JP7330556B1 - TRANSMISSION LINE AND METHOD FOR MANUFACTURING TRANSMISSION LINE - Google Patents

Abstract

An object of the present invention is to provide a transmission line that has a shielding performance, is thin enough to save space, and has a structure capable of supporting high-speed transmission with little transmission loss. A transmission line (20) includes a first conductor (31) composed of a transmission line conductor (32) and a ground conductor (33), a first base (34) on which the first conductor (31) is formed, and a coverlay (35) covering the transmission line conductor (32). a second conductor 41 formed on a second substrate 42, a first shield 40 formed on a second substrate 42, a third conductor 46 formed on a third substrate 47, a second shield 45; the first substrate is thermocompression bonded to the second substrate; the third substrate is thermocompression bonded to the coverlay 34; the second conductor 41 and the third conductor 46 is arranged so as to surround the transmission line conductor 32 and is ultrasonically bonded to each other, and the second conductor 41 is configured such that the folded end overlaps the ground conductor 33 and is ultrasonically bonded. [Selection drawing] Fig. 1

Description

The present invention relates to transmission lines used in electronic equipment.

Conventionally, a flexible dielectric body (liquid crystal polymer), a linear signal line provided in the dielectric body, and a signal line provided in the dielectric body and facing the signal line and an auxiliary ground conductor provided on the opposite side of the ground conductor with respect to the signal line in the normal direction of the main surface of the dielectric element, in a plan view from the normal direction and two main portions sandwiching the signal line and extending along the signal line, and a bridge portion connecting the two main portions and crossing the signal line. and a via-hole conductor electrically connecting the auxiliary ground conductor and the ground conductor, wherein the signal line and the auxiliary ground conductor are connected in the normal direction. A high-frequency signal line has been proposed in which the interval is smaller than the interval between the signal line and the ground conductor (Patent Document 1: Utility Model Registration No. 3173143). In addition, a transmission line having a structure in which two conductors and a third conductor are arranged so as to surround the transmission line conductor and are ultrasonically bonded has been proposed (Patent Document 2: Japanese Patent No. 6507302; Patent Document 3: Japanese Patent No. 6611293). Publication, Patent Document 4: Japanese Patent No. 6850501).

Utility Model Registration No. 3173143 Japanese Patent No. 6507302 Japanese Patent No. 6611293 Japanese Patent No. 6850501

BACKGROUND ART Transmission lines used in electronic devices are required to have a shielding performance, a thin structure for space saving, and a structure with little transmission loss for high-speed transmission.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transmission line that has shielding performance, is thin enough to save space, and has a structure with little transmission loss that is compatible with high-speed transmission.

As one embodiment, the above problem is solved by means of solution as disclosed below.

A transmission line according to the present invention includes a first conductor composed of a transmission line conductor and a pair of ground conductors respectively adjacent to an input end and an output end of the transmission line conductor, and a first base on which the first conductor is formed. a coverlay covering the transmission line conductor; a first shield having a second conductor formed on a second substrate; and a second shield having a third conductor formed on a third substrate; is thermocompression bonded to the first substrate, the first substrate is thermocompression bonded to the second substrate, the third substrate is thermocompression bonded to the coverlay, and the second The conductor and the third conductor are arranged so as to surround the transmission line conductor and are ultrasonically bonded to each other, and the folded end of the second conductor is ultrasonically bonded so as to overlap the ground conductor. characterized by

According to this configuration, since the transmission line conductor is surrounded by the second conductor and the third conductor, necessary shielding performance can be obtained. Then, the folded end portion can be formed into a thin structure corresponding to space saving by combining thermocompression bonding and ultrasonic bonding. As an example, the transmission line conductors are formed at first intervals, and the second conductors are formed with through holes at second intervals at positions overlapping the ground conductors in bottom view.

A method of manufacturing a transmission line according to the present invention includes a first conductor formed of a transmission line conductor and a pair of ground conductors respectively adjacent to an input end and an output end of the transmission line conductor, and a second conductor formed with the first conductor. 1 substrate, a coverlay covering the transmission line conductor, a first shield having a second conductor formed on the second substrate, and a second shield having a third conductor formed on the third substrate, The coverlay is thermocompression bonded to the first substrate, the first substrate is thermocompression bonded to the second substrate, and the third substrate is thermocompression bonded to the coverlay, The second conductor and the third conductor are disposed so as to surround the transmission line conductor and are ultrasonically bonded to each other, and the transmission line conductor is formed at a first spacing. The method includes folding an end of the second conductor over the ground conductor, an anvil abutting the end, and a horn having a frustum disposed at a second spacing on the anvil. The end portion and the ground conductor are ultrasonically welded by the anvil and the horn by protruding from opposite directions and contacting the ground conductor.

