JP2003273497A - Transfer sheet and method of manufacturing the same, and wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the problem that it has been impossible to form a fine circuit pattern by a transfer sheet that transfers a metal layer formed in a shape of the circuit pattern on an insulation layer to form a conductor circuit. <P>SOLUTION: A metal layer 2, which is formed in the shape of the circuit pattern on a substrate 1 of a transfer sheet 5, is transferred to an insulation layer 3 for the formation of a conductor circuit 4. At least a portion of the circuit pattern of the metal layer 2 is laser-processed. Since the metal layer of fine portions of the conductor circuit 4 can be removed by radiating laser light having a fine beam diameter without etching or plating, it has become possible to form the fine conductor 4 having a width or pitch of 50 μm or below. As a result, the disconnection of the conductor circuit 4 due to over etching and imperfect deposition, or a short in the conductor circuit 4 due to the remain of the etching or a short in plating are prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer sheet for forming a conductor circuit such as a wiring board or a package for accommodating semiconductor elements, a method for manufacturing the transfer sheet, a wiring board manufactured by using the transfer sheet, and a method for manufacturing the wiring board. Regarding

[0002]

2. Description of the Related Art Conventionally, as a high-density wiring board, for example, a high-density multilayer wiring board used for a package for housing semiconductor elements, a printed circuit board made of an organic resin has been widely used. In this printed board, a conductor circuit is formed by a method of etching a copper foil after adhering a copper foil to the surface of an insulating layer made of an organic resin such as an epoxy resin, or by forming a conductive circuit on the surface of the insulating layer. It is manufactured by stacking these insulating layers to form a multilayer structure.

However, in the method of adhering a copper foil to the surface of the insulating layer and removing the unnecessary copper foil portion by etching, or forming a conductor circuit on the surface of the insulating layer by a plating method, the insulating layer is an etching solution. There is a problem that the characteristics of the insulating layer are changed by coming into contact with a chemical such as a plating solution or the like. In addition, since the conductor circuit is only placed on the surface of the insulating layer, there is a problem that the conductor circuit may not adhere to the insulating layer and a void may occur at the interface between the copper foil and the insulating layer. Was. Further, there is a problem that the flatness of the insulating layer is lowered due to the convex portion formed by the conductor circuit even when the insulating layer is formed in multiple layers.

In order to solve such a problem, a transfer sheet having a conductor circuit formed by a method of adhering a metal foil on a support and then etching the metal foil or by plating on the support is manufactured. After that, a method of transferring the conductor circuit of the transfer sheet to the insulating layer has been proposed.

In the method of transferring such a conductor circuit, since the conductor circuit is formed on a support by an etching method or a plating method and then the conductor circuit is transferred to an insulating layer, the insulating layer comes into contact with various chemicals. It is excellent in that there is nothing,
Since the conductor circuit is embedded in the insulating layer by the pressure applied when the conductor circuit is transferred, the adhesiveness of the conductor circuit to the insulating layer is excellent and advantageous.

[0006]

In recent years, the density of wiring boards used in multi-layered wiring boards and semiconductor element storage packages has been increasing, and the width and pitch of conductor circuits are 50 μm.
It is now necessary to use fine ones of m or less.

However, when a fine conductor circuit is formed on a transfer sheet by a method using the conventional etching method or plating method as described above, the developing rate of the resist layer used in the etching step or plating step is 50 μm or less. A desired resist pattern cannot be formed because the fine part and the rough part are greatly different, or the adhesion of the resist layer on the fine part is reduced, and the resist layer peels off during the etching process or plating process. Or
Furthermore, since it is very difficult to control the etching rate and the plating deposition rate of the fine portion, excessive etching or plating deposition failure occurs, and as a result, the conductor circuit is broken, or , The conductor circuit is short-circuited due to etching residue or short circuit of plating,
There is a problem that it is difficult to form a fine conductor circuit having a width and a pitch of 50 μm or less.

