JPH08288718A - Production of strip line cable - Google Patents

Abstract

PURPOSE: To obtain a strip line cable manufacturing method capable of obtaining a strip line cable with high resistance and high reliability. CONSTITUTION: A 1st dielectric base material 12 is prepared. Reactant type hot metal adhesive is applied to one main face of the base material 12. Then a 2nd dielectric base material 18 is prepared and laminated to the other main face of the base material 12. The 1st and 2nd dielectric base materials 12, 18 are stuck to each other at treatable strength by thermal press adhesion. Then the adhesive 19 is completely cured by moisture to form a parallel strip line cable 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a stripline cable, and more particularly to a method for manufacturing a flexible parallel stripline cable used as a high frequency transmission line.

[0002]

2. Description of the Related Art In miniaturized high frequency devices such as mobile phones, coaxial cables have been used as high frequency transmission lines for transmitting high frequency signals. However, the coaxial cable whose characteristic impedance is selected as an important element is unavoidably structurally large in size. Therefore, when a high-frequency device is constructed by incorporating the coaxial cable, an extra space is required in the outer case, and it is difficult to reduce the size of the entire device.

Therefore, recently, a parallel strip line cable has been proposed as a high-frequency transmission line, which has a thickness of about half that of a coaxial cable when the characteristic impedances are the same. The parallel stripline cable includes a pair of wide outer conductors. The pair of outer conductors are arranged so as to face each other with a dielectric having a predetermined thickness interposed therebetween. A narrow central conductor is formed inside the dielectric.

In this case, since the parallel stripline cable is required to have flexibility as the dielectric material, it is preferable to use a plastic material having flexibility. Further, a material having a small dielectric loss is preferable in terms of characteristic impedance. Therefore, an olefin resin such as polypropylene or a fluorine resin is used as such a dielectric material.

By the way, in order to form a parallel stripline cable having such a structure, a step of bonding the dielectric materials to each other is necessary because the central conductor is formed inside the dielectric. However, a dielectric material having a low dielectric loss for obtaining desired characteristics is non-polar, and thus it is difficult to bond it with a normal adhesive. Therefore, in the conventional stripline cable manufacturing method, the dielectric materials may be bonded to each other using a hot melt adhesive.

[0006]

However, in this case, since the dielectric material made of, for example, an olefin resin is not melted or deformed, it is necessary to perform heat fusion at a temperature lower than the melting point of the dielectric material. Therefore, it is necessary to use a hot-melt adhesive having a melting temperature lower than the melting point of the dielectric material, and there is a problem that the heat resistance of the obtained parallel stripline cable becomes low.

Therefore, a main object of the present invention is to provide a method for manufacturing a stripline cable which can obtain a stripline cable having good heat resistance and high reliability.

[0008]

The present invention comprises a step of forming a conductor pattern on one main surface of a dielectric substrate, and a step of applying a reactive hot melt adhesive to one main surface of the dielectric substrate. And a step of laminating another dielectric base material on one main surface of the dielectric base material and thermocompression-bonding the dielectric base material, and manufacturing the stripline cable.

In the step of forming the conductor pattern, it is preferable to form the conductor pattern by etching one main surface of the dielectric substrate having conductor films on both main surfaces.

Another dielectric base material preferably has a conductor film on one main surface, and the other main surface is thermocompression bonded to one main surface of the dielectric base material.

The dielectric substrate is preferably selected from olefin resins and fluorine resins.

Reactive hot melt adhesives include urethane-modified olefin adhesives, polyisocyanate adhesives,
And epoxy adhesives are preferred.

[0013]

With the use of the reactive hot melt adhesive, it is possible to firmly bond the nonpolar and hardly adhesive dielectric base materials to each other at a relatively low temperature. Further, the reactive hot melt adhesive has higher heat resistance and mechanical strength after curing than the conventional hot melt adhesive.

[0014]

According to the present invention, a stripline cable having good heat resistance and high reliability can be obtained. Further, according to the present invention, it becomes easy to manufacture a stripline cable by using a thermoplastic polymer material as a low-dielectric loss material which is non-polar and hardly adheres.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the accompanying drawings.

[0016]

1 is a perspective view showing an example of a parallel strip line cable manufactured by the manufacturing method of the present invention, and FIG. 2 (D) is a sectional view thereof. The parallel stripline cable 10 includes a strip-shaped first dielectric substrate 12. In this embodiment, the first dielectric substrate 12 is made of flexible polypropylene. First dielectric substrate 1
A first conductor layer 14 is formed over the entire surface of the one main surface 2 as a wide outer conductor. On the other main surface of the first dielectric base material 12, a central conductor 16 as a linear conductor pattern having a narrow width is formed in the widthwise central portion thereof from one end to the other end in the longitudinal direction.

