JPH0590720A - Composite printed wiring board - Google Patents

Abstract

PURPOSE:To furnish a composite printed wiring board enabling improvement of the reliability in connection with an electronic component and prevention of a damage on the electronic component, by making the thermal expansion coefficient of the whole of the board approximate to the thermal expansion coefficient of a semiconductor integrated circuit TSO or a bare chip IC. CONSTITUTION:In a printed wiring board having a composite insulating material layer 13 prepared by impregnating pore spaces of porous ceramic or porous glass solvent-welded on the rear of a copper leaf 12, with thermosetting resin, a base plate 11 prepared by impregnating the pore spaces of porous ceramic with the thermosetting resin and the composite insulating material layer 13 are laminated by a prepreg 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite printed wiring board in which a ceramic or glassy material and a thermosetting resin are composited, and in particular, porous ceramics or porous glassy holes welded to the back surface of a copper foil. The present invention relates to a printed wiring board having a composite insulating material layer in which a gap is impregnated with a thermosetting resin.

[0002]

2. Description of the Related Art Conventionally, wiring board materials are roughly classified into organic materials such as glass epoxy and inorganic materials such as alumina. Ceramic wiring boards using inorganic materials are building a unique field by taking advantage of their high heat resistance, high heat dissipation and low thermal expansion. However, the ceramic wiring board is inferior in mass productivity due to the complicated processing steps, regardless of whether the thin-film technology by vapor deposition or sputtering is used or the green sheet is used and the thick-film technology by the printed conductor paste and co-fire is used. ..

On the other hand, a printed wiring board using an organic material is highly producible in mass production, and since it is easy to perform fine pattern processing and multi-layering, it is widely used not only for consumer equipment but also for industrial equipment. However, in recent years when high-density mounting of electronic devices has progressed and high speed is required, high heat dissipation of printed wiring boards has been required. In addition, a semiconductor integrated circuit (I
C) is smaller and thinner than TSOP (Thin Small)
lOutlinePackage) is often used,
The low thermal expansion of the printed wiring board was required.

That is, the thermal expansion coefficient of the semiconductor integrated circuit package is smaller than that of the conventional silicon due to the miniaturization and thinning, and is about 7 × 10 ⁻⁶ / ° C. ^Therefore , the thermal expansion of the printed wiring board on which it is mounted is About 1.2 ~
Unless it is made smaller than 1.6 × 10 ⁻⁵ / ° C. and approximated, defects such as breakage of the solder connection portion and cracking of the semiconductor integrated circuit package occurred due to thermal expansion difference during mounting.

In order to meet the demand for low thermal expansion of this printed wiring board, attention has been paid to a composite material of ceramics and a thermosetting resin. For example, on the back surface of a copper foil, an alumina (Al ₂ O ₃ ) composition having a thermal expansion coefficient of approximately 7 × 10 ⁻⁶ / ° C. or a cordierite (2MgO · 2Al) having a thermal expansion coefficient of approximately 2.5 × 10 ⁻⁶ / ° C. By forming porous ceramics or porous glass having a composition of ₂ O ₃ · 5SiO ₂ ) by plasma spraying, CVD, sputtering, etc., and laminating it as an outer layer material of a multilayer printed wiring board with a prepreg and an inner layer substrate, Attempts have been made for a low thermal expansion composite material in which the resin from No. 1 is impregnated into the voids to integrate them.

However, according to this method, the porous ceramics or the like on the back surface of the copper foil could not be formed thick. Therefore, when laminated with a thick resin substrate, the thermal expansion coefficient of the entire laminated body could not be reduced.
That is, 0.2m for plasma spraying, CVD, sputtering, etc.
It is difficult to make the thickness more than m, and it cannot be made thicker to handle it while it is welded to the back surface of the copper foil. It is 0.2 mm thick on both sides of the glass epoxy board of 0.6 mm thickness. The coefficient of thermal expansion is 1.3 x 1 when the total thickness is 1.2 mm by laminating through the prepreg of
Compared with the target value of 7 × 10 ^-6 / ° C, which is 0 ^-5 / ° C, it cannot be used much larger.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the problem to be solved is to provide porous ceramics or porous glassy pores welded to the back surface of a copper foil. It is to reduce the coefficient of thermal expansion of the entire substrate while using a composite insulating material layer in which a gap is impregnated with a thermosetting resin. The object of the present invention is to improve the connection reliability with electronic components and prevent damage to electronic components by approximating the thermal expansion coefficient of the entire substrate to the thermal expansion coefficient of the semiconductor integrated circuit TSOP or bare chip IC. It is to provide a composite printed wiring board that can be manufactured.