The present invention has been devised in view of the problems of the prior art, and an object thereof is to provide a transfer sheet having a fine conductor circuit having a width or pitch of 50 μm or less and a wiring board using the transfer sheet. It is in providing.

[0009]

The transfer sheet of the present invention comprises:
Having a metal layer formed in a circuit pattern on the support,
A transfer sheet for transferring this metal layer to the surface of an insulating layer to form a conductor circuit, wherein the metal layer is characterized in that at least a part of a circuit pattern is formed by laser processing. .

Further, the transfer sheet of the present invention is characterized in that, in the above-mentioned constitution, the peripheral portion of the circuit pattern-shaped portion of the metal layer formed by laser processing is projected to the side opposite to the support. is there.

The method for producing a transfer sheet of the present invention comprises a step of forming a metal layer on a support, and a laser irradiation from this metal layer side to remove at least a part of the metal layer to form a circuit pattern. And a step of processing.

The wiring board of the present invention is characterized in that a conductor circuit is formed by transferring the metal layer of the transfer sheet to the surface of the insulating layer.

The method of manufacturing a wiring board according to the present invention comprises a step of superimposing the metal layer side surface of the transfer sheet on the surface of the insulating layer, a step of pressure-bonding the transfer sheet and the insulating layer, and a step of transferring the transfer sheet. And removing the support to transfer the metal layer onto the insulating layer to form a conductor circuit.

According to the transfer sheet of the present invention, since the metal layer is formed by laser processing at least a part of the circuit pattern, it is very difficult to control the etching rate and the plating deposition rate. Since the metal layer can be removed by irradiating with a laser beam having a fine beam diameter without using an etching process or a plating process, it is necessary to form a fine conductor circuit having a width or pitch of 50 μm or less. As a result, the conductor circuit will not be disconnected due to excessive etching or defective deposition of plating, or the conductor circuit will not be short-circuited due to etching residue or plating short circuit.

Further, according to the transfer sheet of the present invention, in the above structure, the peripheral portion of the circuit pattern-shaped portion of the metal layer formed by laser processing is projected to the side opposite to the support. When the metal layer of the sheet is transferred to the insulating layer, the protruding portion of the metal layer is embedded and fixed in the insulating layer, so that the adhesion between the metal layer and the insulating layer can be made strong, and As a result, it is possible to obtain a transfer sheet capable of stably transferring a fine conductor circuit onto an insulating layer without causing transfer failure.

According to the method for producing a transfer film of the present invention, a circuit pattern is formed by forming a metal layer on a support and irradiating a laser from the metal layer side to remove at least a part of the metal layer. Since it is provided with a process for forming a fine conductor circuit, it is possible to form a fine conductor circuit portion with good reproducibility without using an etching process or a plating process using various chemicals that makes microprocessing difficult and unstable. Since the metal layer can be removed by laser processing,
Moreover, it is possible to stably manufacture a transfer sheet having a fine conductor circuit.

According to the wiring board of the present invention, the conductor layer is formed by transferring the metal layer of the above-mentioned transfer sheet to the surface of the insulating layer, so that the wiring board has a width and a pitch of 50 μm or less. A wiring board having a fine conductor circuit can be obtained.

