JP2001031818A - Heat-resistant insulating film and production of raw board for printed circuit board and substrate by using the same film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-resistant and insulating film excellent in resistance to soldering, flexibility, chemical resistance, mechanical strength and electrical characteristics, etc., and excellent in thermoformability at a low temperature and obtain a raw board for printed circuit board using the above film as a film-like insulating material. SOLUTION: This heat-resistant and insulating film comprises a film-like insulator consisting essentially of a styrene-based resin composition having syndiotactic structure and a thermoplastic resin having compatibility with the styrene-based resin composition and having >=35 wt.% of the above styrene-based resin composition and having >=260 deg.C crystal melting peak temperature measured when temperature is raised by differential scanning calorimetry. This raw board for printed circuit boards is obtained by optionally providing a through hole in the above heat-resistant and insulating film and packing an electroconductive paste into the hole and thermally fusing a conductive foil to at least one face of the film. In the raw board, crystal melting calorie ΔHm and crystallization calorie ΔHc generated by crystallization during heat-up, measured when heated up by differential scanning calorimetry after heat fusion satisfy the following relationship: [(ΔHm-ΔHc)/ΔHm]<=0.6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant insulating film, a substrate for a printed wiring board using the same, and a method for manufacturing a printed wiring board. More specifically, a thermoplastic resin film having excellent solder heat resistance, flexibility, chemical resistance, mechanical strength, electrical properties, and the like, and having excellent thermoforming properties (heat fusing properties) at low temperatures and this film. The present invention relates to a method for manufacturing a base plate and a substrate using the same as an insulating material for a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, the most common printed wiring board is a prepreg (hereinafter referred to as a glass epoxy resin) obtained by impregnating a glass cloth (nonwoven fabric of glass fiber) with a thermosetting epoxy resin as an insulating material. The pressure is usually 10 to 40 kgf / cm ² , and the temperature is 170.
A substrate is used in which a conductor foil such as a copper foil is bonded by hot press molding under the conditions of about 230 ° C. and a time of about 30 to 120 minutes.

[0003] Glass epoxy resin is excellent in solder heat resistance and chemical resistance, and is relatively inexpensive. However, since it contains glass fiber, cracks occur when a shock such as dropping is applied, resulting in poor conduction. There is a problem in that it takes a long time to cure the epoxy resin at the time of hot press molding, and the productivity is poor.

In recent years, in response to the reduction in size and weight of electronic devices such as notebook personal computers and mobile phones, there has been a demand for higher density wiring and smaller and lighter circuit boards. Investigations on multilayer substrates using a thermoplastic resin film as an insulating layer are being actively conducted.

[0005] When a thermoplastic resin film is used as an insulating material for a printed wiring board, various advantages can be expected.
Compared with the conventional glass epoxy resin, the circuit board can be reduced in size and weight, the impact resistance can be improved, the molding time during hot press molding can be reduced, and the productivity is also advantageous. Originally, the insulation material for printed wiring boards requires solder heat resistance in the manufacturing process, but if a heat-resistant thermoplastic resin can be used, the electrical characteristics at high temperatures will be excellent, and the circuit under high temperature atmosphere will be excellent. We can expect to get the reliability of

However, these heat-resistant thermoplastic resins have a high molding temperature, so that an adhesive such as an epoxy resin or the like may be used for bonding conductors or forming a multilayer substrate.
It is necessary to perform hot press molding at a high temperature of 60 ° C or more,
Considering that it takes time to raise and lower the temperature, the advantage of the thermoplastic resin in productivity is impaired.
Furthermore, in the case of a crystalline resin, there is a problem that the adhesiveness cannot be obtained unless the resin is heated to a temperature close to the melting point, and when the temperature exceeds the melting point, the resin starts to flow out and undergoes flow deformation.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide excellent solder heat resistance, flexibility, chemical resistance, mechanical strength, electrical properties, etc., and low-temperature thermoformability (heat-fusibility). An object of the present invention is to provide a heat-resistant insulating film excellent in (1) and a substrate for a printed wiring board using the same as a film-like insulating material, and to provide an industrially advantageous method for manufacturing a substrate.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a styrene resin composition having a syndiotactic structure and a thermoplastic resin compatible with the styrene resin are the main components. By using a heat-resistant insulating film to be, further, by controlling the thermal characteristics of the film when assembling and processing the printed wiring board to a specific range,
The present inventors have found a raw plate for a printed wiring board and a method for manufacturing a substrate using the same, which can solve the above problems, and have completed the present invention.

