JP2002338823A - Heat-resistant film for substrate and printed wiring board obtained using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel heat-resistant film for a substrate improved in heat resistance, flame retardancy, dimensional stability an low environmental load properties which have been heretofore deemed as drawbacks of a thermoplastic resin composition when used as an insulting material for a printed wiring board, and a printed wiring board obtained using the same. SOLUTION: The heat-resistant film for a substrate is a film comprising 100 pts.wt. of a thermoplastic resin, and incorporated therewith, at least 20 but less than 50 pts.wt. of a scaly inorganic filler, where the scaly inorganic filler has the following characteristics: (1) The 90% average particle size measured by a laser diffraction grain size distribution method is less than 15 μm. (2) The aspect ratio (an average particle size/an average thickness) is at least 35. (3) A decrease in weight measured by the thermobalance method when the temperature is raised from room temperature to 400 deg.C is less than 0.5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant film for a substrate mainly used as an insulating material for a printed wiring board and a printed wiring board using the same.

[0002]

2. Description of the Related Art The miniaturization and multi-functionality of electronic equipment are accelerating year by year. The main technology supporting this is a semiconductor package and a printed wiring board on which electronic components are mounted. As a result, printed wiring boards are also required to have higher densities and accompanying higher performance, and the insulating materials of the wiring boards are required to have high heat resistance and flame resistance. In response to the increase in demand, it is also required to provide low environmental load (recyclability, no halogen element, use of lead-free solder). In addition, there is an extremely high demand for an insulating material that does not use glass cloth in order to cope with high density. This is because when a glass cloth is used, a resin / glass interface is continuously generated inside the substrate material, ion migration occurs, and the insulation resistance is reduced. For this reason, when using the current glass epoxy resin, the pitch between holes cannot be reduced to 350 μm or less, and it is impossible to cope with high density. According to the technology forecast of the printed circuit board in the near future, the printed circuit board used for the semiconductor package is L / S (conductor width / conductor spacing).
It is predicted that the pitch will be reduced to 15 μm / 15 μm or less, and it will be difficult to cope with the conventional method of forming a circuit by etching a copper foil by a subtractive method, and plating on a resin sheet or film will be difficult. It is expected that circuit formation by sputtering or sputtering will become mainstream.

[0003] In this case as well, in order to achieve a narrower L / S, the surface of the resin sheet or film is required to have a surface smoothness. Can not be used. Further, when the surface becomes smooth, it is necessary to improve the adhesion strength of plated copper or sputtered copper. Conventional insulating materials for printed wiring boards have been widely used for many years, formed by combining thermosetting resins such as epoxy resins and phenolic resins with reinforcing materials such as paper and glass fibers. These conventional substrates can no longer adequately meet the above requirements. Conventionally, polyimide has been used as a flexible substrate for a flexible substrate, but it still does not sufficiently meet demands in terms of recyclability and multilayering. On the other hand, conventionally, a high heat-resistant and flame-resistant thermoplastic resin, such as polyphenylene sulfide, polyethylene sulfide, polyetherimide, polyetheretherketone, etc., has an aspect ratio (average diameter /
The idea of using a composition filled with a scale-like inorganic filler such as mica having a large average thickness as an insulating material for a printed wiring board is disclosed in JP-A-61-41542 and JP-A-4-348095. As described in Japanese Unexamined Patent Publication No. Hei 4-356991, Japanese Unexamined Patent Publication No. Hei 4-348096, etc., the conventional technology does not solve the problems described below with respect to the above-described demand for high performance. However, it had not reached the level of practical use at all.

(A) Rigidity cannot be ensured in a temperature range (220 to 300 ° C.) of a component mounting process assumed up to lead-free soldering, and a board on which components are mounted is largely bent. (B) It is not possible to achieve the same linear expansion coefficient as the metal foil used to satisfy the dimensional stability as a substrate material, and the specifications of high-precision inorganic fillers are established (structure, dimensions, shape, characteristics, etc.) ) And high packing and uniform dispersion cannot be achieved. (C) If the amount of the inorganic filler is increased, the mechanical strength is significantly reduced, and does not reach the range of practical strength as a substrate material.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned problems in the case where a thermoplastic resin composition filled with a scaly inorganic filler is used as an insulating material for a printed wiring board. Another object of the present invention is to provide a novel heat-resistant film for a printed circuit board and a printed circuit board using the same as an insulating material for a printed circuit board having high heat resistance, flame resistance, dimensional stability and low environmental load.