A band-shaped second dielectric base material 18 is formed on the other main surface of the first dielectric base material 12. The second dielectric base material 18 is formed of the same material as the first dielectric base material 12. The one main surface of the second dielectric base material 18 and the other main surface of the first dielectric base material 12 are bonded by the adhesive layer 20. A second conductor layer 22 is formed over the entire surface of the other main surface of the second dielectric base material 18 as a wide outer conductor. In this embodiment, the first conductor layer 14, the second conductor layer 22, and the center conductor 16 are each formed of copper, for example.

FIG. 2 is a process schematic view showing an example of the manufacturing method of the present invention. Parallel stripline cable 10
In order to manufacture, first, as shown in FIG.
An elongated strip-shaped first dielectric substrate 12 is prepared. First
The first conductive layer 14 is formed on the dielectric substrate 12 so as to cover the entire one main surface thereof. A conductor layer 15 made of, for example, copper is formed on the other main surface of the first dielectric substrate 12 so as to cover the entire surface thereof.

Next, as shown in FIG. 2B, a central conductor 16 is formed on the other main surface of the first dielectric substrate 12. In this embodiment, the conductor layer 15 on the other main surface of the first dielectric substrate 12 is etched with, for example, ferric chloride solution to remove unnecessary portions, thereby forming the center conductor 16.

Next, as shown in FIG. 2C, a reactive hot melt adhesive 19 is thinly applied to one main surface of the first dielectric substrate 12. In this embodiment, a solution obtained by diluting a urethane-modified olefin adhesive with a solvent is used as the reactive hot melt adhesive 19. The solution of the reactive hot melt adhesive 19 can be applied by a method such as brush coating, spraying, and printing.

The reactive hot melt adhesive 19 is melted by heating and cooled and solidified to obtain handleable strength. After that, the reactive hot melt adhesive 19 becomes to have high strength and heat resistance by forming a crosslinked structure by a chemical reaction. This chemical reaction includes reactions such as heat curing, radiation curing, moisture curing, and ion curing. The urethane-modified olefin adhesive used in this example is a moisture-curable adhesive, and a cross-linking reaction occurs due to the moisture of the adherend or the moisture in the atmosphere.

Further, as shown in FIG. 2C, an elongated strip-shaped second dielectric base material 18 is prepared. A second conductor layer 22 is formed on the second dielectric base material 18 so as to cover the entire one main surface thereof. And the second
The other main surface of the dielectric base material 18 is laminated on the other main surface of the first dielectric base material 12 as indicated by an arrow in FIG.

Then, the laminated first dielectric substrate 12
The second dielectric base material 18 is thermocompression-bonded by being heated and pressed by, for example, a hot press or a laminator. By thermocompression bonding, the first dielectric base material 12 and the second dielectric base material 18 are adhered to each other with a handleable strength. Then, the reactive hot melt adhesive 19 is completely cured by, for example, moisture to form an adhesive layer 20 as shown in FIG. 2 (D). Thus, the parallel stripline cable 10 shown in FIG. 1 is formed.

In this case, the adhesive layer 20 is the center conductor 16
Since it will intervene as a dielectric on top, it must have low dielectric loss. Further, it is preferable to make the film thickness as thin as possible. Further, it needs to have flexibility after curing. As the reactive hot melt adhesive 19 satisfying these conditions, a polyisocyanate adhesive or an epoxy adhesive can be selected in addition to the urethane-modified olefin adhesive.

FIG. 3 is an illustrative view showing a 180 ° peel test. In this test, first, a parallel stripline cable 10 having a total length (L) of 100 mm and a width length (W) of 5 mm is prepared, and one end of the parallel stripline cable 10 is peeled off so that a length (t) becomes 20 mm. did. Next, the first dielectric substrate 12 and the second dielectric substrate 18 that were peeled off were pulled in opposite directions so as to form an angle of 180 °. Then, the first dielectric substrate 12
The tensile force at which the second dielectric substrate 18 peels was measured as the peel strength. Table 1 shows the results. In addition,
In Table 1, the initial value indicates the peel strength at room temperature and atmospheric pressure. Further, 85 ° C. and 100 Hr represent peeling strength after 100 hours under the condition of 85 ° C. In addition, 60
C., 95% RH, 100 Hr means the peel strength after 100 hours under the conditions of 60.degree. C. and 95% relative humidity.

FIG. 4 is an illustrative view showing a bending resistance test. In this test, first, a parallel stripline cable 10 having a predetermined length was prepared. Next, it was folded back so that the bending radius (r) was 5 mm. And
The vicinity of both ends in the length direction of the parallel stripline cable 10 was fixed to a jig of a measuring instrument. And
After the jig was reciprocated 1000 times in the direction indicated by the solid arrow in FIG. 4, changes in the adhesive layer 20 were observed. The results are also shown in Table 1.

Further, Table 1 also shows the results of the heat shock test. What is the heat shock test?
In a test in which the sample was left at 30 ° C. for 30 minutes and then immediately left at 85 ° C. for 30 minutes, the cycle of this was repeated 100 times, and then the change of the adhesive layer 20 was observed.