That is, the gist of the present invention is as follows.
A styrene-based resin composition having a syndiotactic structure, and a film-like insulator mainly containing a thermoplastic resin compatible with the styrene-based resin and having a styrene-based resin composition content of 35% by weight or more. The crystal melting peak temperature measured when the temperature is increased by differential scanning calorimetry is 26.
0 ° C. or higher, and the heat-resistant insulating film is characterized in that the heat of crystal fusion ΔHm and the heat of crystallization ΔHc generated by crystallization during temperature increase satisfy the following relational expression.

[(△ Hm- △ Hc) / △ Hm] ≦ 0.4 Further, another gist of the present invention is to provide a conductive paste by providing a through-hole in the heat-resistant insulating film if necessary. After filling, at least one surface thereof is a base plate for a printed wiring board obtained by heat-sealing a conductive foil, and after the heat-sealing, the crystal melting is measured when the temperature is raised by differential scanning calorimetry. The amount of heat ΔHm and the amount of heat of crystallization ΔHc generated by crystallization during temperature rise satisfy the following relational expression: [(ΔHm−ΔHc) / ΔHm] ≦ 0.6. Exist.

[0011] Further, another gist of the present invention is that the above-mentioned printed wiring board base plate is subjected to an etching process required for forming a circuit on its conductive foil, and then fused through a heat-resistant insulating film, In the method of manufacturing a printed wiring board having a multilayer structure, after the heat fusion, the heat of crystal fusion ΔHm and the heat of crystallization ΔHc satisfy the following relational expression [(ΔHm−ΔHc) / ΔHm] ≧ 0.7 A method for manufacturing a printed wiring board is characterized in that:

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. In the present invention, the styrene-based resin having a syndiotactic structure as the first component constituting the heat-resistant insulating film has a stereochemical structure having a syndiotactic structure,
That is, it has a three-dimensional structure in which phenyl groups and substituted phenyl groups, which are side chains, are alternately located in opposite directions to the main chain formed from CC bonds.

The content of the styrene resin is preferably 35% by weight or more and 35 to 70% by weight of the heat-resistant insulating film. If the content is less than 35% by weight, the solder heat resistance is poor.
If it exceeds 70% by weight, the adhesion to the conductor foil tends to be poor.

Further, a second heat-insulating film may be used.
As the thermoplastic resin having compatibility with the styrene-based resin as the component, any resin capable of being uniformly dispersed at the time of melt molding may be used, and polyolefin-based, polystyrene-based, polyester-based, polyamide-based, polyphenylene ether-based, Examples include polyphenylene sulfide-based resins, but are not limited thereto. In the present invention, a modified polyphenylene ether (modified PPE) is preferably used. The content of the thermoplastic resin compatible with the styrene resin is preferably in the range of 30 to 65% by weight of the heat-resistant insulating film, and if it is less than 30% by weight, the adhesiveness to the conductor foil tends to be poor. If it exceeds 65% by weight, the solder heat resistance tends to be poor.

The heat-resistant insulating film may further contain a rubber-like elastic material for the purpose of improving mechanical strength in addition to the above-mentioned components. As the rubber-like elastic material, a styrene-butadiene block copolymer ( SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS),
Examples include, but are not limited to, hydrogenated styrene-butadiene-styrene block copolymer (SEBS). In the present invention, SEBS is preferably used among the rubbery elastic bodies. The rubber-like elastic body is preferably contained in the range of 10 to 20% by weight of the heat-resistant insulating film, and if it is less than 10% by weight, the effect of improving the strength is small, and if it exceeds 20% by weight, the heat resistance tends to decrease. is there.

