JP2002190658A - Circuit forming method on printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively forming a circuit on a printed- wiring board by reducing defect in a circuit pattern due to dirt, and by shortening processes in circuit formation and exposure time. SOLUTION: A resin layer 13A is provided on the copper surface of a copper- clad, a portion other than the circuit pattern of the resin layer is eliminated with a laser beam 14, copper at the portion other than the circuit pattern is exposed, a circuit pattern 13A' of the resin layer is formed, the circuit pattern of the resin layer is used as a etching resist, the copper at the portion other than the exposed circuit pattern is dissolved and removed by etching, and the circuit pattern on the resin layer is eliminated, thus forming the circuit on the copper-clad.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a circuit on a printed wiring board, and more particularly, to a method for forming a circuit on a printed wiring board with reduced defects in a circuit pattern, reduced steps, and improved production efficiency. About.

[0002]

2. Description of the Related Art Conventionally, a photo-etching method has been often used in forming a circuit on a printed wiring board.
In the photo etching method, a photosensitive resin with excellent etching resistance is provided on a copper surface to be a circuit, a resist pattern is formed by exposing and developing a circuit pattern on the photosensitive resin, and this resist pattern is exposed as an etching resist. This is a method of removing the copper in the exposed portion by etching, stripping the resist pattern, and forming a circuit using copper.

In this case, a method of exposing a circuit pattern to the photosensitive resin includes a transfer method of exposing the photosensitive resin to ultraviolet rays through a photomask, and a method of exposing the photosensitive resin using a laser beam without using a photomask. A direct drawing method for drawing a circuit pattern thereon may be used. The transfer method using a photomask has a short exposure time and is said to be suitable for mass production.However, dust from the working environment during exposure, dust from the substrate, people, equipment, etc. causes defects in the circuit pattern. Easy,
Further, the line width of the circuit pattern tends to fluctuate due to fog due to exposure.

Further, the direct writing method using a laser beam is said to be suitable for small lot production and short delivery time because it does not use a photomask, so that the type switching time is short. The same is true in that the dust easily causes defects in the circuit pattern.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in consideration of the above problems, and has been made to reduce the defects of circuit patterns due to dust generated during exposure in forming a circuit on a printed wiring board. It is an object of the present invention to provide a method for forming a circuit of a printed wiring board which can eliminate the fluctuation of the line width of the circuit, further shorten the circuit forming process, shorten the exposure time, and form the circuit at low cost. .

[0006]

According to the present invention, there is provided a circuit for forming a printed wiring board, comprising: 1) providing a resin layer on a copper surface of a copper-clad laminate; and 2) applying a laser to a portion other than the circuit pattern of the resin layer. By removing using light, the copper in the portion other than the circuit pattern is exposed to form a circuit pattern of the resin layer. 3) The circuit pattern of the resin layer is used as an etching resist for the portion other than the exposed circuit pattern. 4) A circuit forming method for a printed wiring board, comprising: dissolving and removing copper by etching; and 4) removing a circuit pattern of the resin layer to form a circuit on the copper-clad laminate.

Further, the present invention provides a method for forming a circuit of a printed wiring board, comprising: 1) providing a through hole for a through hole in a double-sided copper-clad laminate;
A first copper layer is formed on both sides and through holes of the double-sided copper-clad laminate by electroless plating and electrolytic plating. 2) A resin layer is formed on both sides and the through-holes of the double-sided copper-clad laminate on which the first copper layer is formed. Providing, removing the circuit pattern portion and the through-hole portion of the resin layer by using a laser beam, exposing the first copper layer of the circuit pattern portion and the through-hole portion; 3) the exposed circuit pattern portion of the first copper layer And forming a second copper layer on the through-hole portion by electrolytic plating; 4) forming a metal layer resistant to an etchant on the second copper layer by electrolytic plating; and 5) removing the resin layer to form a second copper layer. 6) dissolving and removing the exposed first copper layer and copper of the double-sided copper-clad laminate by etching using the metal layer as an etching resist; and 7) removing the metal layer. Forming circuits with through holes in double-sided copper-clad laminates A method for forming a circuit of a printed wiring board.

The present invention also provides a method for forming a circuit on a printed wiring board according to the present invention, wherein the laser beam is
A circuit forming method for a printed wiring board, wherein a plurality of laser beams having a beam diameter of 20 μm to 100 μm are selectively used.

