JPH0815768B2 - Laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate used as, for example, a printed wiring board built in a transmitter / receiver in the field of wireless communication or a printed wiring board built in information processing equipment such as a high speed computer and a magnetic device. Regarding the board.

[0002]

2. Description of the Related Art Conventionally, as a base cloth used for the above-mentioned laminated board, for example, style # 108 (thickness 61 μm is generally used.
m, weight 48 gr / m ² , density 60 × 47 pieces / 25.4 m
m), style # 1080 (thickness 53 μm, weight 47 gr /
m ² , density 60 x 47 lines / 25.4 mm), style # 1
16 (thickness 102 μm, weight 105 gr / m ² , density 60 ×
58 pieces / 25.4 mm) glass cloth, etc. are used.
As shown in FIG. 8, a glass cloth 9 woven with a large number of warp threads 9a and weft threads 9b is impregnated with PTFE resin to form a resin cloth 10, and an appropriate number of the resin cloth 10 is laminated to form an outermost layer. The metal foil 11 is arranged on the resin layer to form one laminated plate 12.

[0003]

However, the glass cloth 9 described above has a large gap between the warp threads 9a and the weft threads 9b and a large degree of opening. , The dielectric constant in the volume direction is partially changed, the printed wiring board lacks continuous uniformity of characteristics, and may have a considerable adverse effect in a field having a short wavelength. In addition, the conventional product has a large dimensional deformation that occurs during secondary molding and is not suitable for practical use, so its application is limited to double-sided printed wiring boards.

If the glass cloth 9 has a large opening,
When resin is impregnated, voids containing air are apt to be generated in the thread gap of the glass cloth 9, and if voids remain between the laminated layers, the joining becomes insufficient, the metal foil swells due to thermal expansion at the time of solder bonding, and the resin layer is squeezed between the resin layers. Since peeling occurs, heat resistance and thermal shock resistance during solder bonding are poor. Also, when plating is applied during circuit molding, if the plating solution enters the voids,
The Cu ions contained in the plating solution tend to cause maglation, which deteriorates the insulating property of the substrate. Furthermore, there is a problem in that the chemical solution penetrates during etching due to the decrease in the density of the entire laminated plate 12.

In view of the above problems, the present invention solves the drawbacks of the conventional laminated plate, makes it possible to make the resin content uniform, is excellent in low dielectric constant, high frequency characteristics, dimensional stability, and has a small linear expansion coefficient. The purpose is to provide a laminated plate.

[0006]

According to the invention described in claim 1 of the present invention, the opening between the warp and weft is flattened to about 0.004 mm ² or less, and the thickness is about 0.03 mm to about 0. Glass cloth formed to 12 mm was impregnated with a dispersion of PTFE resin and dried, and then PTFE impregnated into the glass cloth.
After the resin is heated at a temperature higher than the melting point and baked, the above impregnation, drying and baking processes are repeated to form a predetermined resin content, and then the PTFE resin impregnated in the outermost layer is dried at a temperature lower than the melting point. Then, the unbaked resin layer is held as it is, impregnated with a dispersion of PFA resin or FEP resin on the unbaked resin layer and dried, and then heated at a temperature higher than the melting point of the PTFE resin to simultaneously form the upper and lower resin layers. After forming a resin cloth formed by firing and arranging a metal foil on one surface or both surfaces of a laminate formed by polymerizing one or more of the above resin cloths, PT
It is a laminated plate which is heated at a temperature higher than the melting point of the FE resin and pressure-molded.

The invention according to claim 2 of the present invention is, in addition to the structure according to claim 1, the PTFE impregnated after the second time except the dispersion of the PTFE resin impregnated into the glass cloth at the first time. It is characterized by being a laminated plate in which an inorganic substance is mixed in a resin dispersion in an amount of 5 vol% to 25 vol%.

[0008]

According to the present invention, a resin cloth is formed by impregnating a flattened glass cloth with PTFE resin and impregnating the outermost layer with unbaked resin layer with PFA resin or FEP resin. Then, since the laminate is pressure-molded by arranging a metal foil on one side or both sides of a laminate formed by polymerizing an appropriate number of resin cloths, the resin content per unit area is made uniform overall, The dielectric constant in the volume direction becomes constant. In addition, in the high frequency region, low dielectric constant and low dielectric loss tangent can be obtained, continuous uniformity of characteristics can be obtained, and circuit design that maximizes the dielectric efficiency of the circuit can be performed, and high performance is required in the high frequency band. Can be applied to.

