JPH088502A - Base for printed wiring board - Google Patents

Abstract

PURPOSE:To provide a metallic base which is used for a printed wiring board having a resin insulating layer and a conductive metallic foil sequentially stacked on the surface of the base, exhibits high adhesiveness with the resin insulating layer and high heat resistance, and does not require attachment of a protection film in etching the conductive metallic foil. CONSTITUTION:A thermally cured resin layer having epoxy resin or epoxy bromide resin as a frame and using phenol resin as a curing agent is provided with a thickness of 10-50mum by burn-curing on a resin insulating layer stacking side of a base. On the opposite side to the resin insulating layer stacking side, a thermosetting polyester resin layer with an average molecular number of not less than 10,000 containing 2-20 pts.wt. of at least one of polyolefin resin and fluorine resin is provided with a thickness of 5-30mum by burn-curing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a printed circuit board which has excellent adhesion and heat resistance, and also has excellent workability for etching a conductive metal foil.

[0002]

2. Description of the Related Art As a base material for a copper-clad printed wiring board, a phenol resin plate, a laminated plate of epoxy resin plate and paper, an epoxy resin plate containing glass fiber, a polyimide resin plate, etc. are widely used. A metal plate is used as a base material of a printed circuit board of a home electric appliance that is equipped with a small motor that emits and dissipates electromagnetic waves such as a VTR and a video camera in consideration of electromagnetic shielding property and strength. There is. In the production of a printed wiring board using such a metal-based substrate, since the metal plate has conductivity, a prepreg or an adhesive obtained by impregnating glass fiber with an insulating resin such as epoxy resin is laminated on one side of the metal plate. Then, an insulating layer is formed and a copper foil is laminated on the insulating layer. These insulating layers and copper foils are laminated on the metal plate at the same time by a thermocompression bonding method.However, in order to improve productivity, the copper foils are stacked in layers and several sets are laminated at the same time. There is.

However, even if a copper foil is directly laminated on the surface of a metal plate with a prepreg or an adhesive by this method, the adhesion between the steel plate and the prepreg or the adhesive is poor and a sufficient adhesive force cannot be obtained. . In particular, when the temperature of the steel sheet rises due to soldering in a solder bath, the adhesion is greatly reduced. In addition, the metal plate is exposed on the opposite side of the printed circuit board and is corroded during the copper foil etching process.To prevent this, a protective film must be attached to the opposite side and peeled after etching. Inferior in sex.

[0004]

Therefore, the present invention provides a substrate for a printed circuit board which is excellent in adhesion and heat resistance, and is also excellent in workability for etching a conductive metal foil such as a copper foil. It is a thing.

[0005]

According to the present invention, a thermosetting resin layer having an epoxy resin or a brominated epoxy resin as a skeleton and a phenol resin as a curing agent is baked and cured on the resin insulating layer laminated side of a substrate. Therefore, the adhesiveness and heat resistance are improved by providing 10 to 50 μm. Further, a number average molecular weight of 10,000, containing 2 to 20 parts by weight of at least one of a polyolefin resin and a fluororesin on the side opposite to the resin insulating layer laminating side of the base material.
By providing a thermosetting polyester resin layer of 0 or more by baking to 5 to 30 μm, etching workability was improved.

[0006]

[Function] A thermosetting resin having an epoxy resin or a brominated epoxy resin as a skeleton and a phenol resin as a curing agent is
Since it has excellent adhesion and heat resistance, when this resin layer is provided on the resin insulation layer laminated side of the base material by bake hardening, it firmly adheres to the base material on both sides and the prepreg (adhesive), and by soldering. Adhesion does not decrease even when heated. This thermosetting resin layer is superior in adhesiveness and heat resistance to the case where the skeletal resin is a polyester resin, an acrylic resin, a polyurethane resin or a melamine resin and the effect agent is an isocyanate or melamine.

