JPH1022609A - Drying method and process equipment of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain wet treatment without generating through hole disconnection, by dipping a printed wiring board in heating water after wet treatment, pulling up the board from the heating water, and drying the board. SOLUTION: After a printed board 5 is clipped and treated in boiling water, it is introduced in a hot-air drying machine 15 by using an introducing carriage taking-out equipment. Hot air is blown against the printed wiring board 5 from a hot-air blower 16, and vapor drying is accelerated. Thereby liquid is not left in through holes, and tent break of a dry film, through hole disconnection and surface denaturation are scarcely generated, in an outer layer pattern forming process after copper plating. Since wet treatment is possible without generating through hole disconnection, a printed wiring board of high quality can be manufactured with high yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying a multilayer printed wiring board, and a processing apparatus for a printed wiring board which can use such a drying method. TECHNICAL FIELD The present invention relates to a method for drying a multilayer printed wiring board suitable for the method and a processing apparatus for a printed wiring board that can use such a drying method.

[0002]

2. Description of the Related Art A multilayer printed wiring board (hereinafter simply referred to as a printed wiring board) is formed by laminating and bonding a plurality of inner layer cores each having a conductor pattern, then drilling through holes, copper plating in the through holes, and outer layers. It is generally manufactured through a process of forming a conductor pattern, forming a solder resist for preventing solder adhesion, and finally performing a rust-proofing process (rust-proofing process with an organic liquid) on the copper plating portion. In this manufacturing process, wet processing using various chemical solutions such as an etching solution and a copper plating solution is applied. As a final treatment in each wet treatment step, the product is dried and then sent to the next step. In particular, the wiring board after the drilling process is liable to have a treatment liquid or washing water remaining in the through-holes, and needs to be sufficiently dried after the wet processing.

[0003] Regarding this problem, FIG. 1 is a cross-sectional view of a through hole portion of a printed wiring board after an outer layer pattern forming step.
And will be described. As shown, a copper plating portion 26 is formed in the through hole 24 of the printed wiring board 21. On the surface of the printed wiring board 21, a dry film resist 22 is laminated as an etching resist. In the dry film resist 22, the entrance of the through-hole is partially dissolved by the action of the residual liquid in the through-hole 24, causing so-called tent tear. Then, in a later step, the etchant may enter the through-hole and cause the through-hole disconnection 25 to occur. Therefore, drying inside the through hole is an important problem.

Further, if an alkaline solution such as a chemical copper plating solution remains in the through-hole, tent tearing is remarkably caused. Therefore, when chemical copper plating is used in the copper plating process, cleaning and cleaning after plating are particularly required. It is necessary to dry sufficiently.

[0005] As a drying method, a conveyor-type hot air dryer is used in a horizontal transfer type wet process such as an etching or peeling process, and a slit type hot air blower or a closed type is used in a wet process using a vertical processing tank such as a copper plating process. It is common to use a hot air dryer.

[0006] As a prior art relating to this, Japanese Patent Application Laid-Open No. Hei 3-30330 is cited. In this technology, hot water is injected into a chamber containing a substrate, the substrate is immersed in the hot water, and then the pressure in the chamber is reduced to the vapor pressure of the hot water or less, and the hot water is boiled, followed by pure water in the chamber. The substrate is injected to rinse the substrate, and then the water in the chamber is drained and the inside of the chamber is evacuated.

The technique described in Japanese Patent Application Laid-Open No. Sho 62-295485 discloses a method of pre-treating plating in a through hole, in which a printed circuit board is immersed in a processing solution such as water and then the processing solution is boiled. Thereafter, the treatment liquid is cooled.

[0008]

SUMMARY OF THE INVENTION The above-mentioned JP-A-3-303
The prior art described in Japanese Patent No. 30 has a problem that since the substrate is rinsed with pure water and then evacuated and dried, the temperature of the substrate is lowered and it is difficult to sufficiently dry the substrate. In particular, a printed wiring board having a large thickness has a large heat capacity, so that short-time drying treatment results in insufficient drying, and there is a problem that the treatment liquid easily remains in the through holes.

The prior art described in Japanese Patent Application Laid-Open No. 62-295485 is for removing air in a through-hole to prevent plating defects from occurring due to the presence of air. There was a problem that was not taken into account.

[0010] A first object of the present invention is to provide a method for drying a printed wiring board capable of producing a high quality printed wiring board. A second object of the present invention is to provide a processing apparatus using such a method for drying a printed wiring board.

[0011]

In order to achieve the first object, a method for drying a printed wiring board according to the present invention comprises the steps of: wet-treating a printed wiring board; immersing the printed wiring board in heated water; And drying treatment.

The wet processing may be any of wet processing using various chemicals such as an etching solution and a copper plating solution.
It is particularly preferable to use this drying method at the time of copper plating. The heating water is preferably boiling water, but may be any heating water having a temperature of about 80 ° C. or higher.

In the drying process, if the printed wiring board is pulled up from the heated water in a state where the temperature of the entire printed wiring board is sufficiently high, the moisture can be evaporated and dried together with the steam. When using this method, the heating water is preferably boiling water. The drying treatment can be performed by drying with hot air or under reduced pressure. When drying with hot air, the temperature of the hot air is preferably equal to or higher than the boiling temperature of water.