[0008]

Means for Solving the Problems In order to solve the above problems, the means adopted by the present invention will be described with reference to the reference numerals used in the examples. Composite insulating material layer (1) in which voids of porous ceramics or porous glass are impregnated with thermosetting resin
In a printed wiring board having 3), a base substrate (11) in which voids of porous ceramics are impregnated with a thermosetting resin and a composite insulating material layer (13) are prepreg (1).
4) is a laminated printed wiring board (10) ". Alternatively, "in the printed wiring board, a prepreg (14) including a base substrate (11) and a composite insulating material layer (13) in which one or a combination of a ceramics dense body, 42 nickel iron alloy or aramid fiber reinforced thermosetting resin is combined. ), The composite printed wiring board (10) ”characterized by being laminated by.

[0009]

Function: The composite insulating material layer (13) in which the thermosetting resin is impregnated in the voids of porous ceramics or porous glass adhered to the back surface of the copper foil (12) has a thermal expansion of 5 to 1
It is as small as 0 × 10 ^-6 / ° C and has excellent heat dissipation. The coefficient of thermal expansion of this and the pores of the porous ceramics impregnated with a thermosetting resin is 2.5 to 8 × 10 ⁻⁶ /
℃ base substrate (11) or coefficient of thermal expansion 2.5 ~
Dense ceramic body of 7 × 10 ^-6 / ° C, 42 nickel iron alloy with thermal expansion coefficient of approximately 6 × 10 ^-6 / ° C or aramid fiber reinforced thermosetting with thermal expansion coefficient of 7-10 × 10 ^-6 / ° C Since any one of the resins or the base substrate (11) in which the resins are combined is laminated by the prepreg, the thermal expansion coefficient of the whole is as small as 1 × 10 ⁻⁵ / ° C. or less. Here, the coefficient of thermal expansion of the entire composite printed wiring board (10) is its composition if it is a ceramic or glass material, the void porosity if it is a porous ceramic material or a glass material, and the composite insulating material layer occupying the entire substrate thickness. (1
3) and the thickness of the base substrate (11).

[0010]

EXAMPLES Next, the present invention will be described in detail according to examples. FIG. 1 shows a composite printed wiring board 1 according to the present invention.
A cross-sectional view of the embodiment is shown. In the case of this embodiment, the base substrate (11) is obtained by impregnating pores of porous ceramics with a thermosetting resin. The manufacturing method is as follows. First, a ceramic raw material having a cordierite or alumina composition is kneaded together with a binder, and then formed into a plate by a sheet forming method using a doctor blade or a press forming method. Next, it is fired to obtain a porous ceramic, and the porosity of the porous ceramic is determined by adjusting the firing temperature and time. That is, the porosity is obtained by not completely melting the ceramic particles but by suppressing the melting of only the contact. In this example, the porosity was set to about 30%. 30% is
It was determined by the subsequent impregnation of the thermosetting resin and the desired coefficient of thermal expansion. Then, the porous ceramics is impregnated with epoxy resin which is a thermosetting resin under vacuum, and 120 to 1
The base substrate (11) was obtained by heating at 70 ° C. for 60 to 360 minutes to cure the thermosetting resin. The coefficient of thermal expansion of the base substrate (11) in the case of the cordierite composition is about 3.5 ×
It was 10 ^-6 / ° C. In addition to the above examples, as the thermosetting resin, thermosetting resins generally used for printed wiring board materials such as polyimide resin and triazine resin could be used.

Then, a copper conductor circuit is formed on both sides of the base substrate (11) using the porous ceramics of the cordierite composition by a known pattern forming method to form an inner layer substrate and a glass woven cloth reinforced epoxy resin. Through the prepreg (14), the back surface of the copper foil is welded with porous ceramics or porous vitreous material, and laminated pressing is performed, and through-hole drilling, plating, etching, etc. are appropriately performed, and the composite insulating material layer ( 13) and base substrate (11)
A composite printed wiring board (10) having

As the prepreg (14), a prepreg used for a printed wiring board can be used. However, when the impregnated resin is laminated, the prepreg (14) forms a porous ceramic or porous glassy void gap welded to the back surface of the copper foil. It is necessary to select a resin having a good impregnating property so as to fill it. The glass woven fabric may be a non-woven fabric, and aramid fiber may be used instead of glass, and the material of the fiber is not limited. The lamination press is preferably a low pressure press under vacuum, and an autoclave method is preferable. The reason is that extra pressure is not applied to the ceramics or the like welded to the back surface of the copper foil or the ceramics of the base substrate (11) to damage them.

Composite printed wiring board (10) thus obtained
The coefficient of thermal expansion of is the composition type (A) of the porous ceramics used in the composite insulating material layer (13), its thickness (B), the composition type of the porous ceramics used in the base substrate (11) ( C), its porosity (D), its thickness (D) and the number of intervening 0.1 mm prepregs (E)
Determined by Some examples are shown in Table 1.