[0006]

SUMMARY OF THE INVENTION The present invention has found a heat-resistant film for a substrate and a printed wiring board using the same, which can solve the above problems. The film is obtained by mixing the scaly inorganic filler in an amount of 20 parts by weight or more and less than 50 parts by weight per part, wherein the scaly inorganic filler has the following characteristics. (1) 90 measured by a laser diffraction particle size distribution method
(2) Aspect ratio (average particle size / average thickness) is 35 or more. (3) Weight loss measured by heating balance method from room temperature to 400 ° C. is 0.5% by weight. In the present invention, the scaly inorganic filler includes a heat-resistant film for a substrate, which is a fluorophlogopite synthesized by a melting method, and the thermoplastic resin has a crystal melting temperature of 260 ° C. The above polyaryl ketone resin 70-
25% by weight and amorphous polyetherimide resin 30 to 75
The printed wiring board is characterized by being composed of a mixture by weight, and further comprising a conductor layer formed on the heat-resistant film for a substrate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The scaly inorganic filler mixed with the thermoplastic resin applied to the heat-resistant film for a substrate and the printed wiring board using the same according to the present invention has a (1) 90% average particle diameter measured by a laser diffraction particle size distribution method. (2) Aspect ratio (average particle diameter / average thickness) of 35 or more, (3) Weight loss measured by heating balance method from room temperature to 400 ° C. is less than 0.5% by weight. Which has
It is necessary to mix the flaky inorganic filler in an amount of 20 parts by weight or more and less than 50 parts by weight with respect to 100 parts by weight of the thermoplastic resin. When the 90% average particle diameter of the above (1) is 15 μm or more, when the film is thinned to a thickness of 50 μm or less, for example, the smoothness of the film surface becomes extremely poor. L / S by
= 15 μm / 15 μm or less. Also,
An inorganic filler having a 90% average particle diameter of less than 15 μm and (2) an aspect ratio (average particle diameter / average thickness) of 35 or more,
The coefficient of linear expansion in the plane direction can be kept low, and the warpage of the substrate can be reduced.

When the amount of the above-mentioned inorganic filler exceeds 50 parts by weight with respect to 100 parts by weight of the resin composition, the end crack strength of the film is greatly reduced. The effect of reducing dimensional stability and improving dimensional stability is small, and in a reflow process or a flow process as a component mounting process, an internal stress due to a difference in linear expansion coefficient is generated, and warpage or torsion of the substrate occurs. For this reason, the preferable mixing amount of the inorganic filler is 100%.
It is 20 to 50 parts by weight based on parts by weight.

It is effective that the scaly inorganic filler used in the present invention does not have water of crystallization in the structure of the inorganic filler. (3) The temperature is raised from room temperature to 400 ° C. by a thermobalance method. Use a material having a weight loss of less than 0.5% when measured. This is because, when a thermoplastic resin having high heat resistance is formed into a film, the resin is melted at a high temperature of 300 ° C. to 450 ° C., and when the inorganic filler is dehydrated at this temperature,
This is because it induces deterioration of the resin and foaming of the film, and the mechanical strength of the film is greatly reduced. The most effective means for removing the water of crystallization of the inorganic filler having water of crystallization in its structure is to bake the inorganic filler before mixing with the thermoplastic resin.

As described above, the 90% average particle diameter is 15 μm.
m, an aspect ratio of 35 or more, and a scaly inorganic filler having no water of crystallization in its structure, a fluorophlogopite mica that is a kind of mica synthesized by a melting method (for example, manufactured by Topy Industries, Ltd. PDM-5B ") can be preferably used.
Natural phlogopite (eg, “W-40” manufactured by Repco Corp.) has a dehydration start temperature of crystallization water at 280 ° C., and fluorinated mica synthesized by a hydrothermal method (eg, Corp Chemical Co., Ltd.) Manufactured by "MK-200"), talc is used as a starting material, so that an aspect ratio of 30 or more cannot be obtained. Also, besides fluorophlogopite synthesized by the melting method,
Potassium tetrasilicic mica, potassium teniolite and the like may be appropriately selected according to the intended use and function of the resin composition.