Further, in the present invention, the heat-resistant insulating film needs to have specific physical properties. That is, a film having the above composition, wherein the crystal melting peak temperature measured when the temperature is raised by differential scanning calorimetry is 2
It is 60 ° C. or higher, and the heat of crystal fusion ΔHm and the heat of crystallization ΔHc generated by crystallization during temperature rise must satisfy the following relational expression.

[(△ Hm- △ Hc) / △ Hm] ≦ 0.4 When the crystal melting peak temperature of the above film is less than 260 ° C., there is a problem that the solder heat resistance is reduced.

The thermal characteristic, which is the most important control factor in the present invention, is represented by the following relational expression between the heat of crystal fusion ΔHm of the film and the heat of crystallization ΔHc generated by crystallization during temperature rise.

[(ΔHm−ΔHc) / ΔHm] That is, the thermal characteristics are defined by JIS K7121 and JIS K7121.
In differential scanning calorimetry according to K7122, measured values of two heats of transition appearing in the DSC curve when the temperature is raised, heat of crystal fusion ΔHm (J / g) and heat of crystallization ΔHc (J / g)
Is calculated according to the above equation from the value of.

This relational expression [(ΔHm−ΔHc) / ΔH
The value of m] also depends on the type and molecular weight of the raw material polymer, the ratio of the composition, and the like, but greatly depends on the molding and processing conditions of the heat-resistant insulating film. That is, when the film is formed into a film, the raw material polymer is melted and then cooled immediately, whereby the numerical value can be controlled to be small.
Further, these numerical values can be controlled by adjusting the heat history in each step. The thermal history refers to the temperature of the film and the time during which the temperature has been reached, and the numerical value tends to increase as the temperature increases or as the time increases.

In the heat-resistant insulating film, if this value exceeds 0.4, the degree of crystallinity before bonding with the conductor foil by heat fusion is already high, and It is necessary to perform the bonding at a high temperature, or crystallization proceeds excessively during bonding with the conductor foil by thermal fusion, making it difficult to form a multilayer substrate by thermal fusion.

Next, the most important aspect of the control of the relational expression is that in the process of manufacturing the printed wiring board,
First, the value based on the measurement after the heat fusion of the base plate for a printed wiring board obtained by thermally fusing a conductive foil to at least one surface of a heat-resistant insulating film is to satisfy the following relational expression.

[(ΔHm−ΔHc) / ΔHm] ≦ 0.6 If this value exceeds 0.6, the adhesiveness due to thermal fusion in the multilayering process of the substrate is reduced, and multilayering becomes difficult. Similarly, for the heat-resistant insulating film before the heat-sealing with the conductor foil, the value of the above relational expression is preferably as small as possible. For example, if it exceeds 0.6 before heat fusion, the crystallinity before bonding by heat fusion with the conductor foil is already high, and the bonding molding temperature by heat fusion with the conductor foil is performed at a high temperature. It is necessary or crystallization proceeds excessively during bonding by thermal fusion with the conductor foil, making it difficult to form a multilayer substrate by thermal fusion.

Finally, in order to realize the solder heat resistance after the multilayering, the printed wiring board base plate is fused with a heat-resistant insulating film through a heat-resistant insulating film to obtain a multilayer printed wiring board. The value based on the measurement after the heat fusion satisfies the following relational expression.

[(ΔHm−ΔHc) / ΔHm] ≧ 0.7 If this value is less than 0.7, crystallization is insufficient.
It is not preferable because solder heat resistance is reduced.

In the present invention, the resin composition constituting the heat-resistant insulating film is added to such an extent that its properties are not impaired.
Other resins and additives, such as heat stabilizers, UV absorbers,
Various additives such as a light stabilizer, a nucleating agent, a coloring agent, a lubricant, a flame retardant, and a filler such as an inorganic filler may be appropriately compounded. Further, the surface of the heat-resistant insulating film may be appropriately subjected to embossing, corona treatment, or the like in order to improve handling properties.