According to the method for manufacturing a wiring board of the present invention, the step of superposing the metal layer side surface of the transfer sheet on the surface of the insulating layer, the step of pressure-bonding the transfer sheet and the insulating layer, and the transfer step The step of removing the support of the sheet and transferring the metal layer onto the insulating layer to form a conductive circuit facilitates the formation of a fine conductive circuit having a width or pitch of 50 μm or less on the insulating layer. It becomes possible to form
Since the conductor circuit is transferred to the insulating layer, the insulating layer does not come into contact with various chemicals, so that the characteristics of the insulating layer are not deteriorated by the chemicals. Further, since the conductor circuit is embedded in the insulating layer by the pressure applied when the conductor circuit is transferred, it is possible to obtain a wiring board having excellent adhesion of the conductor circuit to the insulating layer.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a transfer film of the present invention and a wiring board manufactured using the transfer film will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an example of an embodiment of a transfer sheet of the present invention, and FIGS. 2A to 2C are views for explaining an example of a manufacturing method for producing the transfer sheet of the present invention. 3A to 3C are cross-sectional views of each process.
FIG. 4 is a sectional view of each step for explaining an example of a manufacturing method for manufacturing the wiring board of the present invention using the transfer sheet of the present invention. FIG. 4 shows an example of an embodiment of the wiring board of the present invention. 5A and 5B are sectional views showing an example of another embodiment of the wiring board of the present invention. In these figures, 1 is a support, S is a metal layer, 2 is a metal layer formed in a circuit pattern, 3 is an insulating layer, 4 is a conductor circuit, and is mainly formed in a circuit pattern with the support 1. The transfer sheet 5 of the present invention is composed of the metal layer 2 thus formed, and the wiring board 7 of the present invention is composed mainly of the insulating layer 3 and the conductor circuit 4.

The support 1 constituting the transfer sheet 5 is a support member for processing the metal layer S into a circuit pattern and transferring the metal layer 2 formed in the circuit pattern on the surface of the wiring board 7. A resin film made of polyester, polyethylene terephthalate, polyimide, polyphenene sulfide, vinyl chloride, polypropylene, liquid crystal polymer or the like, or a metal plate made of stainless steel or the like is used.

The thickness of the support 1 is suitably 10 to 500 μm, preferably 20 to 300 μm. If the thickness of the support 1 is less than 10 μm, the support 1 may be deformed or bent, and the metal layer 2 formed in the circuit pattern on the surface tends to cause disconnection, and the thickness exceeds 500 μm. Then, the flexibility of the support 1 is lost, and it tends to be difficult to peel the support 1 from the surface of the wiring board 7.

The transfer sheet 5 also has a metal layer 2 formed in a circuit pattern on the support 1. Such a metal layer 2 is formed of a metal suitable for forming the conductor circuit 4 of the wiring board 7, and for example, a low resistance metal such as gold, silver, copper, aluminum, or an alloy thereof is preferably used.
The thickness is appropriately 1 to 100 μm, preferably 5 to 5
0 μm is preferable. If the thickness of the metal layer 2 is less than 1 μm, the resistivity of the conductor circuit 4 tends to increase, and the thickness of 100 μm
When it exceeds, the deformation of the insulating layer 3 becomes large when the metal layer 2 is transferred onto the insulating layer 3, the amount of the metal layer 2 embedded in the insulating layer 3 becomes large, and the strain of the insulating layer 3 becomes large. The wiring board 7 tends to be easily deformed.

The metal layer S to be the circuit-patterned metal layer 2 is formed by rolling a metal foil, or by a known method such as plating, sputtering, vacuum deposition, ion plating, or coating of a conductive resin film. A thin metal film can be used. In addition, the metal layer S and the support 1
May be adhered with a known adhesive such as acrylic, rubber, silicone, epoxy, etc. The thickness thereof is related to the adhesive strength of the adhesive, but 1 to 20 μm is suitable.

Further, in the transfer sheet 5 of the present invention, the metal layer 2 is formed in a circuit pattern shape, and at least a part of this circuit pattern shape is formed by laser processing. This is important in the present invention.

According to the transfer sheet 5 of the present invention, the metal layer 2
Since at least a part of the circuit pattern is formed by laser processing, it is possible to perform an etching step or a plating step in which it is very difficult to control the etching rate or the plating deposition rate of the fine portion of the conductor circuit 4. Since the unnecessary metal layer S can be removed by irradiating a laser beam having a fine beam diameter without using it,
It becomes possible to form a fine conductor circuit 4 having a width and a pitch of 50 μm or less, and as a result, the conductor circuit 4 is disconnected due to excessive etching or deposition failure of plating, or due to etching residue or plating short circuit. The conductor circuit 4 will not be short-circuited.