The present invention also provides a method for forming a circuit on a printed wiring board according to the present invention, wherein the laser light is
A circuit forming method for a printed wiring board, wherein laser light having a wavelength of 1321 nm to 193 nm is used.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments. 1A to 1F are partial cross-sectional views showing one embodiment of a method for forming a circuit on a printed wiring board according to the present invention. As shown in FIG. 1A, as a base material, for example, a copper foil (1
2A) and (12B) are bonded to each other using a double-sided copper-clad glass epoxy board (10). The copper foils (12A) and (12B) on the front and back sides of the double-sided copper-clad glass epoxy board (10) are shown in FIG. As shown in the figure, the resin layers (13A), (13
B) is provided.

The formation of the resin layers (13A) and (13B)
A method of applying and forming a liquid resin, or a method of attaching a sheet-like resin is applied. As a material of the resin layer, an epoxy resin, an acrylic resin, a polyvinyl alcohol resin, or the like is used. In addition, the resin layer (13A),
Before forming (13B), in order to improve the adhesion of the resin, pretreatment such as mechanical polishing for giving a proper roughness to the copper foil surface and chemical cleaning with a chemical solution may be performed.

Next, a circuit pattern of the resin layer is formed using laser light without using a photomask. As shown in FIG. 1C, a portion other than the circuit pattern of the resin layer (13A) on the surface of the double-sided copper-clad glass epoxy substrate (10) is removed by drawing using a laser beam (14), and the resin is removed. A layer circuit pattern (13A ') is formed. At this time, the copper foil (12A) other than the circuit pattern is exposed.

In the present invention, as described above, the portion other than the circuit pattern of the resin layer (13A) is irradiated with the laser beam (1A).
Since dust is removed by drawing using the method 4), dust from the working environment during exposure, substrates, people, devices, etc., and at least dust of organic substances, as in the conventional method, is removed by laser light (14) during drawing. , And defects caused in the circuit pattern are reduced.

As the laser, YAG, YLF, UV,
Excimer or the like is used. The wavelength of the laser light is 132
The wavelength is preferably 1 nm to 193 nm, and the present invention is characterized in that laser light having a wavelength of 1321 nm to 193 nm is used. 1321 nm wavelength
Is the wavelength in the YLF laser, and the wavelength is 1321 nm
When the resin layer is removed by using the above laser light, for example, a CO2 laser, the appearance of a thermal processing is exhibited, and a resin residue may remain on the lower copper foil, which is not preferable.

When a portion other than the circuit pattern of the resin layer (13A) is removed by drawing using a laser beam (14), the copper foil (12A) of the portion other than the circuit pattern is exposed, and It is preferable to irradiate the laser light to such an extent that the surface portion of the copper foil (12A) is removed.

Further, in the present invention, when removing a portion other than the circuit pattern of the resin layer, a laser beam is used.
A plurality of laser beams having a beam diameter of 0 μm to 100 μm are selectively used. In the case where a portion other than the circuit pattern of the resin layer (13A) is removed by drawing using the laser beam (14), the drawing removal of the peripheral portion of the circuit pattern in the portion other than the circuit pattern is performed by, for example, about 20 μm. Using laser light with a beam diameter to reduce jaggedness generated at the periphery of the circuit pattern, make the periphery smoother, and for drawing and removing portions other than the circuit pattern periphery, other than the circuit pattern. Is performed by using, for example, a laser beam having a beam diameter of about 100 μm and improving the efficiency of drawing and removing the portion. The beam diameters of the plurality of laser beams are appropriately set according to the type of resin used, the thickness of the resin layer, the shape of the circuit pattern, and the like, and are switched by selecting an aperture.

In the present invention, as described above,
Since a portion other than the circuit pattern is drawn and removed by using a laser beam to form a circuit pattern of the resin layer, the material of the resin layer does not need to be a photosensitive resin. A photosensitive resin may be used, but a non-photosensitive resin is preferable in terms of cost.
Before forming the circuit pattern of the resin layer using laser light, a hardening treatment such as heating and exposure may be performed to further cure the resin layer.

FIG. 1D is similar to the formation of the circuit pattern (13A ') of the resin layer on the front surface of the double-sided copper-clad glass epoxy substrate 10 shown in FIG. The state in which the circuit pattern (13B ') of the resin layer is formed is shown.