As a method of forming a heat-resistant insulating film,
A known method, for example, an extrusion casting method using a T-die, a calendar method, or the like can be employed, and is not particularly limited. However, from the viewpoint of film forming properties and stable productivity, a T-die is used. Extrusion casting is preferred. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics, film forming properties, and the like of the composition, but is generally from the melting point to 310 ° C. In addition, the thickness of the film,
Usually, it is 25 to 300 μm.

The printed wiring board of the present invention uses a heat-resistant insulating film, and can be manufactured in a number of layers according to the purpose. First, a predetermined through hole is provided in the heat-resistant insulating film. After the conductive paste is filled, a conductor foil, for example, a copper foil, is heat-sealed on both surfaces to form a printed wiring board blank (also referred to as a “double-sided copper-clad board”). A four-layer substrate can be manufactured by forming a conductive pattern, using two obtained materials, providing a predetermined through hole in the middle, and interposing a heat-resistant insulating film filled with a conductive paste. The conductive patterns are connected to each other by a conductive paste. Similarly, it is also possible to create a substrate having six or more layers.

Examples of the conductor foil used in the present invention include metal foils having a thickness of about 5 to 70 μm, such as copper, gold, silver, aluminum, nickel and tin. As the metal foil, a copper foil is usually used, and a metal foil whose surface has been subjected to a chemical conversion treatment such as a black oxidation treatment is preferably used.

In the method of manufacturing a printed wiring board, a known method can be adopted as a method of heat fusion as long as it can be heated and pressed, and is not particularly limited. A method, a heat laminating roll method, or a method combining these methods can be suitably employed.

[0031]

The present invention will be described in more detail with reference to the following examples.
The present invention is not limited by these.
Various measurements and evaluations of the film displayed in the present specification were performed as follows.

(1) Glass transition temperature, crystallization temperature, crystal melting peak temperature Sample 1 was prepared using DSC-7 manufactured by Perkin Elmer Co., Ltd.
0 mg according to JIS K7121 at a heating rate of 10
It was determined from the thermogram when the temperature was raised at ° C / min.

(2) (ΔHm−ΔHc) / ΔHm Sample 1 was obtained by using DSC-7 manufactured by PerkinElmer Co., Ltd.
0 mg according to JIS K7122, heating rate is 10
The heat of crystal fusion ΔHm (J / g) and the heat of crystallization ΔHc (J / g) were calculated from the thermogram when the temperature was raised at a rate of ° C./min.

(3) Adhesive strength Copper foils on both sides were measured in accordance with the normal peel strength of JIS C6481, and the average value was measured in kgf.
/ Cm.

(4) Solder heat resistance According to the normal solder heat resistance of JIS C6481, 2
The test piece was floated in a solder bath at 60 ° C. for 10 seconds so that the copper foil side and the solder bath were in contact with each other, cooled to room temperature, and visually inspected for swelling or peeling to determine the quality.

(5) Folding Resistance A double-sided copper-clad board was prepared and subjected to a 180 ° bending resistance test to determine the number of times the film was cracked when a crack was formed.

Example 1 A styrenic resin group having a syndiotactic structure [Zarek, manufactured by Idemitsu Petrochemical Co., Ltd.] (hereinafter sometimes abbreviated simply as SPS) 60% by weight and modified PPE [Mitsubishi Engineering Plastics Co., Ltd., Iupiece] 40% by weight was extruded using a 40 mmφ twin screw kneading extruder (L / D = 35) manufactured by Mitsubishi Heavy Industries, Ltd. equipped with a T die, and the temperature was adjusted. The film was immediately brought into contact with a cast roll having a function and solidified to obtain a film having a thickness of 100 μm. Extrusion conditions were as follows.