Laser processing for forming at least a part of the circuit pattern of the metal layer 2 is performed by YAG.
A laser such as a laser, an excimer laser, a copper vapor laser, a carbon dioxide gas laser, or the like is formed on the metal layer S which is an unnecessary portion,
It can be formed by irradiating from the side and removing the metal layer S. The workability of the metal layer S is good and
From the viewpoint of easily forming the conductor circuit 4 having a fine width or pitch of 50 μm or less, ultraviolet rays such as third harmonic YAG laser, fourth harmonic YAG laser, excimer laser, second harmonic copper vapor laser, etc. It is desirable to use a laser with a wavelength in the region.

As a method of forming the metal layer S in a circuit pattern shape, all may be formed by laser processing, but from the viewpoint of shortening the processing time, the metal layer S other than the fine portion is conventionally formed. After forming by a known photolithography method, only a fine portion may be formed by laser processing. As a manufacturing method thereof, first, as shown in FIG.
After depositing a metal foil to be the metal layer S on the support 1 as shown in the cross-sectional view, as shown in the cross-sectional view in FIG.
A resist layer 8 is formed on the surface of the metal layer S, and the resist layer 8 is formed in a pattern by a conventionally known photolithography method and the exposed metal layer S is removed.
After the resist layer is removed as shown in the cross-sectional view, the fine portion is processed by the laser beam 6, so that the metal layer S can be formed in a circuit pattern.

Further, in the transfer sheet 5 of the present invention,
The peripheral portion of the circuit pattern-like portion formed by laser processing of the metal layer 2 has a protruding portion 2a protruding on the opposite side to the support 1 as shown in the sectional view of the transfer sheet in FIG. It is preferable.

According to the transfer sheet 5 of the present invention, since the peripheral portion of the circuit pattern-shaped portion of the metal layer 2 formed by laser processing is projected to the side opposite to the support 1, the transfer sheet 5 When the metal layer 2 is transferred to the insulating layer 3, the protrusion 2a is embedded and fixed in the insulating layer 3 so that the anchor effect can be increased, so that a fine conductor can be formed without causing a transfer failure. It is possible to stably transfer the circuit 4 onto the insulating layer 3, and as a result, it is possible to obtain the transfer film 5 on which the wiring board 7 having the fine conductor circuit 4 can be manufactured.

From the viewpoint of embedding the protrusion 2a in the insulating layer 3 and improving the adhesion with the insulating layer 3 by the anchor effect to reduce transfer defects, the height of the protrusion 2a is 1 μm. The above is preferable. Also, the metal layer 2
From the viewpoint that the deformation of the insulating layer 3 becomes large when transferred onto the insulating layer 3 and the distortion of the insulating layer 3 is hard to occur.
It is preferably 20 μm or less.

When the metal layer S is formed into a circuit pattern by removing unnecessary portions by laser processing, the peripheral portion of the circuit pattern formed by laser processing is
It is characterized in that a part of the metal layer 2 is melted and deformed by heat melting, and it can be distinguished from the metal layer 2 formed into a circuit pattern by a known etching method.

The protrusion 2a can be formed by thermally deforming the peripheral portion of the circuit pattern portion of the metal layer 2 by adjusting the laser conditions during laser processing. For example, by adjusting conditions such as laser energy, laser pulse frequency, and the number of irradiations, the desired height can be obtained.