Subsequently, as shown in FIG. 1E, etching is performed using the circuit patterns (13A ') and (13B') of the resin layer as an etching resist to form a copper foil (12A),
The part other than the exposed circuit pattern of (12B) is dissolved and removed. By this etching, copper foil circuit patterns (12A ') and (12B') are formed below each of the resin layer circuit patterns (13A ') and (13B').
As the etchant, for example, ferric chloride, cupric chloride, or the like is used.

Subsequently, the circuit pattern (13
A ') and (13B') are removed, and as shown in FIG. 1 (f), a printed wiring having copper foil circuit patterns (12A ') and (12B') formed on the front and back of a glass epoxy (11). Get the board. As a chemical solution for removing the circuit pattern of the resin layer, a solvent that dissolves the used resin or a solvent that swells, an alkaline aqueous solution, an acidic aqueous solution, or the like is used.

As described above, according to the method for forming a circuit on a printed wiring board according to the present invention, defects in a circuit pattern caused by dust during exposure can be reduced, and fluctuations in the line width of the circuit pattern can be eliminated. The development step in the conventional method is unnecessary, and the efficiency of drawing and forming a circuit pattern by a laser beam can be improved.

FIGS. 2A to 2L are partial sectional views showing an example of a circuit forming method for a printed wiring board according to the second aspect. As shown in FIG. 2A, as a substrate, for example, a copper foil (22A) on the front and back of a glass epoxy (21),
As shown in FIG. 2B, a through hole (29) for a through hole is provided in this double-sided copper-clad glass epoxy substrate (20) to which (22B) is attached. . The substrate may be a multilayered substrate in advance.

Next, a double-sided copper-clad glass epoxy substrate (2
B) mechanical polishing is performed on both sides to remove burrs generated when the through-holes (29) are provided, and then both sides of the double-sided copper-clad glass epoxy substrate (20) and the through-holes (29) have a thickness of 0.2 mm.
Electroless plating of about μm to 2.0 μm and thickness of 5.0 μm
m to 35 μm electrolytic plating, and the first copper layer (2
Form 3). (FIG. 2 (c)). When using a multi-layered base material in advance, if resin is present on the copper foil on the side surface of the through hole in the inner layer, poor connection of the copper foil is likely to occur. The inside of the through-hole is washed using, for example, to remove the resin.

Next, as shown in FIG. 2D, a resin layer (25) is provided on both sides and through holes of the double-sided copper-clad glass epoxy substrate on which the first copper layer is formed, and as shown in FIG. like,
The circuit pattern portion and the through-hole portion of the resin layer on the surface side of the double-sided copper-clad glass epoxy substrate are removed by drawing using a laser beam (24), and the first circuit pattern portion and the through-hole portion of the first copper layer are removed. Exposing the copper layer. Similarly, the circuit pattern portion and the through-hole portion of the resin layer on the back side are removed by drawing using a laser beam to expose the circuit pattern portion of the first copper layer and the through-hole portion of the first copper layer. (Figure 2
(F)). At this time, the method of providing the resin layer (25), the material of the resin layer, the method of removing the resin layer using the laser beam (24), the type of laser, the wavelength of the laser beam, the beam diameter of the laser beam, and the like are as follows. This is the same as that of the embodiment.

Next, the exposed circuit patterns (23A) and (23B) of the first copper layer and the through-hole portion (23C) are formed as follows:
A second copper layer (26) having a thickness of about 5.0 μm to 30 μm is formed by electrolytic plating. As shown in FIG. 2 (g), the second copper layer (26) is a circuit pattern (26A) of the second copper layer.
On the circuit pattern (23A) of the first copper layer on the front side of the double-sided copper-clad glass epoxy board, and on the circuit pattern (23B) of the first copper layer on the back side as the circuit pattern (26B) of the second copper layer. Is formed on the through-hole portion (23C) of the first copper layer as a through-hole portion (26C) of the second copper layer.

Next, a metal layer resistant to an etching solution is formed as an etching resist on the second copper layer (26) by electrolytic plating. Gold, solder alloy,
Nickel tin or the like can be used, but practical solder alloys are often used, and the thickness is about 5.0 μm to 20 μm. As shown in FIG. 2 (h), the solder alloy layer (2
7) are on the circuit pattern (26A) of the second copper layer on the front side of the double-sided copper-clad glass epoxy board, on the circuit pattern (26B) of the second copper layer on the back side, and through-hole portions of the second copper layer ( 26
C) on top.