Extrusion set temperature 290 to 310 ° C. Extruded amount 20 kg / h Cast roll temperature 95 ° C. (Example 2) In Example 1, the proportion of the mixed composition was set to S
A film was obtained in the same manner except that PS was changed to 40% by weight and modified PPE was changed to 60% by weight.

(Reference Examples 1 to 3) In Example 1, the proportions of the mixed compositions were respectively 100% by weight of SPS (Reference Example 1), 30% by weight of SPS, and 70% by weight of modified PPS.
A film was obtained in the same manner as in (Reference Example 2) except that the modified PPE was changed to 100% by weight (Reference Example 3). Next, with respect to the films obtained in the above Examples and Reference Examples, the glass transition temperature, the crystallization temperature, the heat of crystallization ΔHc, the crystal melting peak temperature, and the heat of crystal fusion ΔHm were measured, and (ΔHm−ΔHc) / ΔHm was calculated. The results are summarized in Table 1.

[0040]

[Table 1]

Example 3 The film obtained in Example 1 was cut into A4 size, electrolytic copper foil having a thickness of 18 μm was laminated on both sides, and the pressure was 30 kgf / cm ² , the temperature was 160 ° C.
Bonding was performed by a hot press under the conditions of a time of 10 minutes to produce a double-sided copper-clad plate. Further, after a circuit is formed by etching, a new film is laminated between the two sets of double-sided copper-clad boards on which the circuit is formed, and a pressure of 30 kgf / c is applied.
Under a condition of m ² , a temperature of 180 ° C., and a time of 20 minutes, a multilayer was formed by hot pressing to produce a four-layer substrate. The peeling of the copper foil during the processing step has no problem, and the obtained four-layer substrate
The adhesion between the layers and the adhesive strength with the copper foil were sufficient, and the solder heat resistance was also good.

(Comparative Example 1) A four-layer substrate was produced in the same manner as in Example 3, except that the hot pressing temperature for producing the double-sided copper-clad board was changed to 180 ° C. The obtained four-layer substrate had insufficient adhesion between the layers and was easily peeled.

(Embodiment 4) In Embodiment 3, Embodiment 1
To the film obtained in Example 2,
In addition, the hot press temperature for producing a double-sided copper-clad board is 17
At 0 ° C, the hot pressing conditions for producing a four-layer substrate were set at a temperature of 1
A four-layer substrate was prepared in the same manner except that the temperature was changed to 90 ° C. and the time was 30 minutes. There was no problem in peeling of the copper foil during the processing step, and the obtained four-layer substrate had sufficient adhesion between the layers and adhesive strength with the copper foil, and also had good soldering heat resistance.

(Comparative Example 2) In Example 4, the hot pressing conditions for producing a four-layer substrate were set to 170 ° C. for 10 hours.
A four-layer substrate was produced in the same manner except that the number of minutes was changed.
The resulting four-layer substrate had good adhesion between layers, but poor soldering heat resistance.

(Comparative Example 3)
To the film obtained in Reference Example 2,
In addition, a hot press temperature of 220 when producing a double-sided copper-clad board is used.
A double-sided copper-clad board was produced in the same manner except that the temperature was changed to 20 ° C. for 20 minutes. Evaluation results for the double-sided copper-clad board and the four-layer board obtained in these Examples and Comparative Examples
The results are summarized in Table 2.

[0046]

[Table 2]

Referring to Examples 1 to 4 in Tables 1 and 2, when the raw material composition of the film is within the specified range and has a specific thermal characteristic, the conductor foil at a low temperature (250 ° C. or lower) is used. When a multilayer substrate is produced, the value of (ΔHm−ΔHc) / ΔHm is reduced to 0.6 or less after the bonding step by heat fusion with a conductive foil. After the process, the temperature is controlled to 0.7 or more, and if each is controlled, the low temperature (2
It can be seen that multi-layering at 50 ° C. or lower is possible and the soldering heat resistance is good. On the other hand, as in Comparative Examples 1 and 2, (ΔHm−ΔHc) / ΔH
When the value of m is not controlled within the specified range, it can be seen that multilayering becomes difficult and solder heat resistance becomes poor. Further, as in Comparative Example 3, when the raw material composition of the film is out of the specified range, it can be seen that the adhesive strength with the copper foil of the obtained double-sided copper-clad board is low and it is difficult to form a multilayer.