By irradiating the metal layer 2 with a laser beam at a constant distance, it is possible to form a linear metal layer 2 having both ends in the width direction formed by laser processing. When the width of the linear metal layer 2 exceeds 50 μm, the cross section in the width direction of the linear metal layer 2 is
The feature is that both ends have protrusions. On the other hand, when the width of the line-shaped metal layer 2 is a fine line of 50 μm or less, the protrusions formed on the peripheral portion of the circuit pattern formed by laser processing are substantially in the width direction of the line-shaped metal layer 2. It is characterized in that it is formed at substantially the same position in the center, and the substantially central portion in the width direction becomes a linear metal layer 2 protruding.

The metal layer 2 is subjected to treatments such as buffing, blasting, brushing, plasma treatment, corona treatment, ultraviolet treatment, chemical treatment, etc. on its surface in order to improve the adhesion with the insulating layer 3 described later. It is preferable to roughen the surface.

Next, the wiring board 7 of the present invention will be described with reference to FIG. 3A to 3C are cross-sectional views for each step for explaining an example of a manufacturing method for manufacturing the wiring board of the present invention using the transfer sheet of the present invention. In this figure, 3a is a precursor sheet which becomes the insulating layer 3.

The insulating layer 3 has a function as a support for the conductor circuit 4 and electronic parts (not shown), and is uncured with epoxy resin, bismaleimide triazine resin, thermosetting polyphenylene ether resin, phenol resin, or the like. Or a semi-cured thermosetting resin, a thermoplastic resin such as a polyimide resin, a fluororesin, a polyphenylene ether resin, a liquid crystal polymer resin, or an aramid resin, or a ceramic green sheet such as alumina or glass ceramic.

When the thermosetting resin is used, the precursor sheet 3a is cured in the heating and curing step, and when the ceramic green sheet is used, the precursor sheet 3a is sintered in the firing step. It becomes the insulating layer 3 that constitutes the wiring board 7 that is finally manufactured.

When the precursor sheet 3a has a porosity of 3 to 40% by volume in a dry state, when the metal layer 2 is transferred and embedded in the precursor sheet 3a, the precursor around the metal layer 2 is formed. The body sheet 3a can be flattened without causing swelling, and the air trapped between the metal layer 2 and the precursor sheet 3a can be easily discharged to prevent the inclusion of bubbles. When the porosity in the dry state exceeds 40% by volume, a large number of precursor sheets 3a are stacked and pressed.
After heating and curing, pores remain in the precursor sheet 3a,
Since the pores may adsorb moisture in the air and reduce the insulating property, it is preferable to set the porosity of the precursor sheet 3a in the dry state to a range of 3 to 40% by volume.

The porosity of the precursor sheet 3a in the dry state is determined by the drying process such as the drying temperature and the heating rate in the drying step when the precursor sheet 3a is formed into a sheet by a known sheet forming method. A desired value can be obtained by appropriately adjusting the conditions.

When the precursor sheet 3a is made of a thermosetting resin or a thermoplastic resin, it is added to the resin material in order to adjust the thermal expansion coefficient of the insulating layer 3 and / or to improve the mechanical strength. Aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate, boric acid Use a filler containing filler such as aluminum, barium stannate, barium zirconate, strontium zirconate, or as a reinforcing material such as glass cloth woven with fibrous glass in a cloth shape or nonwoven fabric of heat resistant organic resin fiber. Organic resin such as epoxy resin and thermosetting polyphenylene ether Those impregnated with, and it is more preferable to use a material obtained by coating the organic resin adhesive layer such as an epoxy resin or a thermosetting polyphenylene ether to the upper and lower surfaces of the heat-resistant film such as a liquid crystal polymer. In particular, from the viewpoint of improving the high-frequency transmission property and / or from the viewpoint of favorably forming the fine through conductor 5 having a diameter of 100 μm or less, the upper and lower surfaces of the liquid crystal polymer film are coated with an organic resin adhesive layer. It is preferable to use the above.

