JPH1022595A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To put the thermal expansion coefficients of an electronic component and a printed wiring board at approximate values, by forming terminal plugs for surface mounting so that they may be orthogonal to the direction of threads where the weave density is large. SOLUTION: For example, in a cloth 0.1mm thick, a laminate where glass cloth base material is lined with copper is manufacture, using the glass cloth which is woven so that the threads ma be sixty five pieces in longitudinal direction and fifty five pieces in lateral direction, or sixty seven pieces in longitudinal direction and fifty pieces in lateral direction, as regards the area of 25mm square. This way, a printed wiring board for mounting electronic components is manufactured, using a material for a laminate lined with copper which is manufactured, with the glass cloth, where the weave density is different between the longitudinal direction and the lateral direction, as the base material. At that time, the arrangement of all the terminal plugs of electronic components is designed so that it may be orthogonal to the thread in the direction where the weave density is high. Hereby, the thermal expansion coefficients of the printed wiring board and the electronic component are made approximate values, by which the reliability on connection of the terminal plugs can be improved and also the yield in mounting can also be made good.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board for mounting electronic components and having a terminal plug for surface mounting.

[0002]

2. Description of the Related Art As a substrate for a printed wiring board, a laminate made of a fiber base material and a thermosetting resin is widely used. As the fiber base material, paper, woven fabric, and the like are generally used. However, a so-called glass cloth base material laminate made of glass fiber cloth (hereinafter referred to as glass cloth) has good heat resistance. It is optimal as a substrate material for printed wiring boards used in computers and the like that require reliability. Table 1 shows the main glass cloths currently used.

[0003]

[Table 1] 分類 UL classification Used thread density (line / 25mm) Thickness (mm) Mass (g / m ² ) ２８ 7628 G75 × G75 42 × 32 0.180 203 G75 × G75 44 × 34 0.180 209 G75 × G72 43 × 33 0.180 211 ─────────────────────────── ───────── 2116 E225 × E225 67 × 50 0.100 104 E225 × E225 60 × 58 0.100 104 E225 × E225 65 × 55 0.100 108 E225 × D450 60 × 64 0.09 85 ──────── ──────────────────────────── 1080 D450 × D450 60 × 48 0.055 48 D450 × D450 70 × 60 0.065 58 ───── ────── １０６ 106 D900 × D900 56 × 56 0.035 25 ━━━━━━━━━━━━━━━━━ ━━━━━━━━━━━━━━━━━━━

[0004] The woven density of the glass cloth used as the base material of the laminate is
For example, in a cloth having a thickness of 0.1 mm, the standardization is such that 60 warp yarns and 58 weft yarns per 25 mm (see UL classification 2116).

[0005]

SUMMARY OF THE INVENTION Electronic components have become smaller,
As mounting density has been increased, mounting techniques of a surface mounting type have been increasing in mounting technology. For this reason, the form of the package has changed from an insertion type DIP (dual inline package) or the like to a SOP (small outline package), a TSOP (thin small outline package), or the like. The thermal expansion coefficient of the substrate did not matter so much because DIP etc. were insertion type, but SOP, TSOP
And the like are surface mounting, and if the thermal expansion coefficients of the electronic component and the printed circuit board are not close to each other, the mounting yield is deteriorated, and adverse effects such as deterioration in reliability are caused.

In a memory having a capacity of 4 megabytes, the thermal expansion coefficient of the package is 11 to 13 ppm / ° C., and the allowable value of the thermal expansion coefficient of the printed wiring board is 14 to 1 ppm.
6 ppm / ° C. The thermal expansion coefficient of a general FR-4 level printed circuit board is 15 to 16 ppm / ° C., which is a value close to an allowable value. However, the capacity of the current memory tends to increase from 16 megabytes to 64 megabytes, and the corresponding allowable value of the thermal expansion coefficient of the printed wiring board needs to be 10 ppm / ° C. or less.

[0007] Further, as the printed wiring board for liquid crystal becomes larger and the frame becomes narrower, a narrow and narrow printed wiring board sandwiching the liquid crystal panel is required. This wiring board has been developed with the mounting technology of connecting the liquid crystal glass part and the TCP (tape carrier package) collectively. If the thermal expansion coefficient in the length direction is not close to that of the liquid crystal glass part, the TCP will be distorted, Reliability deteriorates.