The resin used in the present invention is not particularly limited as long as it has sufficient heat resistance and rigidity at the temperature at which components are mounted (220 ° C. to 300 ° C.), and various thermoplastic resin mixtures are used. I can do it. In the present invention, a resin composition comprising 70 to 25% by weight of a crystalline polyarylketone resin and 30 to 75% by weight of an amorphous polyetherimide resin can be suitably used. Here, the crystalline polyarylketone resin is a thermoplastic resin having an aromatic nucleus bond, an ether bond and a ketone bond in its structural unit, and typical examples thereof include polyetherketone, polyetheretherketone, and polyetherketone. There are ketones and the like. Polyetheretherketone is available from Victrex MC Corporation under the trade names “PEEK151G” and “PEEK3”.
81G "," PEEK450G "and the like.

Further, the amorphous polyetherimide resin is
It is an amorphous thermoplastic resin having an aromatic nucleus bond, an ether bond and an imide bond in its structural unit, and is not particularly limited. Polyetherimide is available from General Electric Co., Ltd. under the trade name “Ultem CRS5001”.
-1000 "," Ultem 1000-1000 "and the like. In the above resin composition, if the content of the crystalline polyarylketone resin exceeds 70% by weight or the content of the amorphous polyetherimide resin is less than 30% by weight, the crystallinity of the entire composition is high, and the crystallization rate is increased. In addition, beer strength tends to decrease during adhesion by heat fusion with a copper foil. When the content of the crystalline polyarylketone resin is less than 25% by weight or the content of the amorphous polyetherimide resin exceeds 75% by weight, the crystallinity itself of the composition as a whole is low, and the crystal melting temperature is 260 ° C or higher. Even so, the solder heat resistance is reduced. As described above, in the present invention, a mixed composition comprising 70 to 25% by weight of the polyarylketone resin and 30 to 75% by weight of the amorphous polyetherimide resin is suitably used.

The resin composition constituting the present invention contains various additives other than other resins and inorganic fillers, for example, heat stabilizers, ultraviolet absorbers, light stabilizers, nuclei, so long as the properties of the resin composition are not impaired. An agent, a coloring agent, a lubricant, a flame retardant, and the like may be appropriately blended. A known method can be used as a method for mixing various additives including the inorganic filler. For example,
(A) A high concentration of various additives in a suitable base resin such as a polyarylketone resin and / or an amorphous polyetherimide resin (a typical content is 10 to 60% by weight).
Separately) to prepare a master batch mixed with
(B) a method of mixing and adjusting the concentration to a resin to be used, and mechanically blending using a kneader or an extruder;
Examples include a method of mechanically blending various additives directly with the resin to be used using a kneader or an extruder. Among the above mixing methods, a method of preparing and mixing the master batch (a) is preferable from the viewpoint of dispersibility and workability.
Furthermore, the surface of the film may be appropriately subjected to embossing, corona treatment, or the like, for the purpose of improving handling properties and the like.

The heat-resistant film for a substrate of the present invention and the composition constituting a printed wiring board using the same are provided in the form of a film or sheet. As a forming method, a known method, for example, an extrusion casting method using a T-die, a calendar method, or the like can be adopted, and is not particularly limited, but from the viewpoints of film forming properties and stable productivity of the sheet. , T
Extrusion casting using a die 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.
30 ° C. or less. The thickness of the film is usually 2
5 to 200 μm.

Next, a method for producing a printed wiring board using the heat-resistant film for a substrate of the present invention can be adopted, and any known method described below can be adopted, and there is no particular limitation. 1) A method in which a conductive foil is thermally fused and crystallized on at least one surface of a film without an adhesive layer therebetween, and a conductive circuit is formed on the conductive foil by subtractive etching. Here, as a method of heat-sealing the film and the conductor foil without interposing an adhesive layer, a known method can be adopted as long as it can be heated and pressed, and is not particularly limited. For example, hot press method or hot laminating roll method,
Alternatively, a method in which these are combined can be suitably adopted. Examples of the conductive foil include a metal foil 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 as the conductor foil, it is preferable to use a material whose contact surface (overlapping surface) with the film is chemically or mechanically roughened in advance in order to enhance the bonding effect. . Specific examples of the conductor foil subjected to the surface roughening treatment include a roughened copper foil that has been electrochemically treated when producing an electrolytic copper foil.

2) A method in which a surface of a film is subjected to a surface roughening treatment by a mechanical or chemical method, and a conductive circuit is formed thereon by a plating method. The surface roughening treatment of the film is performed in order to increase the adhesion strength of the copper plating, and the chemical roughening method includes, for example, an oxidation treatment with a potassium permanganate solution.

