JPH11150369A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer printed wiring board where an excellent electrical connection can be made. SOLUTION: A copper foil-attached insulating adhesive film 3 is composed of a copper foil 1 and a semi-cured insulating adhesive layer 2 provided to the roughened surface of the copper foil 1, a hole 4 is bored to serve as a non-through-hole for interlayer connection, the copper foil-attached insulating adhesive film 3 is placed on a previously prepared inner circuit board 5 bringing the insulating adhesive layer 2 into contact with it, a sheet 6 which becomes plastically fluid in a lamination process is laminated on the outer side of the copper foil 1 of the copper foil-attached insulating adhesive film 3 and thermocompressed into one piece, insulating adhesive layer resin 7 oozing out into the hole 4 which serves as a non-through-hole is removed off by laser irradiation, a through-hole 11 is bored, the laminate is subjected to a smear removing treatment, and the inner wall of the non-through-hole 4 is plated to electrically connect the inner circuit 12 and the copper foil 1 together.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art As electronic devices have become lighter, thinner, smaller, and more sophisticated, wiring boards have been required to have higher densities. For this reason, wiring boards have been multi-layered to increase the number of wiring layers, miniaturized to increase the wiring capacity in the same layer, and miniaturized connection holes for connecting between layers.

As a method therefor, Japanese Patent Laid-Open Publication No.
As described in the publication, after a hole is made in advance in a metal foil with an adhesive in which a metal foil and an adhesive of a B stage are integrated, the metal foil is laminated and adhered to an inner wiring board on which a wiring is formed, thereby forming a multilayer. As necessary, there is a method of manufacturing a multilayer wiring board with an IVH by forming a through hole, forming a conductor in the hole, and forming a wiring by etching.

Further, a method of forming an insulating resin layer on an inner circuit board, irradiating a laser to a desired position, and then electrically connecting the surface circuit and the inner circuit by copper plating, or a method of forming a copper foil on one side. The insulating adhesive film with copper foil provided with the insulating adhesive layer is laminated and bonded to the inner circuit board, the copper foil at a desired position is etched to form a window hole, and then the insulating resin layer is removed by laser irradiation. A method of electrically connecting a surface circuit and an inner layer circuit by plating is known.

[0005]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. Hei 6-19682
In the case of manufacturing a multilayer wiring board by the method described in Japanese Patent Application Publication, it is necessary to completely fill the wiring portion of the inner wiring board with an adhesive layer of a metal foil with an adhesive. Is preferably small. Therefore, by inserting a sheet or the like flowing at the time of lamination between the laminate and the laminating jig (end plate), the sheet material fills the holes before the flow of the adhesive resin at the time of lamination and the resin is filled. By suppressing the exudation, it is possible to suppress the exudation of the resin into the previously drilled hole. In addition, this method also has an effect of equalizing the pressure on the surface of the laminate, so that the adhesive resin flows into the gaps between the inner wiring layers, and as a result, generation of voids is suppressed.

In such a method for manufacturing a multilayer printed wiring board, when the diameter of the non-through hole is large, the seepage of the resin of the insulating adhesive layer is small, or the seepage using the plastic flow sheet is performed. By preventing this, a sufficient electrical connection was possible. However, in a multilayer printed wiring board having a higher density, the hole diameter of the non-through hole is set to, for example, 3
There is a growing demand for the thickness to be less than 00 μm,
With such a small hole diameter, it is not sufficient to prevent the insulative adhesive layer from seeping out by the plastically flowing sheet, and it is impossible to make a sufficient electrical connection.

Further, in a method of forming an insulating resin layer on an inner circuit board, irradiating a desired position with a laser, and thereafter electrically connecting the surface circuit and the inner circuit by copper plating, a method of forming an insulating resin layer on the inner circuit board is described. Since the adhesion to the plated copper is weak, the heat resistance is low. In order to improve this, an insulating adhesive film with copper foil provided with an insulating resin layer on one side of the copper foil is laminated and bonded to the inner layer circuit, the copper foil at the desired position is etched to form a window hole, and then There is a method of removing the insulating resin layer by laser irradiation and electrically connecting the surface circuit and the inner layer circuit by plating. However, since a window hole must be formed for each individual panel, the dimensions of the negative when forming the circuit There has been a problem of variation in the position of the window hole due to the change, and poor electrical connection due to the poor formation of the window hole due to residual development.

The present invention provides a method for manufacturing a multilayer printed wiring board having excellent electrical connection.