According to this configuration, the end of the second conductor and the ground conductor can be reliably ultrasonically bonded at an accurate position. Also, by holding down the overlapping portion of the second conductor and the ground conductor with an anvil, it is possible to prevent the conductor from being pulled during ultrasonic bonding. Further, it is possible to prevent the thermoplastic resin from being extruded more than necessary during ultrasonic bonding, and to alleviate thermal strain when the thermoplastic resin thermally shrinks after ultrasonic bonding. Therefore, it is possible to manufacture a transmission line having shielding performance, a thin structure corresponding to space saving, and a structure with little transmission loss corresponding to high-speed transmission.

INDUSTRIAL APPLICABILITY According to the transmission line of the present invention, it is possible to realize a transmission line that has shielding performance necessary for use in electronic equipment, is thin enough to save space, and has a structure with little transmission loss that is compatible with high-speed transmission. .

FIG. 1 is a schematic perspective view showing an example of a transmission line according to this embodiment. 2 is a plan view of the transmission line shown in FIG. 1. FIG. FIG. 3 is a cross-sectional view of the transmission line shown in FIG. 2 taken along line III-III. FIG. 4 is a cross-sectional view of the transmission line shown in FIG. 2 taken along line IV-IV. 5A is a schematic cross-sectional view showing an ultrasonic bonding structure in the transmission line manufacturing method of the present embodiment, FIG. 5B is a schematic perspective view showing an example of the first tip portion in FIG. 5A, and FIG. FIG. 5B is a schematic perspective view showing an example of the second tip in FIG. 5A; 6 is a bottom view of the transmission line shown in FIG. 1. FIG. FIG. 7 is a flow chart showing the manufacturing procedure of the transmission line of this embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As an example, the transmission line 20 of the present embodiment has two transmission line conductors 32 formed with a first spacing P1, and one end and the other end are symmetrical. FIG. 1 is a schematic perspective view showing an example of the transmission line 20, and an area P4 surrounded by a broken line shows an enlarged view of the end of the transmission line 20. As shown in FIG. FIG. 2 is a schematic plan view showing an example of the transmission line 20, and an area P5 surrounded by a broken line shows an enlarged view of the end of the transmission line 20. As shown in FIG. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 4 is a sectional view taken along line IV-IV of FIG. FIG. 6 is a schematic bottom view showing an example of the transmission line 20, and an area P6 surrounded by a broken line shows an enlarged view of the end of the transmission line 20. As shown in FIG. In addition, in all drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and repeated description thereof may be omitted.

As shown in FIGS. 1 to 6, the transmission line 20 is made of a flexible multilayer wiring board, and the transmission line 20 has a first conductor 31 made up of a transmission line conductor 32 and a ground conductor 33, and a first conductor 31. a coverlay 35 covering the transmission line conductor 32; a first shield 40 having a second conductor 41 formed on the second substrate 42; a second shield 45 formed on a third substrate 47, the coverlay 35 being thermocompression bonded to the first substrate 34, the first substrate 34 being thermocompression bonded to the second substrate 42; The third base material 47 is thermocompression bonded to the coverlay 35, the second conductor 41 and the third conductor 46 are arranged so as to surround the transmission line conductor 32 and are ultrasonically bonded to each other, and the second conductor 41 is The folded end portion 41a overlaps the ground conductor 33 and is ultrasonically bonded. As an example, a connector is mounted on the input end of the transmission line conductor 32 and connected to the control circuit, a connector is mounted on the output end of the transmission line conductor 32 and connected to the antenna structure, and the control circuit and the antenna structure are connected. and are signal connected.

As an example, the first base material 34 and the coverlay 35 are made of thermoplastic fluororesin. The second conductor 41 has a through hole 41b formed at a second interval P2 at a position overlapping the ground conductor 33 in bottom view. As an example, the second base material 42 and the third base material 47 are made of thermoplastic polyimide resin.

