Electric heating – Metal heating – By arc
Reexamination Certificate
1999-12-20
2001-09-04
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
C219S121820, C219S121840
Reexamination Certificate
active
06285000
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a laser processing device and laser processing method whereby laser processing such as processing for the formation of minute holes is performed on an article to be processed which is in the form of a sheet, such as a circuit board, using a laser beam.
FIG. 1
shows the construction of a holding device for an article to be processed which is in the form of a sheet in a prior art laser processing device. This laser processing device
130
is constructed so as to perform laser processing by holding a sheet-like article
131
to be processed at a prescribed position.
In
FIG. 1
, through-holes
134
a
are provided on a suction plate
134
arranged on a holding base
133
. The sheet-like article
131
to be processed placed on suction plate
134
is held in a prescribed position by suction created by vacuum evacuation from vacuum evacuation port
135
. Processing to produce a minute hole is achieved by directing a laser beam on to article
131
held in this prescribed position.
FIG. 2
shows another known CO
2
laser processing device for processing the surface of an article in the form of a thin sheet consisting of a metal sheet or the like at high speed and high accuracy, in which the article is located in position and a laser beam is directed on to the surface of this article. In such a laser processing device, as shown in
FIG. 2
, the undersurface of article
41
to be processed is supported at a large number of locations by spikes
42
, leveling being achieved by utilizing the weight of this article
41
and processing being performed by directing a laser beam
43
on to article
41
from its upper surface.
However, in the prior art example shown in
FIG. 1
, when hole-forming processing of article
131
is performed by a laser beam, laser light passing through article
131
by means of the holes that are thus formed is reflected by suction plate
134
and this reflected light heats up and deforms article
131
to be processed. Since circuit board materials etc. are easily deformed by heat, through-holes for preventing reflection are provided, as a counter-measure, beforehand in suction plate
134
at positions corresponding to the positions in which the holes are to be formed in article
131
. However, since the position of such anti-reflection through-holes is different depending on the type of article
131
to be processed, it is difficult to make these correspond with a large number of product types. Although it is possible to cope with changes in the position in which processing is effected if the antireflection through-holes are formed large enough, if article
131
to be processed is thin, distortion is produced by the suction, lowering processing accuracy. Also, since article
131
to be processed is fixed in position by vacuum suction, the residue produced by processing is removed by this suction, but there was the problem of blockages being produced by this residue in parts of the suction flow path.
Further, the prior art example shown in
FIG. 2
which is employed for forming through-holes by laser processing for via electrodes in the thin resin sheet or metal sheet for multi-layer circuit boards was subject to the following problems. Specifically, thin sheet such as resin sheet has poor shape stability and is liable to curl so if this prior art method is applied to such thin sheet, large undulations are left in the vicinity of the center of the thin sheet. This gives rise to the problem that such changes in surface height may exceed the allowed range of working distance of the laser beam, making accurate processing impossible.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a laser processing device and laser processing method whereby the problems of the prior art experienced when forming holes in articles to be processed in the form of a sheet by laser processing and/or the problems occurring when subjecting an article to be processed which is in the form of a thin sheet to laser processing can be solved.
In order to achieve the above object, a laser processing device according to the present invention in which hole-forming processing is performed by directing a laser beam on to an article to be processed which is in the form of a sheet comprises at least a pair of clamps that respectively hold two opposite end parts of the article to be processed, and a tensioning device that applies tension to the article to be processed by applying a bias in a direction such as would mutually separate this pair of clamps.
Also, in a method of laser processing in which hole-forming processing is performed by directing a laser beam on to an article to be processed which is in the form of a sheet, according to the present invention, in order to achieve the above object, laser processing is performed whilst applying tension to the article to be processed by applying bias in a direction such as would relatively separate two opposite end parts of the article to be processed.
With the above laser processing device and laser processing method, an article to be processed which is in the form of a sheet is held at two end parts by a pair of clamps, and tension is applied between the two end parts which are thus held. The article can thus be held in a constant flat condition without holding the back face of the portion being processed of the article being processed by a suction plate and without vacuum suction. The laser-processed surface of the article to be processed can therefore be supported suspended in space, so reflection from a suction plate of laser light passing through the holes that are formed does not occur and there is no thermal deformation due to such reflected light. Also, there is no blockage of the suction flow path by the residue produced by processing, which is a problem in a holding structure using vacuum suction. Accordingly, stable processing can be continued.
Further, a laser processing device according to the present invention, in order to achieve the above object, comprises: clamps that apply tension to an article to be processed which is in the form of a thin sheet; a suction device that applies suction and holds in releasable manner side portions at at least two locations of the periphery of a demarcation portion such that it can maintain this demarcation portion of the article to be processed which is in the form of a thin sheet in a flat condition due to this tension; a laser beam emitting device that performs laser processing of the demarcation portion of the article to be processed which is in the form of a thin sheet, which is held by suction by the suction device; and a displacement device whereby the article to be processed which is in the form of a thin sheet is displaced relatively with respect to this laser beam emission device and suction device, so that each demarcation portion of the article to be processed which is in the form of a thin sheet is successively subjected to laser processing.
Also, in order to achieve the above object, in a laser processing method wherein laser processing is performed by directing a laser beam on to an article to be processed which is in the form of a thin sheet, in which, whilst applying tension to the article to be processed which is in the form of a thin sheet, side parts at at least two locations of the periphery of a demarcation portion are supported by suction so that this demarcation portion of the article to be processed which is in the form of a thin sheet is maintained in flat condition by this tension, this demarcation portion is subjected to laser processing which is repeated for successive demarcation portions.
With the laser processing device and laser processing method of the invention as above, since the clamps tension the article being processed which is in the form of a thin sheet and the suction device applies suction and support in a tensioned condition to the side parts at at least two locations of the periphery of a demarcation portion of the article being processed, surface undulations of the thin-sheet ar
Gawa Tomohiro
Kasai Kenji
Kawata Masahiro
Muneyuki Ken
Nakamura Akiko
Heinrich Samuel M.
Jordan and Hamburg LLP
Matsushita Electric - Industrial Co., Ltd.
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