characteristic value (conductor resistance value) of the circuit cannot be satisfied. Specifically, a pattern plating method in which the difference between the upper width and the lower width of the pattern is small is used.

FIG. 3 shows a circuit formation process diagram by a conventional pattern plating method. What is the pattern plating method is to prepare a copper clad laminate in which the copper foil B, which is thinner than the copper foil shown in FIG. 2, is attached in the step shown in FIG. 3, and the opposite of the resist pattern shown in the step shown in FIG. The resist pattern C is formed thicker than the resist shown in FIG. 2, the pattern plating of two layers of the copper plating E and the solder plating F is performed in the process, the resist pattern C is peeled in the process, and the resist pattern C is peeled in the process. The exposed portion of the copper foil is eroded and removed by etching, and the solder plating F is eroded and removed by etching using a special chemical that does not act on the copper in the process to complete the circuit formation.

FIG. 4 shows a pretreatment process diagram of a conventional pattern plating method. In the figure, reference numeral 1 is a copper clad laminate after a resist pattern has been formed by development, and will be abbreviated as substrate 1 hereinafter. 2 is a suspension machine, 3 is a plurality of processing tanks arranged in a series of plating lines. The base material 1 is suspended and held by a suspending tool of a suspension device 2, vertically moved, and sequentially dipped in the treatment liquid filled in each treatment tank 3. First, the surface is degreased and cleaned with sulfuric acid + a degreasing agent and the copper oxide film is removed, and then washed with water → washed with pure water → ammonium persulfate treatment (copper oxide film removed with an alkaline chemical solution) → washed with water → sulfuric acid treatment (next To increase the affinity for the copper sulfate bath) → Washing → Washing with pure water After passing through a pretreatment step including treatment with each sulfuric acid chemical, copper plating is performed with the copper sulfate bath.

[Problems to be Solved by the Invention]

FIG. 5 is a perspective view showing an abnormal shape formed in a fine pattern. FIG. 5 (a) is a concave shape view of a circuit pattern generated by the influence of dust, and FIG. 5 (b) is water wettability. 6A and 6B respectively show a dent shape diagram of a circuit pattern that is generated due to a bad condition.

The resist pattern of the base material 1 is formed by the development process, but if the residue of the insoluble resist after development and indoor dust and the like are mixed into the fine pattern with a pattern width of 100 μm or less, the fine pattern can be obtained by normal washing or chemical treatment. There is a problem that a foreign substance cannot be removed from the inside and a defective circuit is formed which hinders the deposition of plating and significantly reduces the cross-sectional area of the circuit as shown in FIG. Further, since the resist for pattern formation is an organic substance and is hydrophobic, bubbles are left in the pattern when the substrate 1 is immersed in the treatment tank, and the chemical treatment for the portion where the bubbles are present is incomplete, so Is abnormally deposited and a defective circuit as shown in FIG. 5B is formed.

The present invention has been made in view of the above conventional problems, and provides a method for manufacturing a printed circuit board for removing dust mixed in a pattern after forming a resist pattern on a substrate and improving wettability of the pattern. With the goal.

[Means for Solving the Problems]

FIG. 1 is a schematic process drawing for explaining an embodiment of the present invention. A hydrochloric acid treatment step (a) for removing a copper oxide film, a high-pressure water washing treatment step (c), and a vacuum defoaming treatment when a circuit is formed on a substrate 1 for a printed circuit board on which a resist pattern is formed by a pattern plating method. The step (f) is sequentially performed, followed by a pretreatment step including treatment with a sulfuric acid-based chemical, and then copper plating using a copper sulfate bath.

[Work]

After forming a resist pattern on the base material 1, a hydrochloric acid cleaning process for removing various copper oxide coatings is performed, and then a high pressure water cleaning process is performed to forcibly remove foreign substances mixed in the pattern due to the pressure of water pressure. By expanding the bubbles in the pattern by the vacuum defoaming process and separating and removing the bubbles by increasing the buoyancy, the subsequent pretreatment process including the treatment with the sulfuric acid-based chemical can be performed sufficiently effectively.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. In addition, in order to make the description of the configuration and the operation easy to understand, the same reference numerals are given to the same portions throughout the drawings, and the duplicated description thereof will be omitted.