Next, as shown in FIG. 2I, the resin layer (25) is removed, exposing the first copper layer (23). Thus, the circuit pattern (26A) of the second copper layer and the solder alloy layer (27) are placed on the first copper layer (23) on the front side of the double-sided copper-clad glass epoxy board, and the first copper layer (23) on the back side. The circuit pattern (26B) of the second copper layer and the solder alloy layer (2)
7) is obtained by forming the through-hole portion (26C) of the second copper layer and the solder alloy layer (27) on the first copper layer (23) of the through-hole portion. As a chemical solution for removing the resin layer which is a portion other than the circuit pattern, a solvent for dissolving the used resin,
Alternatively, a swelling solvent or the like is used.

Next, as shown in FIG. 2 (N), etching is performed using the solder alloy layer (27) as an etching resist, and a portion of the first copper layer (23) other than the circuit pattern and the copper foil (22A), The part other than the circuit pattern of (22B) is dissolved and removed. By this etching, the solder alloy layer (2
7, the circuit patterns (23A), (23) of the first copper layer, respectively, in addition to the circuit patterns (26A), (26B) of the second copper layer already formed as circuit patterns.
B), and copper foil circuit patterns (22A '), (22
B ′) is formed. Further, below the through-hole portion of the solder alloy layer, a through-hole portion (23C) of the first copper layer is formed in addition to the already formed through-hole portion (26C) of the second copper layer. In addition, as an etching solution, for example, ferric chloride, cupric chloride, or the like is used.

Next, the solder alloy layer (27) is removed, and FIG.
As shown in (l), a circuit pattern (22A ') of a copper foil, a circuit pattern (23A) of a first copper layer, and a circuit pattern (26A) of a second copper layer are formed on the surface side of the glass epoxy (11).
A circuit pattern (22B ′) of a copper foil and a circuit pattern (23) of a first copper layer are formed on the back side.
B), a circuit pattern composed of a circuit pattern (26B) of the second copper layer is formed, and a through hole portion is composed of a through hole portion (23C) of the first copper layer and a through hole portion (26C) of the second copper layer. A printed wiring board having a through hole is obtained.
Note that the solder alloy layer serving as an etching resist does not have to be removed.

As described above, according to the circuit forming method for a printed wiring board according to the second aspect, even in a printed wiring board having a through hole, defects in a circuit pattern caused by dust during exposure can be reduced. Variations in the line width of the circuit pattern can be eliminated, and the development step in the conventional method can be made unnecessary, so that the efficiency of drawing and forming the circuit pattern by laser light can be improved.

[0031]

According to the present invention, when a circuit is formed on a copper-clad laminate, a resin layer is first provided on the copper surface of the copper-clad laminate, and portions other than the circuit pattern of the resin layer are formed by using a laser beam. Removed to expose the copper in the parts other than the circuit pattern, form the circuit pattern of the resin layer, and then use the circuit pattern of the resin layer as an etching resist to dissolve the copper in the parts other than the exposed circuit pattern by etching. Since the circuit pattern of the printed wiring board is formed by removing the circuit pattern of the resin layer, the defects of the circuit pattern due to dust generated at the time of exposure are reduced, and the line width of the circuit pattern is eliminated, and furthermore, Is a method for forming a circuit of a printed wiring board, which can shorten a circuit forming process, shorten an exposure time, and form a circuit at low cost.

Further, according to the present invention, when a circuit is formed on a copper-clad laminate, a through hole for a through-hole is first provided in the double-sided copper-clad laminate, and the first and second through-holes are formed on both sides and the through-hole of the double-sided copper-clad laminate. A copper layer is formed, a resin layer is provided, a circuit pattern portion and a through-hole portion of the resin layer are removed using a laser beam, and then a second circuit pattern portion and a through-hole portion of the exposed first copper layer are formed. Forming a copper layer, forming a metal layer resistant to an etchant, removing the resin layer to expose the first copper layer, and subsequently using the metal layer as an etching resist to expose the first copper layer and both surfaces Dissolve and remove the copper in the copper clad laminate by etching,
Since the circuit of the printed wiring board is formed by removing the metal layer, in forming the circuit of the printed wiring board having through holes, defects of the circuit pattern due to dust generated during exposure are reduced, and A circuit forming method for a printed wiring board is provided which eliminates variations in line width, shortens circuit forming steps, shortens exposure time, and enables circuit formation at low cost.