Here, the liquid crystal polymer refers to a polymer having liquid crystallinity in a molten state or a solution state or a polymer having an optical birefringence property, and generally, a lyotropic liquid crystal polymer or a molten polymer exhibiting liquid crystallinity in a solution state. It includes thermotropic liquid crystal polymers that sometimes show liquid crystallinity, or all 1 type, 2 type, and 3 type liquid crystal polymers classified by heat distortion temperature. From the viewpoint of temperature cycle reliability, solder heat resistance, and processability. Therefore, those having a melting point at a temperature of 200 to 400 ° C., particularly at a temperature of 250 to 350 ° C. are preferable.

The precursor sheet 3a is formed by coating the upper and lower surfaces of a heat-resistant film such as a liquid crystal polymer with an organic resin adhesive layer such as epoxy resin or thermosetting polyphenylene ether. In this case, it is manufactured by the following method. First, a liquid crystal polymer film is formed by a well-known inflation method or the like. After the upper and lower surfaces are subjected to surface treatment by plasma treatment or the like, inorganic insulating powder such as silicon oxide having a particle diameter of 0.1 to 15 μm is coated with organic resin such as thermosetting polyphenylene ether resin and solvent / plasticizer.・ A paste obtained by adding a dispersant,
After forming the organic resin adhesive layer using a conventionally known sheet molding method such as the doctor blade method, or by immersing the liquid crystal polymer film in the above paste and pulling it up vertically, the organic resin is applied to the upper and lower surfaces of the liquid crystal polymer film. It is manufactured by forming an adhesive layer and then heating and drying the adhesive layer at a temperature of 60 to 100 ° C. for 5 minutes to 3 hours.

Next, in the method of manufacturing the wiring board 7, first, as shown in the sectional view of FIG.
And (b) the precursor sheet 3a after being aligned.
As shown in cross section in, by stacking them, 1 × 10 ⁶ ~
A pressure of about 5 × 10 ⁷ Pa is applied. At this time, the metal layer 2
To improve the adhesion between the precursor sheet 3a and
It may be heated at ~ 200 ° C. As the precursor sheet 3a, a thermoplastic resin that is softened by heating, a thermosetting resin in a semi-cured state, or a ceramic green sheet is used to embed the metal layer 2 in the precursor sheet 3a by mechanical pressure. be able to.

Then, as shown in the sectional view of FIG. 3C, the precursor 1 is removed by peeling it off or by removing it by a method such as etching.
The wiring layer 7 having the conductor circuit 4 can be manufactured by transferring the metal layer 2 to and then finally heating and curing it.

The wiring board 7 of the present invention has a conductor circuit 4 formed by using the transfer film of the present invention on the upper and lower surfaces of the insulating layer 3 as shown in the sectional view of FIG.
May be Further, it is possible to electrically connect the upper and lower conductor circuits 4 via the penetrating conductor 5 formed in the insulating layer 3. Furthermore, as shown in the sectional view of FIG. 5, the insulating layer 3 having the conductor circuit 4 formed by using the transfer film of the present invention may be multilayered.

The diameter of the through conductor 5 is 20 to 150.
μm, which has a function of electrically connecting the conductor circuits 4 located above and below with the insulating layer 3 interposed therebetween. After the through hole is formed by performing a drilling process on the insulating layer 3 with a laser, It is formed by embedding a conductive paste made of copper, silver, gold, solder or the like in the through hole by a conventionally known screen printing method.

The wiring board 7 of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above-mentioned embodiment, Although the wiring board 7 in which one layer or three layers of insulating layers 3 are laminated is described, the wiring board 7 in which two or four or more insulating layers 3 are laminated to form a multilayered wiring board 7 is also manufactured. Good. Further, the wiring board 7 may be manufactured by laminating one or more insulating layers 3 having the conductor circuits 4 formed by using the transfer sheet 5 of the present invention on the surface of a conventionally known core substrate. Further, a solder resist may be formed on the surface of the wiring board 7 of the present invention.

