JPS62214170A - Surface-treatment of inner wall of small hole - Google Patents

Abstract

PURPOSE:To coat the surface of the inner wall of each small hole pierced in a metallic plate or the like with a thin metallic film of a uniform thickness by putting a fine wire of a metallic coating material in the hole and irradiating laser light to melt and evaporate the wire. CONSTITUTION:When a metallic film is formed on the surface of the inner wall of each small hole 5 pierced in a body 6 to be treated such as a metallic plate or a printed board, a fine wire 2 of a metallic material such as copper or solder is put in the hole 5 and laser light 2' from YAG laser 1 is irradiated on the wire 2 through an optical system 3 while the wire 2 is moved. The wire 2 is melted and evaporated by the irradiation to coat the surface of the inner wall of the hole 5 with a thin copper or solder film of a uniform thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for surface treatment of inner walls of pores provided in metal plates, printed circuit boards, etc.

[Prior art and its problems]

As is well known, the inner walls of the pores are coated with various materials for the purposes of conduction, wear resistance, insulation, corrosion protection, light transmission, and the like.

Methods for applying this coating material include thermal spraying, wet plating, and CVN, but each method has many problems.

Regarding the thermal spray method, it is impossible to apply it to holes so small that a thermal spray gun cannot fit into it, and the uniformity of the film thickness is poor, on the order of several hundred microns, and reproducibility is poor.

In addition, in the wet plating method, the plating solution may attack the object, which affects the material of the object, and the film thickness tends to be thicker at the edges of the pores. There are many disadvantages such as easy to leave residue, which causes corrosion etc., and there is also a problem of pollution. Furthermore, in the OVD method, it is necessary to heat the object to be treated to a temperature of 500° C. or higher, which causes a problem in that the film thickness inside the pores becomes thinner.

[Means for solving problems]

The present invention was made to solve the above-mentioned problems, and it involves charging the coating material, for example, in the form of a thin wire, into the pores, and then irradiating the coating material with a laser to melt and evaporate it. This is a method of attaching it to the inner wall of the pore.

This surface treatment method is easy to work with and does not require heating the coating material, and the film thickness can be controlled by changing the wire diameter or the speed at which the material is moved, resulting in a uniform film over the entire pore group. Thick coating treatment is possible. Of course there is no pollution.

〔Example〕

FIG. 1 is a schematic diagram of the device used to carry out the present invention, which includes a YAG laser device 1 with maximum output ioow, an optical system 3 for guiding the laser beam 2' to the coating material 2, and a mechanism for feeding the coating material 2. The device 4 includes a device 4 (a thin wire feeding device in the embodiment), a workpiece 6 having a pore portion 5, and a guide 7 for placing the coating material 2 in the center of the pore portion 5.

As the object to be processed, for example, (printed circuit boards f: 10 with a through hole of 1.1 m in diameter are stacked, the through holes are aligned in a row, and then a fine wire drawing device 4 is used to insert a wire with a diameter of 0.01 mm into the through hole. Pay out and charge the copper wire of 1
The end of the copper wire was irradiated with a laser while moving the copper wire at a speed of w/min.

The copper melted and evaporated and adhered to the inner wall of the through hole.

In this case, the laser output is t-20W and the beam diameter is 300μ.
It was set as m.

After repeating the same operation for each through hole, next insert a 608n-Pb solder wire (φ0.511+) into this through hole, move it at a speed of 10 m/min, and irradiate the laser to solder it. was deposited on the copper.

After repeating the operations for all the through-holes, I checked the soldering performance on the automatic soldering line and found good results. Furthermore, when I examined the soldering condition using a cross-sectional microscope, I found that there were no blowholes and the film thickness was 10.0 to 1.
G, 2 ttm, the solder was uniform with a groove of 8.0 to 8.1μ. Furthermore, when a treated material and a to-be-treated material were added and films were deposited on the inner walls of the pores according to various purposes, the film thickness was measured, and it was found that the films were uniformly deposited. The adhesion conditions and results are shown in Table 1.

Table 1 Note that in this example, the material to be treated is charged inside the hole, but if the depth of the hole is shallow, it may be placed near the entrance of the hole. The laser may also be an excimer laser other than YAG or a CO2 laser.

〔Effect of the invention〕

As is clear from the examples of the present invention, if the surface treatment method of the present invention is applied to the surface treatment of the inner walls of pores, the treatment is simple and non-polluting, and can be applied to any coating material or material to be treated. Enables surface treatment with uniform film thickness.

Further, by selecting the size of the object to be treated and the feeding speed, a uniform and arbitrary film thickness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an apparatus used to implement the present invention. 1-YAG laser device 2...Coating material 3...Optical system 4...Fine line drawing device 5...Small hole 6...Workpiece 7...Guy r

Claims (3)

[Claims] (1) A pore inner wall surface treatment method characterized by placing a coating material at the entrance or inside of the pore, irradiating the coating material with a laser to melt and evaporate it, and coating the pore inner wall with the coating material. . (2) The method for treating the surface of the inner wall of a pore according to claim 1, wherein the coating material is copper. (3) The method for treating the surface of the inner wall of a pore according to claim 1, wherein the coating material is solder.