[0009]

The method of manufacturing a multilayer printed wiring board according to the present invention is directed to a method of manufacturing an insulating adhesive film with a copper foil having a semi-cured insulating adhesive layer provided on a roughened surface of a copper foil. ,
A hole 4 serving as a non-through hole for interlayer connection is opened, and the insulating adhesive film 3 with copper foil is overlapped so that the insulating adhesive layer 2 is in contact with an inner circuit board 5 prepared in advance. A sheet 6 that plastically flows in the laminating process is superimposed on the outer side of the copper foil 1 of the adhesive film 3, laminated by laminating by heating and pressing, and the insulating adhesive layer resin 7 leached out into the hole 4 to be a non-through hole. After removing by laser irradiation and drilling the through hole 11, smearing is performed, and plating is performed on the inner wall of the hole 4 to be a non-through hole to electrically connect the inner layer circuit 12 and the copper foil 1. It is characterized by the following.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Copper Foil) As the copper foil 1 used for the insulating adhesive film 3 with a copper foil of the present invention, an electrolytic copper foil or a rolled copper foil having a thickness of 5 μm to 70 μm can be used.
When the thickness is less than 5 μm, the handleability is poor, and
If it exceeds 0 μm, the accuracy of etching the copper foil is reduced. When a thin copper foil having a thickness of 5 μm is used, a material supported by a carrier layer can be used to improve the handleability.

(Insulating Adhesive) The semi-cured insulating adhesive layer used in the present invention comprises a halogenated high molecular weight epoxy polymer having a molecular weight of 100,000 or more, a crosslinking agent, and a polyfunctional epoxy resin. A thermosetting epoxy resin composition as a constituent component can be used. This molecular weight is 100,
000 or more halogenated high molecular weight epoxy polymer, difunctional epoxy resin and halogenated bifunctional phenols,
Epoxy group / phenolic hydroxyl group = 1 / 0.9-1 /
1.1, in the presence of a catalyst, in an amide-based or ketone-based solvent having a boiling point of 130 ° C. or more, a reaction solid concentration of 50% by weight.
Below, it obtains by heating and superposing | polymerizing. As the cross-linking agent, masked isocyanates obtained by masking (blocking) isocyanates with a compound having another active hydrogen can be used. As the polyfunctional epoxy resin, any compound having two or more epoxy groups in a molecule may be used, and a phenol type epoxy resin, an alicyclic epoxy resin, an epoxidized polybutadiene, a glycidyl ester type epoxy resin, A glycidylamine type epoxy resin, an isocyanurate type epoxy resin, a flexible epoxy resin, or the like can be used.

(Insulating Adhesive Film with Copper Foil) In order to provide this thermosetting epoxy resin composition as a semi-cured insulating adhesive layer on the matte side of a copper foil, the above-mentioned molecular weight of 100,000 is required. The above-mentioned halogenated high molecular weight epoxy polymer, a cross-linking agent, and a polyfunctional epoxy resin are mixed to form an adhesive varnish, a blade meter, a knife coater, a squeeze coater, and the like, a post-metering system coating method, a reverse roll coater, and a kiss. Roll coater, cast coater,
It is applied by a pre-metering coating method such as a spray coater or an extrusion coater, and the resin is semi-cured while evaporating the solvent.

Further, the adhesive varnish is coated on a support film such as a polyethylene terephthalate film, the resin is semi-cured while evaporating the solvent, and the support film is peeled off. It can be attached to the surface, and it can be applied more than twice.
It can also be formed by drying or using two or more film-forming adhesives.

(Drilling of non-through holes) Drilling of the insulating adhesive film with copper foil is performed by drilling or punching with a die. In drilling, five or more holes can be drilled, depending on the thickness of the copper foil.

(Plastic Flowing Sheet) In the present invention, in the step of applying pressure and heating and laminating and integrating the insulating adhesive film with copper foil, in order to prevent the opening of the holed insulating adhesive film with copper foil, On the copper foil, a sheet that plastically flows in the process of further pressing and heating and laminating and integrating is performed, and the sheet that plastically flows in the process of pressing and heating and laminating and integrating, It is preferable to use one having a three-layer structure composed of a layer and an outer layer sandwiching the core layer from both sides, and having a softening point of the core layer of 130 ° C. or less.

