JP2005349418A - Trepanning apparatus for printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drill a through hole by rotary locus processing only along the outer circumference of the hole and also to protect a machining lens against scattering matters in the machining. <P>SOLUTION: A trepanning apparatus for a printed circuit board drills a hole larger than a laser beam diameter by rotating a laser beam 20 along the outer circumference of the hole 16, wherein the apparatus is equipped with a housing 30 having an exhaust port 34 which is arranged, in a manner covering a machining area, between the printed circuit board 10 and the machining lens 22 for emitting a laser beam 20 to the board 10, and is also equipped with an exhaust mechanism 40 which sucks in the matters scattered in the machining and the wrecks 18 inside the hole to discharge them from the exhaust port 34 to the outside of the housing 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printed circuit board trepanning apparatus for making a hole larger than a laser beam diameter by turning a laser beam along the outer periphery of the hole. In particular, the present invention relates to a trepanning apparatus for a printed wiring board capable of forming a hole by turning trajectory processing of only the outer periphery of the through hole, which is suitable for use in forming a through hole (through hole) in a printed wiring board.

  As shown in FIG. 1, a printed wiring board (PCB) 10 having a thickness of about 0.1 to 0.4 mm and having a diameter of about 200 to 300 μm is coated on both sides of the insulating resin 12 with a copper foil 14 as a conductor. Conventionally, a mechanical construction method for controlling a mechanical drill (referred to as a mechanical drill) by numerical control is generally used when a through hole is formed. In the figure, 13 is a glass fiber in the insulating resin 12.

  On the other hand, with the recent increase in the density and miniaturization of printed wiring boards, there is an increasing demand for through holes having a small diameter of 100 μm or less. However, when such a small-diameter through hole is opened with a mechanical drill, the drill bit is broken at about 2000 holes, and there is a problem that the running cost becomes short with a short life.

  On the other hand, Patent Documents 1 and 2 describe a method of making a through hole using a laser beam. In particular, when making a hole larger than the laser beam diameter, as shown in FIG. It is described that a so-called trepanning method of turning the laser beam 20 along the outer periphery is described. In the figure, 22 is a processing lens made of, for example, an fθ lens, 24 is a processing head, and 26 is a chuck plate for fixing the PCB 10.

JP 2000-263263 A Japanese Patent Laid-Open No. 2004-87879

  However, when the laser beam 20 is swung along the outer periphery of the through hole 16, a machining residue 18 is generated at the center thereof, and therefore it is necessary to irradiate the laser beam 20 also on the center portion to fly the machining residue 18. . Further, the processed lens 22 may be damaged due to scattered objects during processing.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to enable a through hole to be opened by turning trajectory machining only on the outer periphery of the through hole.

  The present invention relates to a processing lens and a print for irradiating a printed wiring board with a laser beam in a trepanning processing apparatus for a printed wiring board that makes a hole larger than the laser beam diameter by turning the laser beam along the outer periphery of the hole. An exhaust unit disposed between the wiring boards so as to cover the processing region, and an exhaust unit that sucks out the scattered matter and the debris inside the hole from the exhaust port and exhausts the case out of the case. By solving, the above-mentioned problem is solved.

  According to the present invention, a through hole can be formed by turning trajectory machining only on the outer periphery of the through hole, and productivity is improved. Further, scattered objects during processing and debris inside the holes can be removed, and the yield of drilling the printed wiring board can be improved, and an accident that the processed lens is damaged by the scattered objects can be prevented. As a result, a small-diameter through hole can be machined at a low running cost compared to the conventional mechanical type.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In order to form the through hole, it is necessary to make a copper foil layer (conductive layer). In order to directly process the copper foil 14 with a laser beam, a harmonic solid-state laser (for example, a UV laser) having a wavelength with a high absorption rate (for example, 355 nm) is suitable. A third harmonic solid-state laser is desirable, but a fourth harmonic may be used. In order to protect the quality of the through hole, it is necessary to reduce the bulge and scattering of the surface copper foil and increase the aperture ratio. As a result of experiments, it was found that the processed surface energy density is preferably 30 J / cm ² or more. When the energy is low, the tip of the glass fiber 13 in the insulating resin 12 protrudes into the through hole 16 as illustrated in FIG.

  In order to achieve the above energy density, the spot diameter of the laser beam is reduced to a diameter of 30 μm. For example, when a through hole having an outer diameter of 100 μm is formed, trepanning is performed with a turning trajectory so that the outer periphery becomes 100 μm. In order to remove the processing residue 18 as shown in FIG. 2 that occurs at this time, in the present invention, as in the embodiment shown in FIG. 4, the housing 30 that covers the processing region is replaced with the processing lens 22 and the printed wiring board 10. Provide between.

  The casing 30 uses a material having a high transmittance (for example, an acrylic material having a transmittance of 99% in the UV region) where the laser beam 20 passes, and avoids attenuation of the laser beam 20. Further, the housing 30 is provided with an exhaust port 34 and exhausted by an exhaust mechanism 40 provided outside, so that scattered matter and processing residue 18 at the time of forming the through hole are sucked and discharged to the outside through the exhaust port 34. Let

  Here, as a laser beam having a wavelength in the ultraviolet (UV) region, the fourth or fifth harmonic of the Nd: YAG laser can be used in addition to the third harmonic of the Nd: YAG laser. A YLF laser or a YVO4 laser may be used instead of the Nd: YAG laser. Further, a fundamental wave of a KrF excimer laser or a XeCl excimer laser may be used.

  In the embodiment, the copper foil is processed. However, the processing target is not limited to this, and other metal foils such as an aluminum foil and a gold foil can be processed in the same manner.

Sectional drawing which shows the structure of the printed wiring board which is a processing object (A) Cross-sectional view around processing head and (B) Plan view of printed wiring board showing problems to be solved by the present invention Cross-sectional view of the same printed wiring board Sectional drawing which shows the structure of embodiment of this invention

Explanation of symbols

10 ... Printed wiring board (PCB)
DESCRIPTION OF SYMBOLS 12 ... Insulating resin 14 ... Copper foil 16 ... Through-hole 18 ... Processing remaining 20 ... Laser beam 22 ... Processing lens 24 ... Processing head 26 ... Chuck plate 30 ... Housing 32 ... Laser beam passage part 34 ... Exhaust port 40 ... Exhaust mechanism

Claims (1)

In the trepanning processing device for a printed wiring board that opens a hole larger than the laser beam diameter by turning the laser beam along the outer periphery of the hole,
A housing having an exhaust port disposed between the processing lens for irradiating the printed wiring board with the laser beam and the printed wiring board so as to cover the processing area;
An exhaust means for sucking out scattered matter and debris inside the hole during processing, and discharging it from the exhaust port to the outside of the housing;
A printed wiring board trepanning apparatus characterized by comprising:

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