3) A method of forming a conductive circuit by pattern-printing a conductive paste on the surface of a film by screen printing. 4) A method of providing a conductive circuit on the surface of a film by sputtering metal.

[0018]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In addition, various measurement values and evaluation tests in this specification were performed as follows.

(1) 90% average particle diameter Laser diffraction particle size distribution analyzer “LMS” manufactured by Seishin Enterprise Co., Ltd.
-30 "(wavelength: 680 nm) was used to determine the 90% average particle size of the flaky inorganic filler.

(2) Aspect ratio Laser diffraction particle size distribution analyzer “LMS” manufactured by Seishin Enterprise Co., Ltd.
The aspect ratio was obtained by dividing the 50% average particle diameter of the flaky inorganic filler obtained using “-30” by the average thickness of the flaky inorganic filler actually observed and obtained using an electron microscope.

(3) Weight loss at 400 ° C. The scale-like inorganic filler once sufficiently dried at 120 ° C. was heated from room temperature to 400 ° C. using a thermal balance “TAS-200” manufactured by Rigaku Corporation. The weight loss% was determined.

(4) Surface Smoothness of Film A cross-sectional curve was obtained by a two-dimensional surface roughness meter using a film having a thickness of 50 μm, and a reference length of 10 m was obtained from the cross-sectional curve.
m, and the ten-point average roughness (Rz) was determined from the difference between the average of the heights of the five highest projections and the average of the five lowest depressions in this reference length. . This R
When z was 5 μm or more, it was evaluated as (x), and when it was less than 5 μm, it was evaluated as (○).

(5) End Crack Strength of Film According to the end crack resistance test of JIS C2151, the thickness is 50%.
From a μm film to a 15 mm wide and 300 mm long sample
A test piece was cut out, and a tensile speed of 50
Measure the length and width in mm / min and measure
Is 39 N / mm ²The above is (○), 39 N / mm²Less than
(X).

(6) Peel strength of copper foil Copper foil (thickness: 18 μm, surface roughening) on one side of the film
To make a one-sided copper-clad board by hot pressing, JISC
The peel strength of the copper foil was determined according to 6481. A peel strength of 7.8 N / cm or more was evaluated as (○), a 5.9 N / cm or more was evaluated as (△), and a peel strength of less than 5.9 N / cm was evaluated as (x).

(7) Solder heat resistance Using a single-sided copper-clad board, according to JIS C6481,
Floating in a 0 ° C. solder bath for 20 seconds, and visually inspected for swelling or deformation. Those without swelling or deformation were rated as (○), those with slight deformation were rated as (△), and those with swelling or deformation were rated as (x).

(8) Warpage of substrate A single-sided copper-clad plate is prepared, cut into a square of 100 mm x 100 mm, and placed on a surface plate with the convex surface on the lower side to suppress one corner. The floating amount of the diagonal part was measured and defined as the amount of warpage of the substrate. (O) when the height of the warp was less than 2 mm, and (X) when the height was 2 mm or more.

(Example 1) As shown in Table 1, polyether ether ketone resin [Victrex MC Co., Ltd.
PEEK450G, Tg: 147.6 ° C., Tm: 3
34 ° C.] (hereinafter simply abbreviated as PEEK) 50 parts by weight, and a polyetherimide resin [Ultem-1000, manufactured by General Electric Co., Ltd., Tg: 216 ° C.]
(Hereinafter simply abbreviated as PEI) 50 parts by weight and fluorophlogopite mica “PDM-5B” (90% average particle diameter: 13.6 μm, aspect ratio: 50) synthesized by a melt synthesis method manufactured by Topy Industries, Ltd. ) At a set temperature of 380 ° C using an extruder equipped with a T-die.
After extruding into a film having a thickness of 75 μm, if necessary, a copper foil (thickness: 18 μm, surface roughening) is provided on one side thereof.
And heat pressed at 250 ° C. for 30 minutes to obtain a crystallized copper foil laminate. Using the obtained film or the single-sided copper-clad substrate, the evaluation results such as thermal characteristics and reliability tests are shown in Table 1.