As an example, the apparatus for manufacturing the transmission line 20 includes, in order from the upstream side, a first conductor forming machine, an unnecessary area removing machine, a first joining machine, a thermocompression bonding machine, a second joining machine, an inspection machine, and a split extraction machine. and has a controller to control them. This manufacturing apparatus may apply the techniques of Patent Documents 2 and 3 described above.

Next, a method for manufacturing the transmission line 20 according to the present invention will be described below.

FIG. 7 is a flow chart showing the manufacturing procedure of the transmission line 20 of this embodiment. As an example, the transmission line 20 is manufactured in the order of a first conductor forming step S1, an unnecessary region removing step S2, a first bonding step S3, a thermocompression bonding step S4, a second bonding step S5, an inspection step S6, and a division step S7.

As an example, the first conductor 31, the second conductor 41 and the third conductor 46 are made of copper or a copper alloy. In the first conductor forming step S1, the double-sided copper-clad substrate is etched by a subtractive method to form the transmission line conductor 32 and the ground conductor 33 on the first main surface of the first substrate 34, thereby forming the first substrate. The conductor is removed from the second major surface of material 34 to form base 30 . As a result, warpage can be prevented and the flat base 30 can be obtained. As a method other than the above, the transmission line conductor 32 and the ground conductor 33 can be formed to form the base 30 by pattern plating the first main surface of the first substrate 34 by an additive method.

The base 30 has transmission line conductors 32 formed at a first spacing P1. The first conductor 31 is composed of a transmission line conductor 32 formed in a straight line and a ground conductor 33 adjacent to an input end and an output end of the transmission line conductor 32, respectively. Base 30 has a waste area between transmission line conductors 32 .

As an example, the first substrate 34 and the coverlay 35 may be made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene (FEP), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene-hexafluoropropylene (FEP), It is selected from fluoroethylene-ethylene copolymer (ETFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF) and other known thermoplastic fluororesins. As an example, the second base material 42 and the third base material 47 are made of thermoplastic polyimide resin.

In the unnecessary area removing step S2, in a state where the base 30 and the coverlay 35 are superimposed, an unnecessary area removing machine is used to punch out unnecessary areas between the transmission line conductors 32 to form a rectangular shape. Form a through hole. The first joining step S3 uses the first joining machine to ultrasonically join the second conductor 41 to the third conductor 46 at the portion of the work from which the unnecessary region has been removed.

In the thermocompression bonding step S4, the workpieces are thermocompression bonded together by a roll press using a thermocompression bonding machine. Thereby, the coverlay 35 is thermocompression bonded to the first base material 34 , the first base material 34 is thermocompression bonded to the second base material 42 , and the third base material 47 is thermocompression bonded to the coverlay 35 .

In the second bonding step S5, the projecting portion of the first shield 40 arranged on the bottom surface of the work is folded back to the top surface of the work, the folded end portion 41a of the second conductor 41 is overlapped with the ground conductor 33, and the second The end 41a of the second conductor 41 is ultrasonically bonded to the ground conductor 33 using a bonding machine. As shown in FIGS. 5A to 5C, when ultrasonically bonding the end portion 41a of the second conductor 41 to the ground conductor 33, the anvil 61 abuts the end portion 41a from above, and the ground conductor 33 faces the anvil 61. Using a horn 62 having frustums arranged at a second interval P2, the horn 62 is pushed from the direction facing the anvil 61 and brought into contact with the ground conductor 33, and the anvil 61 and the horn 62 are brought into contact with each other. , the end portion 41a and the ground conductor 33 are ultrasonically bonded.

As an example, on the surface of the anvil 61 that contacts the end portion 41a, truncated square pyramids with tips of 0.1 mm×0.1 mm and oblique projection angles of 45 degrees are arranged in a matrix at a pitch of 0.28 mm. As an example, the horn 62 has a truncated cone with a diameter of 0.1 mm at its tip, and is arranged in a line with the second interval P2 of 1.12 mm.

The inspection step S6 inspects that the transmission line conductor 32 is not disconnected and that the continuity level is within the normal range by contacting the contact pin of the inspection machine to the transmission line conductor 32 and energizing it. In the dividing step S7, the work is punched out along a predetermined cut line by the punching blade of the split take-out machine.

Next, Example 1 and Example 2 will be described below.