[0048]

EXAMPLES Next, the transfer sheet and wiring board of the present invention were
The following samples were manufactured and evaluated. (Example 1) An adhesive agent made of an acrylic resin is applied to almost the entire surface of a support made of polyethylene terephthalate having a thickness of 100 µm to make it sticky, and the thickness is 12 µm and the surface roughness Ra is 0.8 µm. Bonded copper foil. Then, after applying a photoresist and performing exposure and development, this was immersed in a ferric chloride solution and the non-patterned portion was removed by etching to form a circuit pattern. The circuit pattern at this point was relatively coarse with a pattern width and pattern interval of 50 μm or more. Further, by irradiating a third harmonic YAG laser on a part of this circuit pattern to remove the copper foil, a fine circuit pattern having a pattern width and a pattern interval of 50 μm or less was formed, and a transfer sheet was manufactured.

In the fine circuit pattern portion, five parallel circuit patterns having a pattern width and a pattern interval of 15 μm and a length of 1 cm were used.

As a result of observing a fine circuit pattern portion on the obtained transfer sheet, a good circuit pattern was formed. Further, as a result of an insulation test in which a voltage is applied between the circuit patterns to measure the insulation resistance, the insulation resistance was not deteriorated due to a short circuit and was good. (Comparative Example 1) The transfer sheet used for Comparative Example 1 does not use the third harmonic YAG laser but uses all the circuit patterns including the fine circuit pattern and the copper foil of the non-patterned portion using the photoresist. It was manufactured in the same manner as the comparative example except that it was formed by etching away.

With respect to the obtained transfer sheet for the comparative example,
As a result of observing the fine circuit pattern part, a non-pattern part remains due to etching defects between the circuit patterns,
A short circuit pattern was found. (Example 2) A transfer sheet was manufactured in the same manner as in Example 1 except that the intensity of the third harmonic YAG laser was adjusted so that the peripheral portion of the fine circuit pattern portion was projected. Next, the transfer sheet is positioned on an insulating film formed by forming a thermosetting polyphenylene ether resin coating layer having a thickness of 20 μm on the upper and lower surfaces of a liquid crystal polymer film having a pressure of 50 μm, or a polyimide film having a thickness of 100 μm. After closely adhering, the support was peeled off to form a conductor circuit made of copper, and finally, heat treatment was performed at a temperature of 200 ° C. for 1 hour under a pressure of 3 MPa to completely cure the wiring to manufacture a wiring board.

Three types of protrusion heights of 0 μm, 5 μm, and 10 μm were prepared for the protrusion height of the peripheral portion of the fine circuit pattern.

As a result of observing a conductor circuit on the obtained wiring board, a wiring board using an insulating film formed by forming a polyphenylene ether resin coating layer on the upper and lower surfaces of a liquid crystal polymer film was found to have a fine circuit pattern peripheral portion. It was found that the circuit pattern was satisfactorily transferred and the fine conductor circuit was satisfactorily formed in any of the protrusion heights. However, in the wiring board using the polyimide film, the protrusion height of the peripheral portion of the fine circuit pattern is 0.
In the case of μm, a transfer failure occurred in the fine circuit pattern portion, and a fine conductor circuit was not formed. On the other hand, it was found that the fine circuit pattern peripheral edge projections of 5 μm and 10 μm were excellent because a good conductor was formed even in a wiring board using a polyimide film.

[0054]

According to the transfer sheet of the present invention, since the metal layer is formed by laser processing at least a part of the circuit pattern, it is very possible to control the etching rate and the plating deposition rate. The metal layer can be removed by irradiating with a laser beam having a fine beam diameter without using a difficult etching process or plating process, thus forming a fine conductor circuit having a width or pitch of 50 μm or less. And as a result,
The conductor circuit will not be broken due to excessive etching or defective deposition of plating, or the conductor circuit will not be short-circuited due to etching residue or plating short circuit.