FIG. 1 shows a schematic process diagram for explaining an embodiment of the present invention. In the figure, reference numeral 4 is a belt conveyor device that passes through a series of shower chambers, and the processing liquid is sprayed from above and below onto the substrate 1 after development, which is horizontally placed on the belt conveyor, in each shower chamber. Equipped with shower device. The symbols (a) to (f) of each shower room indicate different steps. The conveyor speed is set to 0.8 m / min, and the base material 1 will be described by way of example with a thickness of 0.1 mm and a circuit pattern width of 70 μm.

In step (a), a hydrochloric acid solution prepared by diluting 35% by weight of hydrochloric acid in a ratio of 100 cc to a total amount of 1 as a treating solution is jet-cleaned on the substrate 1 to remove the copper oxide film. In the step (b), shower water washing is performed to remove the hydrochloric acid solution in the previous step by washing. In step (c), high pressure shower water washing with a water pressure of 10 kg / cm ² is performed. This water pressure is set corresponding to the thickness of the base material 1, and in the case of this example, a water pressure higher than this may damage the base material 1. In addition, the dust removal capacity sharply decreases when the water pressure is 5 kg / cm ² or less. In the step (d), the dust and the like forcedly washed out by the water pressure in the above step are completely separated from the base material 1 by a normal shower water washing, and then dried in the step (e) to complete the conveyor treatment step. .

This drying step (e) can be omitted if it can be directly connected to a plating line using a series of suspension machines 2 including the following vacuum degassing step from the conveyor processing step. Normally, patch processing is performed without direct connection, so drying is performed in order to avoid adhesion due to flying dust. The dried substrate 1 is suspended in the suspension tool of the suspension machine 2 before being transferred to the plating line.

Reference numeral 5 denotes a vacuum defoaming device, which is filled with pure water in a container having an upper lid 6 which can be opened and closed in an up and down manner, receives the base material 1 suspended by a suspension machine 2 with the upper lid 6 open, and After submerging it so that it is completely submerged, the suspension is released, the suspension is retracted upwards, the upper lid 6 is closed, and the air in the container above the water surface meets the exhaust pipe 7 by an exhaust device (not shown). By evacuating, the external pressure of the bubbles contained in the substrate 1 is reduced and expanded, and the bubbles are separated from the substrate 1 by the increased buoyancy in water. The internal pressure of the container of the vacuum degassing device 5 is adjusted to about 40 to 60 mmHg by the exhaust device.

As a result, pattern defects due to dust are
1/5, and non-precipitation of plating due to deterioration of water wettability could be reduced to 1/10.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, the removal of dust mixed in the pattern and the wettability of the base material are significantly improved, and there is an effect of greatly contributing to the improvement of the reliability of the fine pattern.

[Brief description of drawings]

1 is a schematic process drawing for explaining an embodiment of the present invention, FIG. 2 is a pattern forming process drawing of a conventional etching method, FIG. 3 is a circuit forming process drawing by a conventional pattern plating method, and FIG. Is a pretreatment process diagram of a conventional pattern plating method, and FIG. 5 is a perspective view of an abnormal shape formed in a fine pattern. In FIG. 1, 1 is a copper clad laminate (base material), (a) is a hydrochloric acid treatment step, (c) is a high pressure water washing treatment step, and (f) is a vacuum degassing step.

Claims (1)

[Claims] 1. A hydrochloric acid treatment step of removing a copper oxide film, a high-pressure water washing treatment step, and a vacuum when a circuit is formed on a copper clad laminate (1) for a printed board on which a resist pattern is formed by a pattern plating method. A method for producing a printed circuit board, which comprises sequentially performing a defoaming treatment step, then performing a pretreatment step including treatment with a sulfuric acid chemical, and then performing copper plating using a copper sulfate bath.