[0028]

[Table 1]

Next, a comparative example will be described. In the comparative example, first, the same first dielectric substrate 1 as that of the example shown in FIG.
2 and the second dielectric substrate 18 are prepared. In the first dielectric base material 12 and the second dielectric base material 18, the first conductor layer 14 and the center conductor 1 are provided in the same manner as the embodiment shown in FIG.
6 and the second conductor layer 22 are formed.

In this comparative example, a sheet-shaped hot melt adhesive of ethylene-vinyl acetate copolymer having a melting point of 90 ° C. is prepared. Then, the first dielectric base material 12 and the second dielectric base material 18 are laminated with a hot melt adhesive in between, as in the case shown in FIG. 2C, and thermocompression bonded by a laminator. It Then, by cooling and solidifying, a parallel strip line cable of a comparative example is formed.

Also in this comparative example, 180 °
A peeling test, a bending resistance test and a heat shock test were performed. The results are also shown in Table 1.

As shown in Table 1, the parallel stripline cable 10 of the embodiment shown in FIG.
A peel strength of 2.5 to 3 times was obtained. The parallel stripline cable 10 of the embodiment shown in FIG. 1 showed almost no deterioration in peel strength even after being subjected to heating and humidifying conditions.

Further, as shown in Table 1, in the parallel stripline cable 10 of the embodiment shown in FIG. 1, no peeling of the adhesive layer was observed after the bending resistance test and the heat shock test.

As described above, according to the manufacturing method of the embodiment shown in FIG. 1, it is possible to obtain the parallel stripline cable 10 having higher peel strength, better heat resistance and durability and higher reliability than the conventional one. .

Further, according to the reactive hot melt adhesive 19, thermoplastic polymer materials (for example, polypropylene) which are non-polar and hardly adherent and have a low dielectric loss material can be firmly adhered to each other at a relatively low temperature. You can for that reason,
It becomes easy to manufacture the parallel stripline cable 10 by using such a polymer material as the first dielectric base material 12 and the second dielectric base material 18. Further, by using such a polymer material as the first dielectric base material 12 and the second dielectric base material 18 to form the parallel stripline cable 10, a characteristic impedance equivalent to that of a conventional coaxial cable can be obtained. Obtainable. Also,
This example uses a flexible thermoplastic polymeric material such as polypropylene and a reactive hot melt adhesive such as a flexible urethane modified olefinic adhesive, thus providing flexible parallel strips. The line cable 10 can be obtained.

Further, by using the reactive hot melt adhesive 19, the thermocompression bonding step can be carried out in a short time.

In order to improve the adhesive force, the adhesive surfaces of the first dielectric base material 12 and the second dielectric base material 18 are
It is preferable to perform surface treatment before applying the reactive hot melt adhesive. As the surface treatment method in this case,
Corona discharge treatment, plasma treatment, sputter etching treatment, etc. are suitable.

Further, the reactive hot melt adhesive is not limited to the urethane-modified olefin adhesive, but an isocyanate adhesive, an epoxy adhesive or the like may be used.

Furthermore, the first dielectric substrate 12 and the second dielectric substrate 12
The dielectric base material 18 is not limited to polypropylene, and other olefin resin may be used, and further, fluorine resin may be used.

In addition, the parallel strip line cable 10
Is not limited to be given by applying a solution,
For example, a sheet-shaped adhesive may be applied so as to be laminated.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a parallel stripline cable manufactured by a manufacturing method of the present invention.

FIG. 2 is a process schematic view showing an example of the manufacturing method of the present invention.

FIG. 3 is an illustrative view showing a 180 ° peel test.

FIG. 4 is an illustrative view showing a bending resistance test.

[Explanation of symbols]

 10 Parallel Stripline Cable 12 First Dielectric Substrate 14 First Conductor Layer 16 Center Conductor 18 Second Dielectric Substrate 19 Reactive Hot Melt Adhesive 20 Adhesive Layer 22 Second Conductor Layer

Claims (5)

[Claims] 1. A step of forming a conductor pattern on one main surface of a dielectric base material, a step of applying a reactive hot melt adhesive to one main surface of the dielectric base material, and one of the dielectric base materials. A method for manufacturing a stripline cable, comprising the step of laminating another dielectric base material on the main surface and thermocompression-bonding it. 2. The stripline cable according to claim 1, wherein in the step of forming the conductor pattern, the conductor pattern is formed by etching one main surface of a dielectric substrate having conductor films on both main surfaces. Manufacturing method. 3. The dielectric base material according to claim 1, wherein the other dielectric base material has a conductor film on one main surface, and the other main surface is thermocompression bonded to one main surface of the dielectric base material. A method for manufacturing a stripline cable according to. 4. The method of manufacturing a stripline cable according to claim 1, wherein the dielectric substrate is selected from olefin resins and fluorine resins. 5. The reactive hot melt adhesive is selected from urethane-modified olefin-based adhesives, polyisocyanate-based adhesives, and epoxy-based adhesives. A method for manufacturing a stripline cable according to.