Moreover, since the dimensional stability at the time of molding is excellent and the linear expansion coefficient in the thickness direction is small, the joining force between the laminated layers is strong, the heat resistance and the thermal shock resistance at the time of solder bonding are improved, and the immersion of the chemical solution In addition to the prevention of voids, voids do not occur during lamination, and it is possible to reliably prevent swelling of metal foils, interlayer cracks, and interlayer peeling during solder bonding.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawings show a laminated board used as a printed wiring board. In FIG. 1 and FIG. 2, the laminated board 1 is, for example, a warp 2 formed by assembling a large number of glass fibers.
The glass cloth 2 is plain woven with a (warp) and weft 2a (weft), and hydroformed or roll-formed so that the opening between the yarns 2a and 2b is about 0.004 mm ² or less, The glass cloth 2 is flattened in a state of being lost and impregnated with a dispersion of PTFE resin (polytetrafluoroethylene) into a glass cloth 2 having a thickness of about 0.03 mm to about 0.12 mm and dried to obtain the same glass cloth. The PTFE resin impregnated in 2 is heated at a temperature (about 380 ° C.) higher than the melting point (about 327 ° C.) and fired to form the first resin layer 3 in which the glass cloth 2 is impregnated with PTFE resin.

After the above-mentioned impregnation, drying and firing treatments were repeated many times to form a resin content of 63 vol%, as shown in FIG. 3, the outermost layer was impregnated with a PTFE resin dispersion. Is the melting point of the PTFE resin (about 327
Second resin layer 4 holding the unsintered PTFE resin by performing a drying treatment at a temperature lower than (.degree. C.) (for example, about 305.degree. C.).
To form.

Next, as shown in FIG. 4, unbaked PTF is used.
The second resin layer 4 holding the E resin is impregnated (coated) with a dispersion of PFA resin (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or FEP resin (tetrafluoroethylene / hexafluoropropylene copolymer). And dry it, then use PTFE
The second resin layer 4 formed by the unsintered PTFE resin layer and the third resin formed by the PFA resin layer or the FEP resin layer by heating at a temperature (about 380 ° C.) higher than the melting point of the resin (about 327 ° C.)
The resin layer 5 and the resin layer 5 are simultaneously fired to form the resin cloth 6.

Alternatively, the first PT for impregnating the glass cloth 2
Except for the dispersion of FE resin, the dispersion of PTFE resin to be impregnated after the second time is made with 5 v of an inorganic substance such as glass beads and glass milled fiber.
The resin cloth 6 is formed by blending in the range of ol% to 25 vol%.

Next, as shown in FIG. 5, the resin cloth 6
After polymerizing one or more sheets (for example, three sheets) to form a laminate 7, metal foils 8 are arranged on both sides (or one side) of the laminate 7 and the melting point of the PTFE resin (about 327 ° C.). It is heated at a higher temperature (about 380 ° C.) and integrally pressure-molded to form the laminated plate 1 having a thickness of about 0.4 mm.

The glass cloth 2 has a thickness of about 0.03 mm.
The optimum thickness is about 0.12 mm, and when the thickness is less than about 0.03 mm, the dough becomes soft and the handling during molding becomes poor. If the thickness exceeds about 0.12 mm, the PTFE resin has poor permeability and cannot be uniformly impregnated.

The flatness is the width w of the yarn and the thickness t of the yarn.
, Flatness y, y = w / t = 8 to 20 is optimum, and if the relation of y <8 is satisfied, the openness becomes unnecessarily large and commercial glass cloth cannot be applied, y> 20 In relation to the above, the yarn is too thick and it is difficult to plain weave the glass cloth 2.

The degree of opening (gap) is the gap δ between the yarns.
And the yarn thickness t are preferably δ <t, and a predetermined flatness y can be maintained to prevent the gap δ from unnecessarily increasing.

It is suitable to mix the inorganic substance in the range of 5 vol% to 20 vol%, and if it exceeds 25 vol%, the penetration of the plating solution and the heat resistance will be deteriorated, and the volatility will be 5 vol%.
If it is less than the above range, the effect of the composition cannot be expected.

As a comparative example of the laminated plate 1 formed as described above, for example, as shown in Table 1, there are 60 warps, 56 wefts, a yarn flatness y = 8, and an opening degree of about 0.001.
and open繊偏Tairaka in mm ^2, after impregnation and drying a dispersion of PTFE resin into a glass cloth is formed with a thickness of approximately 0.1 mm (see FIG. 1), to form a PFA resin layer of unfired the outermost resin After forming a resin cloth having a retention rate of 63 vol% and arranging metal foil (for example, copper foil) with a thickness of about 18 μm on the upper and lower surfaces of a laminate formed by polymerizing 6 pieces of the resin cloth, the molding temperature is set. Is set to 380 ° C and the molding pressure is 35 kg.
A laminated board A of the embodiment is manufactured by setting f / cm ² and press-molding it to a thickness of about 0.8 mm.

On the other hand, as shown in FIGS. 7 and 8, 62 warps, 59 wefts, a yarn flatness y = 7, a mesh opening of about 0.008 mm ² , and a thickness of about 0.1 mm were formed. After impregnating a glass cloth (see Fig. 7) with a dispersion of PTFE resin and drying it, a PFA resin layer is formed on the outermost layer to form a resin cloth with a resin retention rate of 63 vol%, and six resin cloths are polymerized. About 18μ thick on both upper and lower sides of the laminated body
m of metal foil (for example, copper foil) was placed, then the molding temperature was set to 380 ° C., the molding pressure was set to 35 kgf / cm ² , and pressure molding was performed to a thickness of about 0.8 mm. The laminated board B is manufactured.