In the thermosetting resin layer provided on the opposite side of the base material from the side where the resin insulating layer is laminated, the polyolefin resin and the fluororesin are not easily compatible with the polyester resin. And become unevenly distributed. For this reason, the surface of the resin layer is less likely to be compatible with the polyester resin, and blocking does not occur even when the resin layers of the base material are put together and thermocompression bonded when the copper foil is laminated. Therefore, the thermosetting resin layer remains in a normal state even after the copper foil is laminated,
The base material is not corroded during copper foil etching.

The metal plate used as the base material of the present invention may be any metal plate having rigidity, for example, hot-dip galvanized steel plate, electro-galvanized steel plate, hot-dip aluminum plated steel plate, vacuum-deposited galvanized steel plate, silicon steel plate. , Stainless steel plate, aluminum plate, etc. can be used. Thickness is 0.3
It is preferably ˜1.5 mm. When providing the thermosetting resin layer, a chemical conversion treatment is applied to any of the resin layers. This chemical conversion treatment is a coating type chromate treatment (for example, JP-A-60-50180 and 60-50181).
No.) so that the amount of chromium deposited is preferably ⁵ to 100 mg / m ² . When the amount of deposited chromium is less than 5 mg / m ² , the effect of improving adhesion by the chromate film is small and 100 mg / m ²
Beyond m ^2, chromate - chromium is diffused into the thermosetting resin layer from preparative film, degrading the resin layer. Further, after the chemical conversion treatment, a primer layer may be provided if necessary.

Examples of the polyolefin resin to be added to the thermosetting resin layer provided on the side opposite to the resin insulating layer laminating side of the substrate include polyethylene and polypropylene. These have a molecular weight of 200 to 20,000 and a low molecular weight. Is preferred. Further, as the fluorine resin, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-peroxide
Fluoroalkyl vinyl ether copolymer resin (PF
A), tetrafluoroethylene-ethylene copolymer resin (ETF) and the like. If the content of these polyester resins is less than 2 parts by weight, they sufficiently migrate to the surface of the resin layer and do not become unevenly distributed, so that sufficient blocking resistance cannot be obtained. On the other hand, if it is more than 20 parts by weight, the amount transferred to the surface of the resin layer becomes excessively large, so that the cohesive force of the polyester resin is reduced and the surface layer is missing. If the number average molecular weight of the polyester resin is less than 10,000, the polyester resin is likely to be compatible with the polyolefin resin and the fluororesin, and the transfer thereof to the surface of the resin layer does not occur.

The thickness of the thermosetting resin layer is 10 to 50 μm when it is provided on the resin insulating layer laminated side, and 5 to 30 μm when it is provided on the opposite side. In the former case, the thickness is 10
If it is less than μm, the adhesive strength with the prepreg or the adhesive is reduced, and if it exceeds 50 μm, swelling due to the solvent tends to occur during bake hardening. On the other hand, in the latter case, if it is less than 5 μm, the amount of polyolefin resin or fluororesin in the thermosetting resin layer is small, so the amount transferred to the surface of the resin layer during bake hardening is small and sufficient resistance is obtained. If blocking resistance and etching resistance cannot be obtained and exceeds 30 μm,
On the contrary, since the amount of transfer to the surface of the resin layer during bake hardening becomes excessively large, the cohesive force of the polyester resin decreases and the surface layer is missing. The thermosetting resin layer is formed on a steel sheet by a roll coat method, a spray method, a curtain-float coat method, a die coat method.
The G method may be used.

[0011]

【Example】

Example 1 Coating chrome on a 0.5 mm thick electrogalvanized steel sheet
Pretreatment to obtain a chromium adhesion amount of 50 mg / m ² , and a resin composition obtained by mixing 30 parts by weight of epoxy resin as a skeletal resin and 30 parts by weight of a phenol resin as a curing agent has a dry thickness of 22 μm. Was coated with a roll coater and baked at a steel plate maximum temperature of 230 ° C. for 45 seconds to form a resin layer. Next, two sets of 35 μm-thick copper foil coated with an adhesive having an epoxy resin as a main component are placed on the base resin layer, and two sets are prepared so that the copper foils face each other. Zumishi pressure 100 kg / cm ^2, were laminated by 2 hours of heating under pressure at a temperature 170 ° C..

