JPH01214093A - Method of cleaning inside of hole of printed board - Google Patents

Abstract

PURPOSE:To make it possible to fully eject chips remaining inside through holes of a printed board regardless of the aspect ratio by immersing a printed board in which through holes are pierced, in a stored cleaning solution and by causing ultrasonic vibration in the solution. CONSTITUTION:Through holes 2 are pierced in a printed board 1. To clean the insides of the holes of the printed board 1, that is, to eject chips remaining inside the through holes, the printed board 1 in which said through holes 2 are pierced is immersed in a stored cleaning solution 8, and by ulrasonic- vibrating the solution 8, the chips inside the through holes 2 are ejected. For example, the printed board 1 in which the through hole 2 is pierced by, for example, drilling, is immersed in a liquid vessel 6. In that case, to make the direction of the through hole 2 vertical, the printed board 1 is preferably mounted horizontally. When an ultrasonic wave generating equipment 7 is started, water 8 is vibrated by the ultrasonic wave. The chip remaining in the through holes 2 are vibrated together with the water 8, and they are all ejected from the through hole 2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for cleaning the inside of a printed circuit board when cuttings remaining inside the through hole are removed after the through hole is drilled with a drill or the like. be.

[Conventional technology]

FIGS. 2 and 3 are a perspective view and a sectional view for explaining a conventional method for cleaning the inside of a hole in a printed circuit board. 3 is the cutting powder remaining in the through hole 2, and 4 is a high-pressure fluid ejection pipe that sprays water or abrasive fluid 5 at high pressure from a nozzle hole 4a onto the printed circuit board 1.

Next, the operation will be explained. After the through hole 2 is drilled in the printed circuit board 1 with a drill or the like, chips 3 remain inside the through hole 2, as shown in FIG. Therefore, this printed circuit board 1 is moved in the direction of the arrow in FIG. 2 by a transport device such as a roll conveyor (not shown),
The fluid 5 is ejected from the nozzle hole 4a at high pressure.

Then, the chips 3 are blown out of the through hole 3 by the fluid 5 ejected at high pressure, thereby cleaning the inside of the through hole 3.

[Problem to be solved by the invention]

The conventional method for cleaning the inside of a hole in a printed circuit board as described above has the following problems.

That is, in FIG. 3, T indicates the thickness of the printed circuit board 1, φ indicates the hole diameter of the through hole 2, and T/φ is called the aspect ratio. Experience has shown that it is difficult to sufficiently remove the chips 3 from the through hole 2. This means that in order to sufficiently remove the chips 3,
It is necessary to eject the fluid 5 almost linearly in the direction of arrow B in the figure, but if the aspect ratio is large, the plate thickness T
This is thought to be because it is practically difficult to eject the fluid 5 linearly over the entire length of the tube.

This invention was made to solve the above-mentioned problems, and regardless of the aspect ratio value, the through hole 2
It is an object of the present invention to provide a method for cleaning the inside of a hole in a printed circuit board, which can sufficiently remove chips 3 remaining inside the hole.

[Means to solve the problem]

A method for cleaning holes in a printed circuit board according to the present invention involves immersing a printed circuit board with a through hole in a stored cleaning solution, and then ultrasonically vibrating the cleaning solution to clean the cut in the through hole. It is designed to eliminate powder.

[Effect]

In this invention, the inside of the through-hole of the printed circuit board is filled with cleaning liquid over the entire area, so if this cleaning liquid is vibrated with ultrasonic waves, chips can be removed from the through-hole regardless of the aspect ratio. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 6 is a liquid tank, 7 is an ultrasonic generator disposed at the bottom of the liquid tank 6, and 8 is water as a cleaning liquid stored in the liquid tank 6.

Next, a cleaning method will be explained. First, the printed circuit board 1 in which the through holes 2 have been formed using a drill or the like is immersed in the water 8 in the liquid tank 6 . In this case, since the direction of vibration of the water 8 by the ultrasonic generator 7 is vertical, it is preferable to place the printed circuit board 1 horizontally so that the through holes 2 are oriented vertically.

When the ultrasonic generator 7 is activated, the water 8 is vibrated by the ultrasonic waves, and along with the vibration of the water 8, the chips 3 remaining in the through hole 2 are also vibrated, so that the chips 3 remaining in the through hole 2 are cleanly removed from the through hole 2. It will be removed. In other words, the water 8 serving as the cleaning liquid fills all the areas inside the through hole 2 to the end due to its properties as a fluid. Therefore, by ultrasonically vibrating the water 8, the chips 3 in the through hole 2 can be sufficiently and cleanly removed regardless of the aspect ratio value.

In addition, in the above embodiment, the case where water was used as the cleaning liquid was explained, but other solvents such as Freon may also be used.

〔Effect of the invention〕

As described above, according to the present invention, a printed circuit board in which a through hole is formed is immersed in a stored cleaning liquid, and chips in the through hole are removed by ultrasonically vibrating this cleaning liquid. This has the effect that chips remaining in the through hole can be cleanly removed regardless of the aspect ratio value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining a method for cleaning the inside of a hole in a printed circuit board according to an embodiment of the present invention, FIG. 2 is a perspective view for explaining a conventional method for cleaning the inside of a hole for a printed circuit board, and FIG. FIG. 3 is a sectional view showing the inside of the printed circuit board in FIG. 2; 1 is a printed circuit board, 2 is a through hole, 3 is a cutting powder, 6 is a liquid tank, 7 is an ultrasonic generator, and 8 is a cleaning liquid (water). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant Mitsubishi Electric Corporation

Claims (1)

[Claims] In a printed circuit board hole cleaning method in which a through hole is drilled in a printed circuit board and chips remaining inside the through hole are removed, the printed circuit board with the through hole drilled therein is immersed in a stored cleaning solution. A method for cleaning the inside of a hole in a printed circuit board, characterized in that chips in the through hole are removed by immersion in the through hole and ultrasonic vibration of the cleaning liquid.