Further, according to the transfer sheet of the present invention, in the above structure, the peripheral portion of the circuit pattern-shaped portion of the metal layer formed by laser processing is projected to the side opposite to the support, so that the transfer is performed. When the metal layer of the sheet is transferred to the insulating layer, the protruding portion of the metal layer is embedded and fixed in the insulating layer, so that the adhesion between the metal layer and the insulating layer can be made strong, and As a result, it is possible to obtain a transfer sheet capable of stably transferring a fine conductor circuit onto an insulating layer without causing transfer failure.

According to the method for producing a transfer film of the present invention, a step of forming a metal layer on a support and a circuit pattern by irradiating a laser from the metal layer side to remove at least a part of the metal layer. Since it is provided with a process for forming a fine conductor circuit, it is possible to form a fine conductor circuit portion with good reproducibility without using an etching process or a plating process using various chemicals that makes microprocessing difficult and unstable. Since the metal layer can be removed by laser processing,
Moreover, it is possible to stably manufacture a transfer sheet having a fine conductor circuit.

According to the wiring board of the present invention, since the conductor layer is formed by transferring the metal layer of the above-mentioned transfer sheet to the surface of the insulating layer, it has a width and pitch of 50 μm or less. A wiring board having a fine conductor circuit can be obtained.

According to the method for manufacturing a wiring board of the present invention, the step of superimposing the metal layer side surface of the transfer sheet on the surface of the insulating layer, the step of pressure-bonding the transfer sheet and the insulating layer, and the transfer step The step of removing the support of the sheet and transferring the metal layer onto the insulating layer to form a conductive circuit facilitates the formation of a fine conductive circuit having a width or pitch of 50 μm or less on the insulating layer. It becomes possible to form
Since the conductor circuit is transferred to the insulating layer, the insulating layer does not come into contact with various chemicals, so that the characteristics of the insulating layer are not deteriorated by the chemicals. Further, since the conductor circuit is embedded in the insulating layer by the pressure applied when the conductor circuit is transferred, it is possible to obtain a wiring board having excellent adhesion of the conductor circuit to the insulating layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a transfer sheet of the present invention.

2A to 2C are cross-sectional views for each step for explaining an example of a manufacturing method for manufacturing the transfer sheet of the present invention.

3A to 3C are cross-sectional views for each step for explaining an example of a manufacturing method for manufacturing the wiring board of the present invention using the transfer sheet of the present invention.

FIG. 4 is a cross-sectional view showing an example of an embodiment of a wiring board of the present invention.

FIG. 5 is a cross-sectional view showing another embodiment of the wiring board of the present invention.

[Explanation of symbols]

1 ... Support 2 ... Metal layer formed in a circuit pattern 2a ... ・ Projection 3 ... Insulation layer 4 ... Conductor circuit 5 ... Transfer sheet 6 ... Laser light 7 ... Wiring board S: Metal layer

Claims (5)

[Claims] 1. A transfer sheet having a metal layer formed in a circuit pattern on a support, and transferring the metal layer to the surface of an insulating layer to form a conductor circuit, wherein the metal layer is A transfer sheet, wherein at least a part of the circuit pattern is formed by laser processing. 2. The transfer sheet according to claim 1, wherein a peripheral portion of the circuit pattern-shaped portion of the metal layer formed by laser processing projects to the side opposite to the support. 3. A step of forming a metal layer on a support, and a step of irradiating a laser from the side of the metal layer to remove at least a part of the metal layer to form a circuit pattern. A method of manufacturing a transfer sheet, comprising: 4. A wiring board formed by transferring the metal layer of the transfer sheet according to claim 1 or 2 onto the surface of an insulating layer to form the conductor circuit. 5. A step of superimposing a surface of the transfer sheet according to claim 1 on the side of the metal layer on a surface of an insulating layer, a step of pressure-bonding the transfer sheet and the insulating layer, Removing the support of the transfer sheet and transferring the metal layer onto the insulating layer to form the conductor circuit.