Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-06-12
2003-08-26
Vo, Peter (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S830000, C029S847000, C205S665000, C427S282000, C427S096400, C427S097100, C427S098300, C427S554000, C427S555000, C174S255000, C174S256000, C361S795000, C219S127000, C219S127000
Reexamination Certificate
active
06609297
ABSTRACT:
This application is a 371 of PCT/JP98/05398, filed Nov. 30, 1998.
1. Technical Field
The present invention relates to a process for producing a multi-layer printed wiring board, said process permitting mass production of a multi-layer printed wiring board with small-diameter via holes. Increased productivity is made possible, by driving the galvano head at a higher speed.
2. Background Art
A build-up multilayer wiring board alternately has interlayer resin insulators and conductive circuit layers, provides holes to the interlayer resin insulator layers, and then electrically connects the upper layers and lower layers by forming conductive films on the surface of the walls of these holes.
A hole (via hole) in the interlayer resin insulating layer is generally formed with the use of an exposure and developing process, which gives photosensitive property to the interlayer resin.
However, the required diameter of these via holes in a multilayer printed wiring board is almost 100 &mgr;m or less, thus it is necessary to develop technology which makes it possible to maintain this small diameter. Due to such stringent requirements, the employment of a processing method utilizing a laser beam for the boring of the holes in the build-up multilayer wiring board will now be investigated.
Technology using laser for boring is proposed, in JPA HEI 3-54884. According to this method, a light beam from a laser source is received by a processing head for deflection. Thereby, the laser beam is irradiated to a predetermined resin insulator to form a hole.
In mass production of multi-layer printed wiring boards, which have hundreds to thousands of via holes in each layer, efficient hole drilling is essential. In addition, via holes need accurate positioning for electrical connection to conductor circuits in the layers below.
Unfortunately, it has been difficult to control, with high accuracy, the position of laser irradiation for via hole drilling in mass production. This has aroused a need for a process for fabricating a multi-layer printed wiring board containing openings at accurate positions. However, the current method of manufacture can not guarantee accurate positioning of laser irradiation. Improvement in positioning accuracy is offset by a necessary decrease in head driving speed, which in turn lowers productivity.
The present invention aims to address the above-mentioned problems. It is an object of the present invention to provide a process for producing a multi-layer printed wiring board, said process permitting accurate positioning of via holes independent of the accuracy of position for laser irradiation, thereby drilling a large number of holes efficiently by laser irradiation.
It is another object of the present invention to provide a method for increasing the driving speed of the scanning head without decreasing the accuracy of positions of via holes.
DISCLOSURE OF THE INVENTION
In order to achieve the aforementioned objectives, the present invention according to claim
1
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (c).
(a) forming an interlayer insulating resin layer having a metal film, an opening formed on the metal film and a register mark on the surface thereof on a board covered with a conductor layer,
(b) removing that part of the interlayer insulating resin layer which is exposed through the opening in said metal film, by irradiation of a laser beam aimed at the opening according to data obtained by sensing the position of the register mark, thereby forming an opening through which a via hole is formed, and
(c) forming via holes and conductor circuits.
In order to achieve the invention's objectives, the present invention according to claim
2
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (c).
(a) forming an interlayer insulating resin layer on a board covered with a conductor layer,
(b) forming a metal film, an opening formed on the metal film and a register mark on the surface of said interlayer insulating resin layer, and
(c) removing that part of the interlayer insulating resin layer which is exposed through the opening in said metal film, by irradiation of a laser beam aimed at the opening according to data obtained by sensing the position of the register mark, thereby forming the opening through which a via hole is formed.
In order to achieve the invention's objectives, the present invention according to claim
3
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (d).
(a) placing a metal-clad resin film on a board covered with a conductor layer and performing hot-pressing, thereby forming an interlayer insulating resin layer having a metal film on the surface thereof,
(b) forming an opening and a register mark on said metal film,
(c) removing that part of the interlayer insulating resin layer which is exposed through the opening in said metal film, by irradiation of a laser beam aimed at the opening according to data obtained by sensing the position of the register mark, thereby forming the opening through which a via hole is formed, and
(d) forming a via hole and a conductor circuit.
In order to achieve the invention's objectives, the present invention according to claim
4
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (f).
(a) forming an interlayer insulating resin layer having a metal film, an opening formed on the metal film and a register mark on the surface thereof on a board covered with a conductor layer,
(b) removing that part of the interlayer insulating resin layer which is exposed through the opening in said metal film, by irradiation of a laser beam aimed at the opening according to data obtained by sensing the position of the register mark, thereby forming the opening through which a via hole is formed,
(c) forming a film by electroless plating on the board obtained in step (b) above,
(d) forming a plating resist on the board obtained in step (c) above,
(e) performing electrolytic plating on the part where said plating resist is not formed, and
(f) removing said plating resist and, removing by etching, the metal film and electrolessly plated film under the plating resist, thereby forming a via hole and a conductor circuit.
In order to achieve the invention's objectives, the present invention according to claim
5
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (h).
(a) forming an interlayer insulating resin layer on a board covered with a conductor layer,
(b) forming a metal film on the surface of the interlayer insulating resin layer,
(c) forming an opening and a register mark on said metal film,
(d) removing that part of the interlayer insulating resin layer which is exposed through the opening in said metal film, by irradiation of a laser beam aimed at the opening according to data obtained by sensing the position of the register mark, thereby forming the opening through which a via hole is formed,
(e) forming a film by electroless plating on the board obtained in step (d) above,
(f) forming a plating resist on the board obtained in step (e) above,
(g) performing electrolytic plating on the part where said plating resist is not formed, and
(h) removing said plating resist and, removing by etching, the metal film and electrolessly plated film under the plating resist.
In order to achieve the invention's objectives, the present invention according to claim
6
, provides a process for producing a multi-layer printed wiring board, which comprises the following steps (a) to (g).
(a) placing a metal-clad resin film on a board covered with a conductor layer and performing hot-pressing, thereby forming an interlayer insulating resin layer having a metal film on the surface thereof,
(b) forming an opening and a register mark on said metal film,
(c) removing that part of the interlayer insulating resin layer
Asai Motoo
Hiramatsu Yasuji
Hirose Naohiro
Kariya Takashi
Boswell Alan M.
Ibiden Co. Ltd.
Pillsbury & Winthrop LLP
Vo Peter
LandOfFree
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