JP4260789B2 - Method of using printed circuit board for millimeter wave band communication - Google Patents

Description

This onset Ming relates to a method of using the PCB in millimeter-wave band communications.

  Applications of frequencies in the high frequency band of the GHz band include those shown in Table 1, and in addition to those listed in Table 1, in automobile collision prevention systems using millimeter wave radar, it is expected to be 70 GHz or higher. .

Substrates used for printed circuits and antennas for high frequency bands as described above are required to have a low dielectric constant and a low dielectric loss tangent, and a glass cloth / fluorine resin substrate that satisfies these requirements is used as a high frequency band substrate. It is used a lot. In recent years, a base material that does not use a glass cloth having a high dielectric constant and a heavy weight has been studied. For example, a substrate material in which an aramid fiber nonwoven fabric is impregnated with an epoxy resin has been proposed (for example, patents). Reference 1).
JP 2002-3626 A

However, the substrate material obtained by impregnating an aramid fiber non-woven fabric of Patent Document 1 with an epoxy resin has a low dielectric constant because glass cloth is not used, but the property that aramid fibers have high hygroscopicity (water absorption). Therefore, there is a problem that heat resistance to moisture absorption is low and the dielectric loss tangent is also higher than that using glass cloth. Furthermore, the glass cloth / fluororesin substrate has a disadvantage that the dielectric loss tangent increases as the frequency band increases, and the communication loss increases.
The present invention has been made in view of such circumstances, and provides a substrate material and a printed circuit board that are excellent in solder heat resistance, suppress an increase in dielectric loss tangent to an increase in frequency band, and suppress communication loss to a low level. The purpose is that.

The present invention, Ri Do from port Riarireto based liquid crystal polymers, at least a substrate material content of the fluoroplastic resin in nonwoven heat resistance is imparted is impregnated or laminated fluoroplastic such that 50 to 90% by weight by heating on one side, about the method of using a printed circuit board a metal foil to form a desired conductor pattern is arranged on the millimeter-wave band communications.
According to this method , since the non-woven fabric made of the polyarylate-based liquid crystal polymer having low water absorption is impregnated or laminated with the low water absorption fluororesin, the water absorption rate can be kept low. Furthermore, since more heat resistance pressurized heat the nonwoven fabric is applied, solder heat resistance is improved. Further, since the increase in the dielectric loss tangent in the millimeter wave band of 30 GHz or more is low in the liquid crystal polymer, the increase in the dielectric loss tangent with respect to the increase in the frequency band is suppressed.

In the above substrate material, the content of the fluororesin Ru 50-90% der. If the fluororesin content is less than 50% by weight, the water absorption rate and the dielectric loss tangent increase. If it is more than 90% by weight, the fluororesin content is too high, resulting in a large dimensional change when forming a printed board. Therefore, it is not preferable.

Also, at least on one side of the upper Symbol substrate material, a metal foil to form a desired conductor pattern is high.
According to this printed circuit board, since the substrate material is used, the water absorption rate is kept low, the solder heat resistance is good, and the increase in the dielectric loss tangent with respect to the increase in the frequency band is suppressed.

The printed board preferably has a fluororesin adhesive layer formed between the substrate material and the metal foil.
Since the fluororesin adhesive layer is formed between the substrate material and the metal foil, the anchoring effect of the fluororesin improves the adhesion between the metal foil and the fluororesin, resulting in a printed circuit board with good adhesion. can get.

According to the present invention, excellent in solder heat resistance, it is possible to suppress the increase in the dielectric loss tangent obtain suppressed low communication loss for increasing the frequency band.

Figure 1 is a sectional view showing a printed circuit board 1 that is used in the present invention. The printed circuit board 1 includes copper foils 4 as metal foils that form a predetermined conductor pattern on both sides of the substrate material 2, and the fluororesin adhesive layer 3 is interposed between the substrate material 2 and the copper foil 4. Is formed. The substrate material is shown as one layer, but any number of layers may be used.

The substrate material 2 is made of a polyarylate-based liquid crystal polymer, and a non-woven fabric imparted with heat resistance by heating (hereinafter also simply referred to as “liquid crystal polymer non-woven fabric”) is impregnated with a fluororesin.
The liquid crystal polymer non-woven fabric which is the base material of the substrate material 2 is prepared by dispersing a polyarylate liquid crystal polymer from a polyarylate liquid crystal polymer using a known wet papermaking method, for example, in a solvent such as water. The slurry is made into a desired basis weight and is once used as a base paper through a heat drying process. The sheet heating and pressing processing (calendering) to form a non-woven fabric is produced by Rukoto to heat the nonwoven fabric.

Polytetrafluoroethylene (PTFE) is used as the fluororesin impregnated into the liquid crystal polymer nonwoven fabric. In addition, for example, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-per A fluoroalkoxyethylene copolymer (PFE), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or a tetrafluoroethylene-ethylene copolymer (ETFE) can be used.
The content rate of a fluororesin is 50 to 90 weight%. If the fluororesin content is less than 50% by weight, the water absorption rate and the dielectric loss tangent increase. If it is more than 90% by weight, the fluororesin content is too high, resulting in a large dimensional change when forming a printed board. Because.

The fluororesin adhesive layer 3 is formed between the substrate material 2 and the copper foil 4, and the adhesion between the copper foil 4 and the fluororesin is improved by the anchor effect of the fluororesin. A good printed circuit board 1 is obtained.
Although the same thing as the above can be used for the fluororesin of the fluororesin adhesive layer 3, the PFA film is laminated | stacked and used for the board | substrate material 2 here.