Table 1 I II III ───────────────────────────────── (A) Cordierite Alumina Alumina (B ) 0.1mm 0.1mm 0.1mm (C) Cordierite Cordierite Cordierite (D) 0.6mm 1.0mm 0.6mm (E) Both front and back 2 sheets Front and back 2 sheets Total thickness 1 .2mm 1.6mm 1.2mm ───────────────────────────────── Coefficient of thermal expansion 4 × 10 ^-6 / ℃ 7 × 10 ^-6 / ℃ 8 × 10 ^-6 / ℃

Incidentally, the composite printed wiring board (1) of I in Table 1 is
0) has a coefficient of thermal expansion very close to that of a semiconductor bare chip, and is suitable for large chips of 10 mm square or more and flip chip mounting. Further, II and III have a coefficient of thermal expansion close to that of TSOP, and are suitable for mounting TSOP, and have a characteristic of excellent heat dissipation because the surface is alumina. Further, since the composite insulating material layer (13) and the base substrate (11) are both porous and the void gap is impregnated with a thermosetting resin, drilling is easy, but wear of the drill is fast. So it is better to use a diamond drill.
Further, although the four-layer substrate has been described above, the number of conductor layers is not limited to four and may be one or more conductor layers. The structure of the insulating layer is
Considering warpage and the like, it is desirable to have prepreg (14) layers with the same thickness on both sides of the base substrate (11) and also provide the composite insulating material layer (13) on both sides thereof. Also, by using a dense ceramic body such as cordierite, alumina, or mullite, or 42 nickel iron alloy as the base substrate (11), the composite printed wiring board (10) with low thermal expansion can be obtained. If a through-hole is required in the case of a dense ceramics body, a hole larger than the through-hole is previously formed in a portion corresponding to the through-hole in the state of the green sheet, and then fired, and finally after the lamination is completed, the resin is formed. The through hole may be aligned with the hole impregnated with. However, it should be noted that the dense body has a large shrinkage during firing. Further, when using a 42-nickel-iron alloy, it is necessary to form it into a pattern shape in advance as needed before stacking. Further, the base substrate (11) may be made of an aramid fiber reinforced thermosetting resin which has a small coefficient of thermal expansion and does not largely impair the coefficient of thermal expansion after being laminated with the composite insulating material layer (13). Table 2 shows some examples of the type (F) of the ceramic dense body, the nickel iron alloy or the aramid fiber reinforced thermosetting resin, its thickness (G) and the thermal expansion coefficient of the composite printed wiring board (10).

Table 2 IV V VI ───────────────────────────────── (A) Cordierite Cordierite Cordierite (B) 0.1 mm 0.1 mm 0.1 mm (F) Mullite 42 Nickel Iron Aramid Reinforced Resin (G) 0.6 mm 0.25 mm 0.5 mm (E) Both Front and Back 2 Sheets Aramid Reinforced Resin Total Thickness is 1.2mm 0.85mm 1.2mm ───────────────────────────────── thermal expansion coefficient of 5 × 10 ^{- 6} / ° C. 7 × 10 ⁻⁶ / ° C. 8 × 10 ⁻⁶ / ° C. The composite printed wiring board thus obtained is composed of a large number of semiconductor TS.
It is suitable for applications such as multi-chip modules such as memory modules equipped with OPs and bare chip ICs, electronic components such as high heat generation power devices, and mother boats equipped with semiconductor integrated circuit packages.

[0017]

As described in detail above, in the composite printed wiring board of the present invention, the coefficient of thermal expansion can be approximated to that of the semiconductor integrated circuit TSOP and the bare chip, and the connection reliability of the electronic component can be improved and the electronic component can be improved. Can be prevented from being damaged. Further, the type and thickness of the constituent materials can be variously changed, and it is possible to match the thermal expansion with various electronic components and to improve the heat dissipation.

[Brief description of drawings]

FIG. 1 is a plan view showing one embodiment of a composite printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the composite printed wiring board according to the present invention.

[Explanation of symbols]

 10 composite printed wiring board 11 base substrate 12 conductor circuit 13 composite insulating material layer 14 prepreg

Claims (2)

[Claims] 1. A printed wiring board having a composite insulating material layer in which a thermosetting resin is impregnated in the voids of porous ceramics or porous glassy material welded to the back surface of a copper foil, wherein the voids of porous ceramics are provided. A composite printed wiring board, characterized in that a base substrate having a gap impregnated with a thermosetting resin and the composite insulating material layer are laminated by a prepreg. 2. The printed wiring board according to claim 1, wherein a base substrate, in which one or a combination of a ceramics dense body, 42 nickel iron alloy or aramid fiber reinforced thermosetting resin is combined, and the composite insulating material layer are formed by prepreg. A composite printed wiring board characterized by being laminated.