Example 2 A coating type chrome on a hot-dip galvanized steel sheet having a thickness of 0.8 mm.
Pretreatment so that the amount of deposited chromium is 50 mg / m ² , and a resin composition obtained by mixing 20 parts by weight of a brominated epoxy resin as a skeletal resin and a phenolic resin as a curing agent has a dry thickness of 35 μm. It was coated with a roll coater so that it would be baked and baked at a steel plate maximum attainable temperature of 215 ° C. for 60 seconds to form a resin layer. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

Example 3 A coating type chrome on an electrogalvanized steel sheet having a thickness of 1.0 mm
Pretreatment to obtain a chromium adhesion of 15 mg / m ² , and a resin composition obtained by mixing 30 parts by weight of an epoxy resin as a skeletal resin and a phenolic resin as a curing agent has a dry thickness of 15 μm. Was coated with a roll coater and baked at a steel plate maximum temperature of 240 ° C. for 50 seconds to form a resin layer. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

Example 4 A hot-dip aluminum plated steel sheet having a thickness of 0.8 mm was pretreated by a coating chromate treatment so that the amount of chromium deposited was 80 mg / m ^2, and a brominated epoxy resin as a skeletal resin,
A resin composition prepared by mixing 25 parts by weight of a phenol resin as a curing agent was coated with a roll coater so that the dry thickness was 15 μm, and baked at a steel sheet maximum temperature of 220 ° C. for 50 seconds to form a resin layer. Provided. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

Example 5 A 1.0 mm thick hot-dip aluminum-plated steel sheet was pretreated by coating-type chrome treatment to give a chromium deposition amount of 70 mg / m ^2, and a brominated epoxy resin as a skeletal resin,
A resin composition prepared by mixing 25 parts by weight of a phenol resin as a curing agent was coated with a roll coater to a dry thickness of 25 μm, and baked at a steel plate maximum temperature of 230 ° C. for 50 seconds to form a resin layer. Provided. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

Comparative Example 1 Coating type chrome on a hot-dip galvanized steel sheet having a thickness of 0.5 mm.
Pretreatment to obtain a chromium adhesion amount of 200 mg / m ² , and a resin composition obtained by mixing 30 parts by weight of a polyester resin as a skeletal resin and 30 parts by weight of an isocyanate resin as a curing agent has a dry thickness of 25 μm. Coating with a roll coater and baking at a maximum temperature of 210 ° C for 40 seconds,
A resin layer was provided. Next, Example 1 was formed on the resin layer of this base material.
In the same manner as above, a 35 μm copper foil having the same thickness was laminated.

Comparative Example 2 Coating type chrome on an electrogalvanized steel sheet having a thickness of 0.5 mm
Pretreatment to obtain a chromium adhesion amount of 50 mg / m ² , and a resin composition obtained by mixing 30 parts by weight of an epoxy resin as a skeletal resin and a phenol resin as a curing agent has a dry thickness of 70 μm. Was coated with a roll coater and baked at a steel plate maximum temperature of 220 ° C. for 60 seconds to form a resin layer. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

Comparative Example 3 A coating type chrome on a hot-dip galvanized steel sheet having a thickness of 1.0 mm.
Pretreatment so that the amount of chromium deposited becomes 50 mg / m ² , and a resin composition obtained by mixing 20 parts by weight of a brominated epoxy resin as a skeletal resin and a phenol resin as a curing agent has a dry thickness of 5 μm. It was coated with a roll coater so that the temperature was 230 ° C. and the maximum temperature of the steel sheet was baked for 50 seconds to form a resin layer. Next, a 35 μm-thick copper foil having the same thickness was laminated on the resin layer of the base material in the same manner as in Example 1.