The printed board 1 has a low water absorption by a substrate material 2 formed by impregnating or laminating a non-woven fabric made of a polyarylate-based liquid crystal polymer having a low water absorption with a low water absorption fluororesin. Furthermore, since more heat resistance pressurized heat is applied to the nonwoven fabric, excellent solder heat resistance. In addition, since the increase in the dielectric loss tangent in the millimeter wave band of 30 GHz or more is low in the liquid crystal polymer, the increase in the dielectric loss tangent with respect to the increase in the frequency band is suppressed. Furthermore, since the printed circuit board 1 has the fluororesin adhesive layer 3 formed between the substrate material 2 and the copper foil 4, the anchoring effect of the fluororesin improves the adhesion between the copper foil 4 and the fluororesin. Excellent adhesion.

The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the present invention.
Although the copper foil 4 is used as the metal foil, a metal foil such as aluminum, iron, stainless steel, nickel, or an alloy thereof may be used.
In the above embodiment, the substrate material 2 is formed by impregnating a liquid crystal polymer nonwoven fabric with a fluororesin. However, instead of impregnating the fluororesin, for example, a PFA film may be laminated on the liquid crystal polymer nonwoven fabric.
In the above embodiment, the PFA film is laminated on the substrate material 2 as the fluororesin adhesive layer 3, but not only the mode in which the fluororesin film is laminated to form the adhesive layer, but also the fluororesin, for example, The fluororesin adhesive layer 3 may be formed by impregnating with PTFE.

(Example 1)
A liquid crystal polymer non-woven fabric (Kuraray Co., Ltd. MBBK-52FXSP) was impregnated with PTFE dispersion (Daikin Kogyo Co., Ltd. PTFE dispersion D-70E), dried, and finally impregnated with PFA dispersion (Mitsui DuPont). And a substrate material having a fluorine resin impregnation ratio of 50% by weight was obtained. Copper foil (18 μm thick copper foil CF-T9LP manufactured by Fukuda Metal Foil Powder Co., Ltd.) was placed on the upper and lower surfaces of this substrate material, and fired at a firing temperature of 340 ° C. and a molding surface pressure of 2 MPa for 20 minutes and a reduced pressure atmosphere (10 The printed circuit board of Example 1 was obtained.

(Example 2)
The same liquid crystal polymer non-woven fabric as in Example 1 (Kuraray Co., Ltd. MBBK-52FXSP) is placed on the upper and lower surfaces of a PFA film (Daikin Kogyo Co., Ltd., NEOFLON, thickness 25 μm). A similar copper foil was placed and molded under the same molding conditions as in Example 1 to obtain a printed circuit board of Example 2. In addition, the fluororesin content rate of the printed circuit board of Example 2 is 67 weight%.

(Comparative Example 1)
Example 1 on upper and lower surfaces of a prepreg in which a glass cloth fiber (# 108 glass cloth manufactured by Arisawa Manufacturing Co., Ltd., basis weight 48 g / m ² ) was impregnated with PTFE dispersion (PTFE dispersion 34J manufactured by Mitsui / DuPont Fluorochemical Co., Ltd.) The same copper foil as above was placed and subjected to hot press molding (molding conditions: 385 ° C., 5 MPa, 60 minutes) to prepare a glass fiber cloth reinforced / fluororesin printed circuit board of Comparative Example 1. In addition, the fluororesin content rate of the printed circuit board of the comparative example 1 is 80 weight%.

(Comparative Example 2)
Four prepregs impregnated with the same PTFE dispersion as in Comparative Example 1 are laminated on an aramid fiber non-woven fabric (Aramid fiber paper: THERMOUNT # 80 manufactured by DuPont Teijin Advanced Paper Ltd., basis weight 56 g / m ² ). The copper foil similar to Example 1 was arrange | positioned, and the aramid fiber paper reinforcement / fluororesin printed circuit board of the comparative example 2 was created by carrying out hot press molding (molding conditions: 385 degreeC, 5 Mpa, 60 minutes). In addition, the fluororesin content rate of the printed circuit board of the comparative example 2 is 80 weight%.

  Table 2 shows the measurement results of the dielectric constant and dielectric loss tangent at 10 GHz, the water absorption, and the solder heat resistance after boiling of the printed boards of Examples 1-2 and Comparative Examples 1-2. Moreover, about dielectric loss tangent, it measured also about 6, 12, and 75 GHz, and the result is shown in Table 3 with the result in 10 GHz. As the measurement method, for the dielectric constant and dielectric loss tangent, the disk resonator stripline method was used at measurement frequencies of 6, 10 and 12 GHz, and the Fabry-Perot resonator method was used at 75 GHz. About water absorption and solder heat resistance, JIS-C6481-1996 (copper-clad laminate test method for printed wiring boards) was used.

  As shown in Table 2, the printed circuit boards of Examples 1 and 2 both have a low water absorption rate and good solder heat resistance after boiling. Furthermore, as shown in Table 3, the increase ratios of the dielectric loss tangent at the measurement frequency 75 GHz with respect to the dielectric loss tangent at the measurement frequency 6 GHz of Examples 1 and 2 are 0.9 and 0.9, respectively. Since it is smaller than 16.7 and 4, communication loss in the high frequency band can be kept low.

It is sectional drawing which shows the printed circuit board used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed circuit board 2 Board | substrate material 3 Fluororesin adhesive layer 4 Metal foil (copper foil)

Claims (2)

Ri Do from port Riarireto based liquid crystal polymers, at least on one surface side of the substrate material content of the fluoroplastic resin in nonwoven heat resistance is imparted is impregnated or laminated fluoroplastic such that 50 to 90% by weight by heating, A method of using a printed circuit board on which a metal foil forming a predetermined conductor pattern is disposed for millimeter wave band communication . The method of claim 1, the fluorine resin adhesive layer is formed between the front Stories substrate material and the metal foil.

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