As described above, the connection between the electronic component and the printed wiring board is required to have higher reliability as the wiring has a finer pitch. However, there are differences in characteristics due to different materials of the printed wiring board and the electronic component, and it is difficult to make the printed wiring board have the same thermal expansion coefficient as the electronic component. The present invention is intended to solve such a problem, and provides a printed wiring board having good connection reliability with an electronic component.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a printed wiring board obtained from a laminated board based on a glass cloth having different weaving densities in the vertical and horizontal directions. This is a printed wiring board formed so as to be orthogonal to the large thread direction.

The coefficient of thermal expansion of a composite material such as a laminate is
The properties are determined by the volume fraction of the constituent materials. The thermal expansion coefficient of the glass cloth is very small, 1/10 or less of that of the thermosetting resin, so that the thermal expansion coefficient in the direction of increasing the amount of glass per unit sectional area can be reduced.

The warp, which is the longitudinal direction of the glass cloth, is the machine direction when weaving the glass cloth, is sufficiently stretched and woven, and is woven in a form stretched as compared with the weft. For this reason, since the weave shrinkage amount per unit area is small, the coefficient of thermal expansion at the time of heating also has a lower value than that of the weft. Therefore, if the weaving density in the vertical direction is increased and the terminal plug for surface mounting is formed so as to be orthogonal to the vertical direction, the effect is further enhanced.
The surface mount terminal plug is a pad for connection with TCP or the like, and is formed by etching a metal foil such as a copper foil.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As a thread of a glass cloth to be used,
Usually, a thread of E glass is used. When a lower coefficient of thermal expansion is required, S glass or D glass yarn is used.
And, for example, in a cloth having a thickness of 0.1 mm, 2
For 5 mm, a glass cloth-based copper-clad laminate is manufactured using a glass cloth woven so as to be 65 in the vertical direction, 55 in the horizontal direction, or 67 in the vertical direction and 50 in the horizontal direction. I do. The present invention can be applied to a multilayer printed wiring board.
Cloths having different weaving densities in the vertical and horizontal directions are used as a base material of an adhesive prepreg for bonding an inner layer plate and an outer layer material of a multilayer printed wiring board. Then, the adhesive prepreg is arranged such that the yarn direction of the base material is the same as the yarn direction of the base material of the inner layer plate.

A printed wiring board for mounting electronic components is manufactured using the material for a copper-clad laminate manufactured as described above. At that time, the arrangement of all the terminal plugs of the electronic component is designed so as to be orthogonal to the yarn in the direction of higher weaving density.

[0014]

【Example】

Example 1 Weaving density of S glass thread was 65 threads / 25 mm in the longitudinal direction.
A glass cloth (0.1 mm thick) for an electrical insulating material woven in a horizontal direction of 55/25 mm was prepared. 100 parts (parts by weight, hereinafter the same) of an epoxy resin (trade name: Epicoat E5048, manufactured by Yuka Shell Epoki Co., Ltd.) and a phenol novolak resin (trade name: TD-, manufactured by Dainippon Ink and Chemicals, Inc.) 2131) 35
Varnish consisting of 0.15 parts of phenylimidazole and 40 parts of methyl ethyl ketone was impregnated and dried by heating to prepare a semi-cured prepreg. The four prepregs are stacked so that the directions of the glass cloths are the same, and a copper foil having a thickness of 18 μm is stacked on the outermost layer.
By heating and pressing for 0 minutes, a copper-clad laminate was manufactured. Further, the obtained copper-clad laminate is used as an inner layer plate, the prepreg is used as an adhesive prepreg, and the inner layer substrate and the adhesive prepreg substrate are arranged so that the yarn directions are the same. 4) Printed wiring board was manufactured. 4 for LCD
The layer printed wiring board has a width of 10 with the length in the warp direction.
mm, and a length of 240 mm, in which twelve TCP connection terminals are arranged in the length direction, and terminal plugs are provided so as to be orthogonal to the length direction.

Example 2 The glass yarn was changed to E glass yarn, and the weaving density was changed to 67 in the machine direction.
A copper-clad laminate and a 4-layer printed wiring board for LCD were manufactured in the same manner as in Example 1 except that the number of wires / 25 mm and the width in the horizontal direction were 50 wires / 25 mm.