[Example 1]
In the transmission line 20 of Example 1, the first base material 34 and the coverlay 35 are made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The transmission line 20 has a total length of 192 mm, a width of 8.8 mm, a thickness of 0.35 mm, and a first interval P1 of 4 mm. The first conductor 31, the second conductor 41 and the third conductor 46 are made of copper and have a thickness of 12 μm. The through hole 41b is formed in a conical shape in the thickness direction and penetrates the first base material 34 and the coverlay 35 .

[Example 2]
In the transmission line 20 of Example 2, the first base material 34 and the coverlay 35 are made of liquid crystal polymer (LCP). Other than that, the configuration is the same as that of the first embodiment described above.

For each sample, a network analyzer (N5247A manufactured by Keysight Technologies) was used to measure the transmission loss at a frequency of 3 GHz and the transmission loss at a frequency of 6 GHz. The evaluation results are shown in Table 1 below.

As shown in Table 1, it was confirmed that Example 1 was greatly improved in transmission loss compared to Example 2. This indicates that the transmission loss can be improved by using a material having a lower relative permittivity in a high frequency band as the thermoplastic resin forming the first base material 34 and the coverlay 35 . It also shows that transmission loss can be improved by using a material with a lower dielectric loss tangent in a high frequency band. As a reference example, it was confirmed that the transmission loss was improved by 15% when compared with a coaxial cable combining the same materials.

Although PFA or LCP was used as the first base material 34 and the coverlay 35 in the above-described embodiment, the present invention is not limited to this example, and known thermoplastic resins can be applied. Also, in the above-described embodiment, the flexible substrate has a four-layer structure, but the present invention is not limited to this example. A multi-layer structure of five or more layers can also be used depending on the application. Although the above embodiment has been described with a configuration in which there are two transmission line conductors 32, the present invention is not limited to this example. In some cases, the transmission line conductors 32 are configured to have three or more. Alternatively, a single transmission line conductor 32 may be used. The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention.

20 transmission line 30 base 31 first conductor 32 transmission line conductor 33 ground conductor 34 first substrate 35 coverlay 40 first shield 41 second conductor 41a end 41b through hole 42 second substrate 45 second shield 46 Third conductor 47 Third substrate 61 Anvil 62 Horn P1 First spacing P2 Second spacing

Claims (5)

A first conductor consisting of a transmission line conductor and a pair of ground conductors respectively adjacent to an input end and an output end of the transmission line conductor; a first substrate on which the first conductor is formed; and covering the transmission line conductor. a coverlay, a first shield having a second conductor formed on a second substrate, and a second shield having a third conductor formed on a third substrate, the coverlay applying heat to the first substrate; wherein the first substrate is thermocompression bonded to the second substrate, the third substrate is thermocompression bonded to the coverlay, and the second conductor and the third conductor are bonded to the A transmission line, wherein a transmission line conductor is disposed so as to surround the transmission line conductor and ultrasonically bonded to each other, and a folded end of the second conductor overlaps the ground conductor and is ultrasonically bonded. 2. The transmission line conductor is formed at a first interval, and the second conductor is formed with through holes at a second interval at a position overlapping the ground conductor in a bottom view. The transmission line described in . 3. The transmission line according to claim 1, wherein the first base material and the coverlay are made of fluororesin. A first conductor consisting of a transmission line conductor and a pair of ground conductors respectively adjacent to an input end and an output end of the transmission line conductor; a first substrate on which the first conductor is formed; and covering the transmission line conductor. a coverlay, a first shield having a second conductor formed on a second substrate, and a second shield having a third conductor formed on a third substrate, the coverlay applying heat to the first substrate; wherein the first substrate is thermocompression bonded to the second substrate, the third substrate is thermocompression bonded to the coverlay, and the second conductor and the third conductor are bonded to the A manufacturing method for manufacturing a transmission line arranged to surround a transmission line conductor and ultrasonically bonded to each other, the transmission line conductor being formed at a first spacing, the end of the second conductor part is folded back and overlapped with the ground conductor, an anvil is brought into contact with the end, and a horn having frustums arranged at a second interval is pushed from a direction facing the anvil to come into contact with the ground conductor. and ultrasonically bonding the end portion and the ground conductor by the anvil and the horn. 5. The method of manufacturing a transmission line according to claim 4, wherein the first base material and the coverlay are made of fluororesin.

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