According to this method, before the insulative adhesive layer resin of the insulative adhesive film with copper foil starts to flow, the sheet that plastically flows in the above-mentioned step of heating under pressure and laminating and integrating firstly flows. Since the flow starts and flows into the holes formed in the insulating adhesive film with a copper foil and closes the holes, the hole closing due to the flow of the insulating adhesive layer resin itself is suppressed.

The sheet which plastically flows in the process of laminating and integrating by pressurizing and heating must of course be one which can be easily peeled and removed after laminating and integrating.

The three-layer film suitable for this purpose has a three-layer structure comprising a core layer and an outer layer, wherein the core layer is lower than the softening point of the insulating adhesive of the insulating adhesive film with copper foil. Preferably 130 ° C. or less, more preferably 1 ° C.
A thermoplastic resin sheet such as polyethylene, ethylene-based copolymer, vinyl-based polymer, acrylic-based polymer, aliphatic polyester or polyamide having a temperature of 15 ° C. or less is used for the core, and the outer layer is made of a fluorine-based polymer or silicon-based material having excellent releasability. It is preferable to use polymers and high-strength polyolefins.

(Inner Circuit Board) As the inner circuit board of the present invention, a glass epoxy copper-clad laminate, a paper phenol copper-clad laminate, a composite copper-clad laminate, a polyimide copper-clad laminate, or the like can be used. After drilling through holes in these copper-clad laminates, copper plating is performed, and unnecessary portions of copper are removed by etching, whereby an inner wiring board having through holes can be manufactured.
Further, the method is not necessarily limited to such a method, and a hole is formed in an insulating substrate containing a plating catalyst therein or a substrate having an electroless plating adhesive applied to the surface of the insulating substrate to form a circuit. An inner layer plate having a through hole, which is produced by forming a plating resist in a portion where it is not formed and performing plating, can also be used.

(Removal of Insulating Adhesive Layer Resin) The removal of the insulating adhesive layer resin that has oozed into the non-through hole is performed by laser irradiation. Laser irradiation conditions vary depending on the type of resin used for the insulating adhesive layer.
It is determined experimentally in advance depending on the kind of the insulating adhesive layer resin to be used. Furthermore, the laser irradiation conditions are set in consideration of the close relationship between the degree of the influence of the residue of the insulating adhesive layer resin on the connection reliability and the conditions of the treatment with an alkaline permanganate solution described later. There is a need to. This must also be determined experimentally. As the laser for irradiation, a YAG laser can be used in addition to the CO ₂ laser.

(Smear treatment) After the resin of the insulating adhesive layer is removed by laser irradiation, resin residue of a thin film is generated on the surface of the inner copper foil. Therefore, in order to improve connection reliability, it is necessary to perform smear treatment. I need. As a solution used for the smear treatment at this time, an alkaline permanganate solution can be used. It can be removed even with a processing solution such as chromic acid. In any case, a neutralization treatment is required thereafter.

As the treatment solution with the alkaline permanganate solution and the neutralization treatment solution, a commercially available smear treatment solution is sufficient, and a solution containing a resin swelling agent in the initial step of smear treatment is desirable. As such a swelling agent, there is an aqueous solution containing an alcohol-based solvent. The treatment solution of the alkaline permanganate solution is sodium permanganate: 50 to 7
The desired effect can be obtained in the range of 0 g / l and the concentration of sodium hydroxide: 30 to 50 g / l. Examples of the neutralizing solution include hydroxylamine hydrochloride, hydroxylamine sulfate, hydrazine sulfate, tin (II) chloride, and the like.
A range of 0.01 to 0.2 ml / l is preferred.

After the removal of the insulating adhesive layer resin by laser irradiation, the solubility of the resin residue of the thin film formed on the surface of the inner copper foil in the smear treatment solution decreases due to the difference in the type of the insulating adhesive layer resin. And in such cases,
By performing the smear treatment twice or more, the resin residue due to the laser irradiation can be more favorably removed.

(Removal of Resin Residue by Excimer Laser) After the resin of the insulating adhesive layer is removed by laser irradiation, and before the treatment with an alkaline permanganate solution, the insulating property after the laser irradiation is further increased by using an excimer laser. If the residue of the adhesive layer resin is removed, the number of treatments with the alkaline permanganate solution can be reduced.