The adhesion, solder heat resistance, oven heat resistance and insulating property between the base material and the copper foil of the printed wiring boards manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 were investigated. The adhesion between the base material and the copper foil was measured by soldering a copper rod having a diameter of 2 mm on the surface of the copper foil, applying a load from the direction perpendicular to the copper rod, and measuring the load at the time of peeling. The solder heat resistance was measured by floating the substrate in a solder bath at 260 ° C. and causing swelling on the surface. Furthermore, the oven heat resistance was measured by the temperature at which swelling occurred on the surface. Further, the insulation is left for 500 hours in an atmosphere of 60 ° C. and 95% relative humidity with a DC voltage of 100 V applied, and then left for 24 hours in an atmosphere of 20 ° C. and 65% relative humidity for a DC voltage of 500 V. The resistance when applying was measured. Table 1 shows the results.
In addition, the adhesion between the base material and the copper foil has a peel strength of 20 N or more, the solder heat resistance has a swelling time of 1 minute or more, and the oven heat resistance has a swelling temperature of 220 ° C. or more. The good performance is 1 × 10 ⁸ Ω or more.

[0020]

[Table 1]

Example 6 Coating chrome on an electrogalvanized steel sheet having a thickness of 0.5 mm
Chromium deposition amount by preparative treatment is pretreated so as to 50 mg / m ^2, a melamine curing agent compounded polyester resin (number average molecular weight: 40,000) in a polyethylene resin (molecular weight: 5,000) and PTFE resin (molecular weight : 2,000
0) were mixed in a total of 4 parts by weight in a total of 8 parts by weight, and the resin composition was coated by a roll coater so that the dry thickness was 20 μm, and baked at a steel plate maximum attainable temperature of 215 ° C. for 45 seconds to form a resin layer Was set up.

Example 7 Coating type chrome on a hot-dip galvanized steel sheet having a thickness of 0.8 mm
Pretreatment to obtain a chromium adhesion of 80 mg / m ² , and 4 weight parts of polyethylene resin (molecular weight: 2,000) to polyester resin (number average molecular weight: 36,000) containing an isocyanate curing agent. The partially mixed resin composition was coated with a roll coater to a dry thickness of 25 μm, and baked at a steel plate maximum attainable temperature of 215 ° C. for 45 seconds to form a resin layer.

Example 8 Coating chrome on a hot-dip galvanized steel sheet having a thickness of 0.8 mm
Pretreatment so that the amount of chromium deposited becomes 45 mg / m ^2, and after coating with polyester resin-based primer-4 μm, the melamine curing agent-containing polyester resin (number average molecular weight: 52,000) was added to the PTFE resin ( Molecular weight: 5.0
00) in 10 parts by weight to prepare a resin composition having a dry thickness of 1
It was coated with a roll coater so as to have a thickness of 0 μm, and baked at a steel plate maximum attainable temperature of 215 ° C. for 45 seconds to form a resin layer.

Example 9 A hot-dip aluminum plated steel sheet having a thickness of 0.8 mm was pretreated by a coating type chrome treatment so that the amount of chromium deposited was 70 mg / m ^2, and a polyester resin containing an isocyanate curing agent ( A resin composition in which a polypropylene resin (molecular weight: 2,000) and a PFA resin (molecular weight: 5,000) were mixed in an amount of 10 parts by weight each with a number average molecular weight of 23,000 and a total of 20 parts by weight, and the dry thickness was 30 μm. Painted with a roll coater so that the maximum temperature reaches 215 ° C.
And baked for 45 seconds to form a resin layer.

Example 10 A 1.2 mm-thick vacuum-evaporated galvanized steel sheet was pretreated by a coating chromate treatment so that the amount of chromium deposited was 15 mg / m ^2, and a polyester resin containing a melamine curing agent A resin composition prepared by mixing 15 parts by weight of a polyethylene resin (molecular weight: 5,000) with an average molecular weight: 35,000 was coated with a roll coater to a dry thickness of 5 μm, and the steel sheet reached the maximum. The resin layer was provided by baking for 45 seconds at a temperature of 215 ° C.