(Example 2) As shown in Table 1, Example 1
In Example 1, except that the mixing weight ratio of PEEK and PEI was changed to 65/35 parts by weight, a target film or a single-sided copper-clad board was obtained in the same manner as in Example 1. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Example 3 As shown in Table 1, Example 1
In Example 1, except that the mixing weight ratio of PEEK and PEI was changed to 30/70 parts by weight, a target film or a single-sided copper-clad board was obtained in the same manner as in Example 1. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Example 4 As shown in Table 1, Example 1
The mixing weight ratio of PEEK and PEI was 70/30
A film or a single-sided copper clad board was obtained in the same manner as in Example 1 except that the amount was changed to parts by weight. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

(Embodiment 5) As shown in Table 1, Embodiment 1
The mixing weight ratio of PEEK and PEI is 25/75
A film or a single-sided copper clad board was obtained in the same manner as in Example 1 except that the amount was changed to parts by weight. Table 1 shows the evaluation results such as the thermal characteristics and reliability tests evaluated using the obtained film or single-sided copper-clad board.

Comparative Example 1 As shown in Table 1, Example 1
Of phlogopite "W" manufactured by Repco Co., Ltd.
Except for using "-40", a target film or a single-sided copper-clad board was obtained in the same manner as in Example 1. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Comparative Example 2 As shown in Table 1, Example 1
Of phlogopite "W" manufactured by Repco Co., Ltd. as an inorganic filler
90% by changing the classification conditions using “-40”
A target film or a single-sided copper-clad board was obtained in the same manner as in Example 1 except that the average particle size was adjusted to 13 μm. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Comparative Example 3 As shown in Table 1, Example 1
In the same manner as in Example 1 except that fluorphlogopite mica “MK-200” using a solid-phase reaction method manufactured by Corp Chemical Co., Ltd. was used as an inorganic filler, a target film or a single-sided copper-clad board was obtained. Was. Table 1 shows the evaluation results such as the thermal characteristics and reliability tests evaluated using the obtained film or single-sided copper clad board.

Comparative Example 4 As shown in Table 1, Example 1
Fluorophlogopite “PDM-5” in which the 90% average particle diameter was adjusted to 21 μm by changing the classification conditions of the inorganic filler in
A film or a single-sided copper-clad board was obtained in the same manner as in Example 1 except that "B" was used. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Comparative Example 5 As shown in Table 1, Example 1
A film or single-sided copper clad board was obtained in the same manner as in Example 1 except that the amount of the inorganic filler was changed to 15 parts by weight. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

Comparative Example 6 As shown in Table 1, Example 1
A film or a single-sided copper clad board was obtained in the same manner as in Example 1 except that the amount of the inorganic filler was changed to 55 parts by weight. Table 1 shows the evaluation results of the thermal characteristics, reliability tests, and the like evaluated using the obtained film or single-sided copper-clad board.

[0038]

[Table 1]

[0039]

According to the present invention, by optimizing a scaly filler to be added, a conventional thermoplastic resin composition filled with a scaly inorganic filler is used as an insulating material for a printed wiring board. The problem of high heat resistance,
To provide an insulating material for a printed wiring board, which has not only the flame resistance, the dimensional stability, and the low environmental load, but also the high density that the conventional insulating material for a printed circuit board could not reach, and a printed wiring board using the same. It became possible.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/03 610 H05K 1/03 610H 610R F term (Reference) 4F071 AA02 AA41 AA60 AA84 AB30 AD05 AD06 AD06 AE17 AF45 AF45Y AH13 BA01 BB06 BC01 4J002 AA01W CJ00W CM04X DJ056 FA006 FA016

Claims (4)

[Claims] 1. A film obtained by mixing a scaly inorganic filler in an amount of 20 parts by weight or more and less than 50 parts by weight with respect to 100 parts by weight of a thermoplastic resin, wherein the scaly inorganic filler has the following characteristics. Heat-resistant film for substrates. (1) 90 measured by a laser diffraction particle size distribution method
(2) Aspect ratio (average particle diameter / average thickness) is 35 or more. (3) Weight loss measured by heating balance method from room temperature to 400 ° C. is 0.5% by weight. Less than 2. A heat-resistant film for a substrate, wherein the scaly inorganic filler according to claim 1 is fluorophlogopite synthesized by a melting method. 3. The polyaryl ketone resin 70, wherein the thermoplastic resin according to claim 1 has a crystal melting temperature of 260 ° C. or higher.
-25% by weight and amorphous polyetherimide resin 30-7
A heat-resistant film for a substrate, comprising a 5% by weight mixture. 4. A printed wiring board, wherein a conductor layer is formed on the heat-resistant film for a board according to claim 1.