[0048]

According to the present invention, the heat resistance, the flexibility, the chemical resistance, the mechanical strength, the electrical properties, etc., are excellent, and the thermoformability (heat fusion property) at a low temperature is excellent. A heat-resistant insulating film and a method for manufacturing a substrate for a printed wiring board and a method for manufacturing a substrate using the same as a film-like insulating material can be provided.

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Claims (7)

[Claims] 1. A styrenic resin composition having a syndiotactic structure, and a thermoplastic resin compatible with the styrenic resin composition as a main component, and the content of the styrenic resin composition is 35% by weight or more. Having a crystal melting peak temperature of 260 ° C. or higher measured when the temperature is increased by differential scanning calorimetry;
Hm and the heat of crystallization generated by the crystallization during the heating △ Hc
Satisfies the following relational expression: [(△ Hm- △ Hc) / △ Hm] ≦ 0.4 2. A styrenic resin composition having a syndiotactic structure and a thermoplastic resin compatible with the styrenic resin composition as a main component, and the content of the styrenic resin composition is 35% by weight or more. The film-like insulator of the above, the crystal melting peak temperature measured when the temperature is raised by differential scanning calorimetry is 260 ℃ or more heat-resistant insulating film, if necessary, through holes provided conductive paste After filling, at least one surface thereof is a base plate for a printed wiring board obtained by heat-sealing a conductive foil, and after the heat-sealing, the crystal melting is measured when the temperature is raised by differential scanning calorimetry. A substrate for a printed circuit board, wherein the heat quantity ΔHm and the heat quantity of crystallization ΔHc generated by crystallization during temperature rise satisfy the following relational expression: [(ΔHm−ΔHc) / ΔHm] ≦ 0.6. 3. A styrene resin composition having a syndiotactic structure and a thermoplastic resin compatible with the styrene resin composition as a main component, and the content of the styrene resin composition is 35% by weight or more. The film-like insulator of the above, the crystal melting peak temperature measured when the temperature is raised by differential scanning calorimetry is 260 ℃ or more heat-resistant insulating film, if necessary, through holes provided conductive paste After filling, at least one surface thereof is a method for producing a printed wiring board base plate by heat-sealing a conductive foil, which is measured when the temperature is raised by differential scanning calorimetry after the heat-sealing. And a heat of crystallization ΔHm and a heat of crystallization ΔHc generated by crystallization during temperature increase satisfy the following relational expression: [(ΔHm−ΔHc) / ΔHm] ≦ 0.6 Elementary Plate manufacturing method. 4. The method according to claim 3, wherein the heat-sealing of the heat-resistant insulating film and the conductive foil is performed at a temperature equal to or higher than a glass transition temperature of the heat-resistant insulating film. A method for producing a bare plate for a printed wiring board, which is performed at a temperature of less than. 5. The printed wiring board base plate obtained by the manufacturing method according to claim 3 is subjected to an etching treatment required for forming a circuit on a conductive foil thereof, and then through a heat-resistant insulating film. In the method for manufacturing a printed wiring board that is heat-sealed and multilayered, the heat of crystal fusion ΔHm and the heat of crystallization ΔHc satisfy the following relational expression after the heat fusion: [(ΔHm−ΔHc) / ΔHm] ≧ 0.7. A method for manufacturing a printed wiring board. 6. The method for manufacturing a printed wiring board according to claim 5, wherein the heat-sealing of the heat-resistant insulating film and the conductive foil and the heat-sealing at the time of multilayering are performed at a temperature of 190 ° C. or less. A method for manufacturing a printed wiring board, characterized in that: 7. The heat-resistant insulating film according to claim 1, comprising a rubber-like elastic body in a range of 10 to 20% by weight.