[0025]

EXAMPLE 1 As shown in FIG. 1 (a), as an insulating adhesive film 3 with a copper foil, an epoxy insulating adhesive having a thickness of 50 μm was applied to a roughened surface of a copper foil having a thickness of 18 μm. , Semi-cured M
CF-3000E (trade name, manufactured by Hitachi Chemical Co., Ltd.)
Prepare The insulating adhesive was drilled into a hole having a diameter of 0.3 mm, then vacuum-pressed on a 1.6 mm-thick copper-clad laminate under the condition of 25 kgf / cm ² , laminated and bonded, and leached into the hole. The distance is about 80 μm. A non-penetrating hole 4 having a diameter of 0.25 mm was drilled in the insulating adhesive film 3 with a copper foil. Next, the thickness 18
Unnecessary copper foil of a glass epoxy double-sided copper-clad laminate having a thickness of 0.6 mm, in which a copper foil of μm is laminated on both sides, is etched away to produce an inner layer circuit board 5 on which a circuit is formed. The above-mentioned insulating adhesive film 3 with a copper foil is laid so that the insulating adhesive layer 2 is in contact with the inner circuit board 5, and the copper foil 1 of the insulating adhesive film 3 with a copper foil is further laminated.
As a sheet 6 that flows plastically, an opulan sheet (trade name, manufactured by Mitsui Petrochemical Industry Co., Ltd.) having a core layer thickness of 90 μm, an outer layer on both sides of 30 μm and a three-layer structure of 150 μm thickness is used. 1. Stack, temperature 170 ° C, pressure 2.
After pressurizing and heating at 5 MPa for 60 minutes to laminate and integrate, the plastically flowing sheet 6 was peeled off to produce a multilayer board shown in FIG. 1 (b). Next, as shown in FIG. 1 (c), the insulating adhesive layer resin 7 leached into the non-through holes is removed by a laser processing machine GS-500 (trade name, manufactured by Sumitomo Heavy Industries, Ltd.). Laser irradiation was performed under the conditions of an energy intensity of 20 KV, a pulse width of 1 μs, and the number of shots was 5 shots. Next, as shown in FIG. 1 (d), a through-hole 11 having a diameter of 0.3 mm was drilled, and further an alkaline permanganate solution (potassium permanganate 60 g / l, sodium hydroxide concentration 40 g / l). Immersion treatment at a liquid temperature of 60 ° C. for 3 minutes, followed by a neutralizing solution, Enplate MLB4
98 (manufactured by Meltex Co., Ltd., trade name) at a liquid temperature of 20 ° C
For 5 minutes, and the treatment with the alkaline permanganate solution and the treatment with the neutralizing solution were performed again. Thereafter, as shown in FIG. 1E, copper plating 13 having a thickness of 12 μm is performed, copper in unnecessary portions is etched to form an outer wiring, and a high-density multilayer having a non-through hole in a surface layer is formed. A printed wiring board was manufactured. In this multilayer printed wiring board, the size of the non-through hole is such that the diameter of the opening is 0.23 mm, the diameter of the bottom is 0.18 mm, and (260 ° C. hot oil immersion for 10 seconds) / (20 ° C
Immersion in water for 20 seconds), the electrical resistance is still 1 after a 50-cycle hot oil test.
It did not rise by 0%. Further, in the MIL-107 test, one cycle of (air cooling at −65 ° C. for 30 minutes) / (air heating at 125 ° C. for 30 minutes) is 20 cycles.
Even after the 0-cycle test, the increase in electrical resistance is 1
It did not exceed 0%.

Example 2 After removing the insulating adhesive layer resin 7 leached into the non-through hole by laser irradiation, the excimer laser processing machine NLE-1 was used.
A21 / 10C (Hitachi Seiko Co., Ltd., trade name)
A multilayer printed wiring board was obtained in the same manner as in Example 1 except that irradiation with an excimer laser (average output: 50 W, scan speed: 200 mm / min) was performed. In this multi-layer printed wiring board, even after a test of 50 cycles in a hot oil test in which (soaked in hot oil at 260 ° C. for 10 seconds) / (soaked in water at 20 ° C. for 20 seconds), the electric resistance was maintained. Did not rise by 10%. Also,
MIL-1 having a cycle of (air cooling at −65 ° C. for 30 minutes) / (air heating at 125 ° C. for 30 minutes) as one cycle.
In the 07 test, the increase in the electric resistance did not exceed 10% even after performing the test for 200 cycles.

