JPH05327148A - Laminated plate for printed circuit - Google Patents

Abstract

PURPOSE:To provide a laminated plate for printed circuit with the small thermal expansion coefficient and excellent through hole reliability. CONSTITUTION:Within this laminated plate for printed circuit comprising an insulating layer and a conductive layer, the insulating layer is composed of a prepreg impregnated with a thermosetting resin and dried up to be molded and set on a base material containing more then 50% of para-base aromatic polyamide fiber. At this time, the thermal expansion coefficient of this insulating layer within the range of 25-125 deg.C is to be specified as 9-11ppm/K in facial direction and 80-120ppm/K in thickness direction. Through these procedures, the title lamimated plate in the small thermal coefficient, causing no solder cracking at all and having enhanced through hole reliability can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board for a printed circuit, which is suitable for mounting a semiconductor device having a package having a small coefficient of thermal expansion such as CLCC or TSOP and which has excellent through hole reliability.

[0002]

2. Description of the Related Art Recent technological innovations have been remarkable, and downsizing of electronic devices has never stopped. This is due to high-density packaging technology, high integration of semiconductors, and miniaturization technology of semiconductor packages.
(Ceramic leadless chip carrier), TSOP (thin
Small outline package) and other semiconductor devices with a smaller package size than the semiconductor chip size are becoming popular. However, a typical copper clad laminate that has been conventionally used as a printed circuit board for industrial equipment,
That is, a copper clad laminate formed by integrally molding a prepreg and a copper foil, which are impregnated with a thermosetting resin and dried on a base material such as glass cloth, under heat and pressure, is not necessarily required for mounting semiconductor devices such as CLCC and TSOP. Not a good fit.

The package material of CLCC is ceramics, and the coefficient of thermal expansion is greatly different from that of a glass-based epoxy laminate generally used, and it has no lead for absorbing thermal stress. Even if the package material of the TSOP is an epoxy resin encapsulant, the amount of the resin encapsulant for the silicon chip is small, and the overall coefficient of thermal expansion is much smaller than that of the conventional package, and the leads are also very short. Therefore, when both are mounted on a glass-based epoxy laminate, there is a drawback that solder crack defects frequently occur due to mismatch of thermal expansion coefficients. Therefore, an aramid-based epoxy laminate may be used as the laminate having a small coefficient of thermal expansion in the plane direction. However, the aramid cloth laminate is very difficult to machine, expensive and not suitable for practical use. In addition, the thermal expansion coefficient of the aramid paper laminated plate is kept very low at 6 to 8 ppm / K, while the thermal expansion coefficient of the thickness direction is very large at 130 to 300 ppm / K, which makes it possible to improve the through hole reliability of the substrate. There was a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a small coefficient of thermal expansion, does not cause solder cracks, and has excellent through-hole reliability.
It is intended to provide a laminated board for a printed circuit, which is most suitable for mounting a semiconductor device such as C or TSOP.

[0005]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that the use of a base material containing 50% or more of para aromatic polyamide fiber results in The present invention has been completed by finding out that the above object can be achieved.

That is, the present invention is a laminated board for a printed circuit comprising an insulating layer and a conductive layer, wherein the insulating layer impregnates a base material containing 50% or more of para aromatic polyamide fiber with a thermosetting resin.・ A layer obtained by molding and curing a dried prepreg. The thermal expansion coefficient of the insulating layer in the temperature range of 25 to 125 ℃ is 9 to 11 ppm / K in the plane direction and 80 to 120 p in the thickness direction.
It is a laminated board for a printed circuit characterized by having pm / K.

The present invention will be described in detail below.

The substrate used in the present invention includes cloth, paper, non-woven fabric and the like containing 50% or more of para-aromatic polyamide fiber, and these can be used alone or in combination. Fibers other than the para-aromatic polyamide fiber can be used in combination with glass cloth, cellulose, fibers made of synthetic resin, woven cloth made of metal fibers, nonwoven cloth, paper and the like. If the ratio of para-aromatic polyamide fiber in the base material is less than 50%, 25 to 12
Coefficient of thermal expansion in the plane direction of 9 to 11 ppm in the temperature range of 5 ° C
/ K and 80 to 120 ppm / k in the thickness direction cannot be maintained, which is not preferable.

The thermosetting resin used in the present invention is a thermosetting resin whose viscosity is adjusted so that the base material can be easily impregnated with a solvent. As a concrete resin, epoxy resin,
Polyimide resins and modified resins thereof are preferably used, but not limited thereto. A solvent is added to the thermosetting resin to form a varnish, and the varnish can be blended with a filler having a high thermal conductivity or a low dielectric constant as long as the purpose of the present invention is not impaired. Examples of the filler having good thermal conductivity include aluminum hydroxide and silica, and examples of the filler having a low dielectric constant include fluororesin powder and hollow glass beads. If necessary, talc, calcium carbonate and the like can be appropriately added. The varnish thus obtained is impregnated into the above-mentioned base material and dried to form a prepreg, and the prepreg can be used as an insulating layer to produce a laminated board for a printed circuit.