Comparative Example 1 Using S glass thread, the weaving density was 60 in the longitudinal direction / 25 m
m, and a copper-clad laminate was manufactured in the same manner as in Example 1 except that the width was 58 lines / 25 mm, and a terminal plug was provided in parallel with the warp direction of the glass cloth.
A four-layer printed wiring board was manufactured.

Comparative Example 2 The same as Example 1 except that the length direction of the four-layer printed wiring board for LCD was set to the weft direction.

Comparative Example 3 The glass yarn was changed to E glass yarn, and the weaving density was changed to 60 in the machine direction.
A copper-clad laminate was manufactured in the same manner as in Example 1 except that the number of wires / 25 mm and the width in the direction of 58 wires / 25 mm were used, and a terminal plug was provided in parallel with the warp direction of the glass cloth. Thus, a four-layer printed wiring board for LCD was manufactured.

Test 1 Copper foil was removed by etching from the obtained copper-clad laminate.
The coefficient of thermal expansion was measured by TMA (thermomechanical analysis). Table 2 shows the results. The unit of the thermal expansion coefficient is pp
m / ° C. Comparative Example 2 is the same material as in Example 1.

[0020]

[Table 2] Example 1 Comparative Example 1 Example 2 Comparison Example 3 ──────────────────────────────────── Warp direction 8.5 10.5 14.5 16 .2 Weft direction 11.2 10.9 17.5 17.0 mm ━━

Test 2 Using a 4-layer printed wiring board for LCD, a TCP connection experiment (the number of test pieces (= n) was 5, 12 TCPs for each test piece, and a connection tool temperature of 307) At 20 ° C. for 20 seconds), and the mounting yield at the time of mounting connection was examined. In addition, a temperature cycle test of -65 ° C to + 80 ° C was performed to check for disconnection. Table 3 shows the results. Table 3
The denominator of the number indicates the number n of the test pieces tested, and the numerator indicates the number of disconnected test pieces.

[0022]

[Table 3] Example 1 Comparative Example 1 Comparative Example 2 Example 2 Comparative Example 3 {Mounting yield (%) 100 100 98 85 75}温度 Temperature cycle test 50 cycles No abnormality No abnormality No abnormality No abnormality No abnormality 100 cycles No abnormality No abnormalities No abnormalities No abnormalities 2/5 200 cycles No abnormalities No abnormalities No abnormalities No abnormalities 4/5 300 cycles No abnormalities No abnormalities No abnormalities 2/5 5/5 400 cycles No abnormalities No abnormalities 1/5 5/5 5 / 5 500 cycles No abnormality 1/5 2/5 5/5 5/5 600 cycles No abnormality / 5 3/5 5/5 5/5 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

From the results of Test 1 (Table 2), it was found that in Examples 1 and 2 where the weaving density in the warp direction was increased,
It can be seen that the coefficient of thermal expansion in the warp direction is small. Example 1 and Comparative Example 2 used the same glass material. In Example 1 in which the weaving density in the vertical direction was larger than that in the horizontal direction and the terminal plug was provided so as to be orthogonal to the vertical direction, test 2 It can be seen that the results of the temperature cycle test are much better than Comparative Example 2 in which the terminal plugs of Comparative Example 2 having the same vertical and horizontal weave densities were provided so as to be parallel to the vertical direction with the higher weave density. . The same can be said for Example 2 and Comparative Example 3 using E glass thread. Example 2 is inferior to Example 1 using S glass,
It can be seen that both the mounting yield and the temperature cycle test are much better than Comparative Example 3 of the same material as in Example 2.

[0024]

According to the present invention, the connection reliability of the terminal portion is greatly improved, and the mounting yield is also improved.

Claims (2)

[Claims] 1. A printed wiring board obtained from a laminated board based on glass cloth having different weaving densities in a longitudinal direction and a lateral direction, wherein a terminal plug for surface mounting is arranged so as to be orthogonal to a yarn direction having a high weaving density. Printed wiring board formed. 2. A printed wiring board obtained from a laminated board based on a glass cloth having a weaving density in a longitudinal direction larger than a weaving density in a lateral direction, wherein a terminal plug for surface mounting is formed so as to be orthogonal to the longitudinal direction. Printed wiring board.