Example 3 As an insulating adhesive film 3 with a copper foil, an epoxy insulating adhesive having a thickness of 50 μm was applied to a roughened surface of a copper foil having a thickness of 18 μm to form a semi-cured MCF-3000E [HF ]
A multilayer printed wiring board was obtained by performing the same operation as in Example 1 except that (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used.
In this multilayer printed wiring board, (immersion in hot oil at 260 ° C. for 10 seconds) / (immersion in water at 20 ° C. for 20 seconds) is 1
The electrical resistance did not increase by 10% even after performing the 50-cycle test in the hot oil test as a cycle. Also, (air cooling at −65 ° C. for 30 minutes) /
In the MIL-107 test in which one cycle (heating in the air at 125 ° C. for 30 minutes) was performed for one cycle, the increase in electric resistance did not exceed 10% even after performing the test for 200 cycles.

COMPARATIVE EXAMPLE 1 The same operation as in Example 1 was performed except that laser irradiation was not performed and the leached insulating adhesive layer resin was not removed. A multilayer printed wiring board was obtained. In this multilayer printed wiring board, the size of the non-through hole is such that the diameter of the opening is 0.23 mm, the diameter of the bottom is 0.05 mm, and (immersion in hot oil at 260 ° C. for 10 seconds) / (20 In a hot oil test with 1 cycle of immersion in water at 20 ° C. for 20 seconds, the wire was disconnected after 20 cycles of the test.

[0029]

As described above, according to the method for manufacturing a multilayer printed wiring board of the present invention, good connection reliability can be obtained.
High-density multilayer printed wiring boards having non-through holes in the surface layer can be manufactured.

[Brief description of the drawings]

FIGS. 1A to 1E are cross-sectional views illustrating respective manufacturing steps of a multilayer printed wiring board according to an embodiment of the present invention.

[Explanation of symbols]

1. Copper foil 2. 2. Insulating adhesive layer 3. Insulating adhesive film with copper foil 4. Holes that become non-through holes Inner layer circuit board 6. 6. Plastically flowing sheet 10. Insulating adhesive layer resin Through hole 12. Inner layer circuit 13. Copper plating

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihiro Tamura 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Inside the Shimodate Plant of Hitachi Chemical Co., Ltd. (72) Koichi Tsuyama 1500 Oji Ogawa Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Inside the Shimodate Factory (72) Inventor Tomi Ujiya 1500 Ogawa, Oji, Shimodate City, Ibaraki Prefecture Inside the Shimodate Factory, Hitachi Chemical Co., Ltd. (72) Kunio Kawaguchi 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture, Shimodate Factory, Hitachi Chemical

Claims (6)

[Claims] A non-through hole for interlayer connection is formed in an insulating adhesive film with copper foil provided with a semi-cured insulating adhesive layer on a roughened surface of the copper foil. A hole (4) is formed, and the insulating adhesive film with copper foil (3) is overlapped so that the insulating adhesive layer (2) is in contact with the prepared inner layer circuit board (5). On the outside of the copper foil (1) of the adhesive film (3), a sheet (6) that plastically flows in the laminating process was overlaid, laminated by laminating by heating and pressurizing, and leached into the hole (4) to be a non-through hole The insulating adhesive layer resin (7) is removed by laser irradiation, and the through-hole (1) is removed.
After drilling 1), perform smearing, and plating the inner wall of the hole (4), which will be a non-through hole, with the inner layer circuit (12) and copper foil
(1) A method for producing a multilayer printed wiring board, wherein the method is electrically connected to (1). 2. A thermosetting thermosetting resin composition comprising a halogenated high molecular weight epoxy polymer having a number average molecular weight of 100,000 or more, a crosslinking agent, and a polyfunctional epoxy resin as an insulating adhesive layer (2). The method for producing a multilayer printed wiring board according to claim 1, wherein an epoxy resin composition is used. 3. The non-through hole (4) has a hole diameter of 300 μm.
3. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein m is equal to or less than m. 4. 4. A sheet (6) plastically flowing in the laminating process.
Has a three-layer structure consisting of a core layer and an outer layer sandwiching the core layer from both sides, and the softening point of the core layer is 130 ° C. or lower, wherein the core layer has a softening point of 130 ° C. or less. Of manufacturing a multilayer printed wiring board. 5. Insulating adhesive layer resin by laser irradiation (7)
The method for producing a multilayer printed wiring board according to any one of claims 1 to 4, wherein excimer laser irradiation is further performed after the removal. 6. Insulating adhesive layer resin by laser irradiation (7)
The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 5, wherein the smear treatment after the removal is performed twice or more.