Further, according to the present invention, in the method for forming a circuit of a printed wiring board, the laser light may be 20 μm to 10 μm.
Since a plurality of laser beams having a beam diameter of 0 μm are selectively used, the peripheral portion of the circuit pattern is made smooth, and the efficiency of drawing removal is improved.

Further, according to the present invention, there is provided the circuit forming method for a printed wiring board, wherein the laser beam has a wavelength of 1321n.
Since a laser beam having a wavelength of m to 193 nm is used, no resin residue is left on the copper foil under the resin layer due to the thermal processing by the CO2 laser.

[Brief description of the drawings]

FIGS. 1A to 1F are partial sectional views showing one embodiment of a method for forming a circuit on a printed wiring board according to the present invention.

FIGS. 2A to 2L are partial cross-sectional views illustrating an example of a method for forming a circuit on a printed wiring board according to claim 2;

[Explanation of symbols]

10, 20 double-sided copper-clad glass epoxy board 11, 21 glass epoxy 12A, 12B, 22A, 22B copper foil 12A ', 12B', 22A ', 22B' copper circuit pattern 13A, 13B , 25 ... resin layers 13A ', 13B' ... resin layer circuit patterns 14, 24 ... laser light 22A ', 22B' ... copper foil circuit patterns 23 ... first copper layers 23A, 23B ... Circuit pattern of one copper layer 23C: Through-hole portion of first copper layer 26: Second copper layer 26A, 26B: Circuit pattern of second copper layer 26C: Through-hole portion of second copper layer 27: Solder alloy layer 27A, 27B ... Circuit pattern of solder alloy layer 27C ... Through hole portion of solder alloy layer 29 ... Through hole for through hole

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor, Hirohiro Suzuki 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Atsushi Fukuda 1-5-1, Taito, Taito-ku, Tokyo F-term in Toppan Printing Co., Ltd. (reference) 5E317 AA24 BB01 BB12 CC32 CC33 CC44 CC52 CD15 CD18 CD23 CD25 CD32 GG05 GG09 GG16 5E339 AB02 AD03 AE01 BC02 BD02 BD03 BD08 BD11 BE13 CD01 CD06 CE03 CE12 CE15 CE17 CF06 DD03 FF02 FF02FF

Claims (4)

[Claims] In the formation of a circuit of a printed wiring board, 1) a resin layer is provided on a copper surface of a copper-clad laminate, and 2) a portion other than the circuit pattern of the resin layer is removed by using a laser beam. Exposing the copper in the portion other than the circuit pattern to form a circuit pattern of the resin layer; 3) using the circuit pattern of the resin layer as an etching resist, dissolving and removing the copper in the portion other than the exposed circuit pattern by etching; 4) A circuit forming method for a printed wiring board, wherein a circuit pattern is removed from the resin layer to form a circuit on the copper-clad laminate. 2. In forming a circuit of a printed wiring board, 1) providing a through hole for a through hole in a double-sided copper-clad laminate;
A first copper layer is formed on both sides and through holes of the double-sided copper-clad laminate by electroless plating and electrolytic plating. 2) A resin layer is formed on both sides and the through-holes of the double-sided copper-clad laminate on which the first copper layer is formed. Providing, removing the circuit pattern portion and the through hole portion of the resin layer by using a laser beam, exposing the first copper layer of the circuit pattern portion and the through hole portion; 3) the exposed circuit pattern portion of the first copper layer And a second copper layer is formed on the through-hole portion by electrolytic plating. 4) A metal layer resistant to an etching solution is formed on the second copper layer by electrolytic plating. 5) The resin layer is removed. 6) dissolving and removing the exposed first copper layer and copper of the double-sided copper-clad laminate by etching using the metal layer as an etching resist; and 7) removing the metal layer. Forming circuits with through holes in double-sided copper-clad laminates Circuit formation method of the printed wiring board, wherein Rukoto. 3. The laser beam as claimed in claim 1, wherein the laser beam has a thickness of 20 μm to 100 μm.
3. The method for forming a circuit on a printed wiring board according to claim 1, wherein a plurality of laser beams having a beam diameter of m are selectively used. 4. The method according to claim 1, wherein the laser beam has a wavelength of 1321 nm or more.
4. The method according to claim 1, wherein a laser beam of 193 nm is used.