The conductive layer constituting the laminate for a printed circuit of the present invention is not particularly limited as long as it can form a circuit with a metal foil, a metal plating layer, a conductive paste layer and the like.
Especially when a metal foil such as a copper foil is used, a plurality of the above-mentioned prepregs are stacked, the metal foil is arranged on at least one surface of the prepreg, sandwiched between stainless steel plates and laminated integrally by a heat press, and conductive by selective etching. Since the layers can be formed, they are suitable for mass production and have manufacturing advantages. When a metal plating layer is used, a laminated plate with an adhesive is prepared, and only a necessary portion is plated on the surface of the adhesive to form a conductive layer. When the circuit is formed by the conductive paste layer, the conductive layer can be formed on the surface of the laminated plate by screen printing or the like.

The printed circuit laminate thus manufactured can be suitably used as a circuit board for mounting a semiconductor device such as CLCC or TSOP having a small coefficient of thermal expansion in the plane direction.

[0012]

The para-aromatic polyamide fiber has a negative coefficient of thermal expansion in the spinning direction, but the coefficient of thermal expansion in the radial direction of the fiber is positive. Therefore, when the fiber orientation is biased in the plane direction during papermaking, the coefficient of thermal expansion in the plane direction is negative, and the substrate has a large coefficient of thermal expansion in the thickness direction. A laminated plate obtained by impregnating a base material of this type with a resin has a small coefficient of thermal expansion in the plane direction, but a large coefficient of thermal expansion in the thickness direction. This is in addition to the behavior of the substrate,
This is a result of the expansion stress of the matrix resin of the laminated plate in which the thermal expansion in the surface direction is suppressed, concentrated in the thickness direction. There are various methods for suppressing the thermal expansion coefficient of the para-aromatic polyamide fiber base material in the thickness direction, but there is no particular limitation, and any method can be used, or a combination method may be used. By adjusting the balance between the thermal expansion coefficient of the substrate in the plane direction and the thermal expansion coefficient of the thickness direction, the balance of the expansion coefficient of the laminated plate could be adjusted. The printed circuit laminate of the present invention has a coefficient of thermal expansion in the plane direction of 9 to 11 ppm / k and a thickness direction of 80 to 120 ppm / K in the temperature range of 25 to 125 ° C.
By adjusting the above, it was possible to match the coefficient of thermal expansion in the plane direction with a semiconductor device such as CLCC or TSOP and to improve the reliability of the through hole.

[0013]

EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example A prepreg was prepared by impregnating and drying a heat-resistant epoxy resin varnish on a Cermount (trade name, manufactured by DuPont), a para-aromatic polyamide paper substrate having a random fiber orientation of 0.07 mm, and using this prepreg. 11 sheets are stacked, electrolytic copper foil with a thickness of 18 μm is placed on both sides, sandwiched between stainless steel plates, and laminated by heat press to form a laminated body with a thickness of 0.8 mm.
Of the printed circuit board was manufactured.

Comparative Example 1 A prepreg was prepared by impregnating and drying a heat-resistant epoxy resin varnish, Technora (manufactured by Teijin Ltd., trade name), a para-aromatic polyamide paper substrate having a fiber plane orientation of 0.1 mm. 8 sheets are piled up and 18 μm thick on both sides
The electrolytic copper foil of 1 was placed, sandwiched between stainless steel plates, and integrally laminated by hot pressing to produce a 0.8 mm-thick printed circuit laminate.

Comparative Example 2 A laminated board (FR-4 grade) for a general-purpose glass substrate epoxy printed circuit having a thickness of 0.8 mm was prepared.

The printed circuit laminates manufactured in Examples and Comparative Examples 1 and 2 were tested for thermal expansion coefficient, TSOP connection stability, and through hole reliability. The results are shown in Table 1. The present invention is excellent in all properties, and the effect of the present invention was confirmed.

[0018]

[Table 1] * 1: Thermal expansion coefficient measurement temperature range CTEα ₁ 25 to 125 ℃
.. * 2: Test condition Air heat cycle -40 ℃ ・ 1h〜15
0 ℃ ・ 1h.

[0019]

As is apparent from the above description and Table 1, the printed circuit laminate of the present invention has a small coefficient of thermal expansion, is free from solder cracks, and has excellent through-hole reliability. , TSOP, etc. are most suitable for mounting semiconductor devices.

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B32B 15/08 J

Claims (1)

[Claims] 1. A laminated board for a printed circuit, comprising an insulating layer and a conductive layer, wherein the insulating layer is a prepreg obtained by impregnating a base material containing 50% or more of para aromatic polyamide fiber with a thermosetting resin and drying. Is a layer which is molded and cured, and the thermal expansion coefficient of the insulating layer in the temperature range of 25 to 125 ° C. is 9 to 11 ppm / K in the plane direction and 80 to 120 ppm / K in the thickness direction. Characteristic printed circuit board.