Further, in order to achieve the second object,
The printed wiring board processing apparatus of the present invention includes a wet processing unit for wet-processing the printed wiring board, a heated water processing unit for immersing the wet-processed printed wiring board in heated water, and an immersion in the heated water. The printed wiring board is configured to include drying processing means for drying the printed wiring board, and transport means for transporting the printed wiring board to each of the above means. The wet process is, for example, a copper plating process, an etching process, or the like.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method and apparatus for drying a printed wiring board according to the present invention will be described below in detail with reference to the drawings. FIG. 2 is a perspective view of one embodiment of the processing apparatus of the present invention. Copper plating apparatus 13 which is an example of wet processing means
A drying device 12 and a loading / unloading device 2 are provided. The copper plating apparatus 13 comprises a degreasing tank, a washing tank, a soft etching tank, a washing tank, a catalyst treatment tank, a washing tank, a chemical copper plating tank, and a washing tank (only some tanks are shown in the figure). The printed wiring board is degreased with an alkaline aqueous solution containing a surfactant in the order described above by the loading / unloading device 2;
After washing with water, the surface of the copper portion is soft-etched, washed again with water, treated with a catalyst in the through hole, further washed with water, and then plated with copper. The copper-plated substrate is put into a washing tank 14 and washed, and then put into a drying device 12 and dried.

The drying device 12 will be further described. FIG. 3 is a configuration diagram of the boiling water treatment tank 1 and the loading / unloading / unloading device 2 of the drying device. Deionized water having an electric conductivity of 1 μS / cm or less is used as the water 3 for boiling, and the water 3 is boiled by the heater 4 through which superheated steam is passed. The printed wiring board 5 is set on the carrier 6 of the loading / unloading device 2, is suspended from the rail 7 and moves from the left side of the figure, and the arm 8 is moved up and down into the boiling water treatment tank 1 for a predetermined time. It is immersed. The processing time varies depending on the material, layer configuration, and thickness of the printed wiring board. For example, two layers having a thickness of about 0.5 mm have a thickness of about 5 minutes, and 50 layers have a thickness of 7 m.
For about m, it is about 10 minutes. Thereafter, the printed wiring board 5 is taken out from the boiling water treatment tank 2, and the moisture in the through hole and on the surface is evaporated and dried.

The treatment of the printed wiring board is not necessarily boiling water, but may be heating water of about 80 ° C. or higher. However, in the case of such a single treatment system using only boiling water, it is preferable to perform the treatment with boiling water. The boiling water treatment tank 1 may be provided with a supply port for adding deionized water when the service water 3 runs short. The additional deionized water may be supplied after being heated or heated in advance. Further, a drain port for overflow or a normal drain port may be provided below the boiling water treatment tank.

FIG. 4 is a block diagram of another example of the drying apparatus, which comprises a boiling water treatment tank 1 and a decompression chamber 9. As in the embodiment shown in FIG. 3, after the printed wiring board 5 is immersed in boiling water, the pressure-reducing chamber 9
And dried under reduced pressure. The decompression chamber 9 includes a flange 10 and a vacuum pump 11 for maintaining the hermetic seal.
According to this method, drying can be performed in a shorter time than in the single treatment method using only boiling water shown in FIG. In addition, it is effective to transport the printed wiring board pulled up from the boiling water into the decompression chamber in the shortest possible time to enhance the drying effect.

FIG. 5 shows a boiling water treatment tank 1, a hot air drier 15
FIG. 2 is a configuration diagram showing an embodiment of a drying device made of. As in the embodiment shown in FIG. 3 or FIG. 4, after the printed wiring board 5 is immersed in boiling water,
Into a hot-air dryer 15 and a hot-air blower 16
Thus, a hot air is blown onto the printed wiring board 5 to promote evaporation and drying. Also in this case, it is preferable that the printed wiring board pulled up from the boiling water is conveyed to the hot air dryer in as short a time as possible.

In the conventional hot-air drying method, it is difficult for hot air to enter into the small-diameter through-hole, and when the plate thickness is large, the heat capacity is large. The processing solution was liable to remain. On the other hand, in the printed wiring board dried by the method as in the present embodiment, no liquid remains in the through-hole, and the tent tear of the dry film, the breakage of the through-hole, and the surface deterioration occur in the outer layer pattern forming step after the copper plating. Was almost never.

[0021]

As described above, according to the present invention, high-quality printed wiring boards can be produced at a high yield because wet processing can be performed without causing through-hole disconnection.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a through-hole portion of a printed wiring board processed by a conventional processing method.

FIG. 2 is a perspective view of an embodiment of the processing apparatus of the present invention.

FIG. 3 is a configuration diagram of one embodiment of a drying device of the present invention.

FIG. 4 is a configuration diagram of another embodiment of the drying device of the present invention.

FIG. 5 is a configuration diagram of still another embodiment of the drying apparatus of the present invention.

[Description of Signs] 1 ... Boiling water treatment tank 2 ... Injection / conveyance removal device 3 ... Water supply 4 ... Heating heater 5 ... Printed wiring board 6 ... Carrier 7 ... Rail 8 ... Arm 9 ... Decompression chamber 10 ... Flange 11 ... Vacuum pump 12 ... Drying device 13 ... Copper plating device 14 ... Washing tank 15 ... Hot air dryer 16 ... Hot air blower 21 ... Printed wiring board 22 ... Dry film resist 24 ... Through hole 25 ... Through hole disconnection 26 ... Copper plating part

Claims (5)

[Claims] 1. A method for drying a printed wiring board, comprising the steps of wet-treating a printed wiring board, immersing the printed wiring board in heated water, pulling up the printed wiring board from the heated water, and drying the printed wiring board. 2. The method for drying a printed wiring board according to claim 1, wherein said heating water is boiling water. 3. The method for drying a printed wiring board according to claim 1, wherein the drying is performed by hot air. 4. A wet processing means for wet-processing a printed wiring board, a heated water treatment means for immersing the wet-processed printed wiring board in heated water, and a printed wiring immersed in the heated water. Drying treatment means for drying the plate,
An apparatus for processing a printed wiring board, comprising transport means for transporting the printed wiring board to each of the above means. 5. The printed wiring board processing apparatus according to claim 4, wherein said wet processing means is a copper plating processing means.