The following Table 1 shows the results of testing the laminate A of the above example and the laminate B of the comparative example under the same conditions.

[0022]

[Table 1]

Further, when the dielectric constants of the laminated plate A of the example and the laminated plate B of the comparative example are compared, it is obtained by the following mathematical expression [Formula 1] (Dr. Newton's compound rule is cited).

[0024]

[Equation 1]

As is clear from Table 1 above, the laminated plate B of the comparative example has a large difference in the measured values at the intersections of the yarns and the openings, but the laminated plate A of the example.
Is stable with almost no difference in measured values in any part.

Further, the laminated plate B is, as shown in FIG.
Since the ratio of TFE resin and glass fiber is largely different and the resin content rate per unit area is non-uniform,
A large difference occurs in the dielectric constant εr immediately below the A circuit and immediately below the B circuit.

On the other hand, in the laminated board A, as shown in FIG. 6, since the resin content per unit area is entirely uniform,
The dielectric constant εr is constant just below the A circuit and just below the B circuit, and the dielectric constant of the example A is lower than that of the laminated plate B of the comparative example.

As described above, since the glass cloth 2 constituting the laminated plate 1 is spread and flattened, the resin content per unit area is made uniform and the dielectric constant in the volume direction becomes constant. In addition, in the high frequency region, low dielectric constant and low dielectric loss tangent can be obtained, continuous uniformity of characteristics can be obtained, and circuit design that maximizes the dielectric efficiency of the circuit can be performed, and high performance is required in the high frequency band. Can be applied to.

Moreover, since the dimensional stability during molding is excellent and the linear expansion coefficient in the thickness direction is small, the joining force between the laminated layers is strong, the heat resistance and the thermal shock resistance at the time of solder bonding are improved, and the immersion of the chemical solution In addition to the prevention of voids, voids do not occur during lamination, and it is possible to reliably prevent swelling of metal foils, interlayer cracks, and interlayer peeling during solder bonding.

Further, the linear expansion coefficient can be further reduced by adding an appropriate amount of fine particles such as glass beads and glass milled fibers to the PTFE resin constituting the laminated board 1, and electronic parts can be mounted on the printed wiring board. It can be applied to double-sided boards or multilayer boards that are desired to be surface-mounted.

The present invention is not limited to the configuration of the above embodiment.

[Brief description of drawings]

FIG. 1 is a plan view showing a plain weave state of a glass cloth constituting a laminated plate of the present invention.

FIG. 2 is a vertical sectional side view of a glass cloth showing a laminated state of a first resin layer.

FIG. 3 is a vertical sectional side view of a glass cloth showing a laminated state of a second resin layer.

FIG. 4 is a vertical cross-sectional side view of a resin cloth showing a laminated state of a second resin layer and a third resin layer.

FIG. 5 is a vertical cross-sectional side view of a laminated plate showing a polymerized state of resin cloth.

FIG. 6 is a vertical cross-sectional side view showing a laminated board A of an example.

FIG. 7 is a plan view showing a plain weave state of a glass cloth used for a laminated board B of a comparative example.

FIG. 8 is a vertical sectional side view showing a laminated board B of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laminated board 2 ... Glass cloth 2a ... Warp 2b ... Weft 3 ... 1st resin layer 4 ... 2nd resin layer 5 ... 3rd resin layer 6 ... Resin cloth 7 ... Laminated body 8 ... Metal foil

Claims (2)

[Claims] 1. A glass cloth formed by flattening the openings between warp and wefts to about 0.004 mm ² or less and having a thickness of about 0.03 mm to about 0.12 mm is impregnated with a dispersion of PTFE resin. And dry it, then impregnate the glass cloth with PTF
The E resin is heated at a temperature higher than the melting point and baked, and the above-mentioned impregnation, drying and baking are repeated to form a predetermined resin content, and then the PTFE resin impregnated in the outermost layer is dried at a temperature lower than the melting point. After being treated and kept unfired, the unfired resin layer is impregnated with a dispersion of PFA resin or FEP resin and dried, and then heated at a temperature higher than the melting point of the PTFE resin to form upper and lower resin layers. After forming a resin cloth formed by co-firing and arranging a metal foil on one surface or both surfaces of a laminate formed by polymerizing one or more of the above resin cloths, PT
A laminated plate which is heated at a temperature higher than the melting point of the FE resin and pressure-molded. 2. The first PTFE impregnated into the glass cloth
Except for resin dispersion, 5% by volume of inorganic material is added to the PTFE resin dispersion that is impregnated after the second time.
The laminated plate according to claim 1, wherein the laminated plate is mixed in an amount of -25 vol%.