Comparative Example 4 A hot-dip aluminum plated steel sheet having a thickness of 0.8 mm was pretreated by a coating chrome treatment so that the amount of chromium deposited was 200 mg / m ^2, and a polyester resin containing an isocyanate curing agent ( A number average molecular weight: 5,000) was coated with a roll coater so that the dry thickness would be 20 μm, and the steel plate was baked at a maximum ultimate temperature of 215 ° C. for 45 seconds to form a resin layer.

Comparative Example 5 A coating type chrome on a hot-dip galvanized steel sheet having a thickness of 1.0 mm.
Pretreatment to achieve a chromium deposition of 50 mg / m ² by means of a heat treatment, and a total of 6 parts by weight of silicon polyester resin, polyethylene resin (molecular weight: 5,000) and PTFE resin (molecular weight: 2,000), respectively. The resin composition mixed with 12 parts by weight was rolled to a dry thickness of 25 μm.
Painted with a rucotor and 45 at the maximum steel plate reaching temperature of 215 ° C.
After baking for 2 seconds, a resin layer was provided.

Comparative Example 6 A hot-dip aluminum plated steel sheet having a thickness of 0.5 mm was pretreated by a coating chromate treatment so that the amount of chromium deposited was 50 mg / m ² , and a polyester resin (number average molecular weight:
Polyethylene resin (molecular weight: 5,000)
0) 1 part by weight of the mixed resin composition was coated with a roll coater to a dry thickness of 5 μm, and baked for 45 seconds at a steel plate maximum temperature of 215 ° C. to form a resin layer.

The resin layers of the base materials produced in Examples 6 to 10 and Comparative Examples 4 to 6 were overlapped with each other, and the applied pressure was 80 kg.
The layers were laminated by thermocompression bonding at a temperature of 180 ° C./cm ² for 2 hours, and the blocking resistance was investigated. Also, the base material is 1
The etching resistance was investigated by immersing in a 0% iron chloride solution.
The results are shown in Table 2. The evaluation was based on the following criteria. Symbol Blocking resistance Etching resistance ○: No blocking No pinhole △: Rough skin − ×; Blocking Yes Pinhole

[0030]

[Table 2]

[0031]

As described above, since the base material of the present invention has excellent adhesion and heat resistance to the resin insulating layer, the adhesion does not deteriorate even when heated in a solder bath. Also, since the resin film is provided on the side opposite to the conductive metal foil laminated side,
Workability is good because it is not necessary to attach a protective film when etching the conductive metal foil of the printed wiring board.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C08L 67/06 MSG (72) Inventor Kenji Koshiishi 7 Takatani Shinmachi, Ichikawa City, Chiba Pref. Steel Co., Ltd. Iron and Steel Research Institute Coat Research Department

Claims (2)

[Claims] 1. A metal plate base material for use in a printed wiring board, which comprises a base material surface on which a resin insulation layer and a conductive metal foil are sequentially laminated, and an epoxy resin or brominated on the base material resin insulation layer laminating side. A thermosetting resin layer having an epoxy resin as a skeleton and a phenol resin as a curing agent is baked and cured to obtain 10
A substrate for a printed wiring board, characterized in that the substrate is provided with a thickness of 50 μm. 2. A metal plate base material for use in a printed wiring board, comprising a resin insulation layer and a conductive metal foil laminated in this order on the surface of the base material, and a polyolefin on the side opposite to the resin insulation layer lamination side of the base material. At least one of resin and fluororesin is 2
To 30 parts by weight of a thermosetting polyester resin layer having a number average molecular weight of 10,000 or more by baking and curing to 5 to 30 parts.
A substrate for a printed wiring board, which is provided with a thickness of μm.