JP2016129949A - Flexible laminate and method for manufacturing flexible laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a dimensional change rate of a flexible laminate.SOLUTION: A method for manufacturing a flexible laminate is provided, which includes a thermal compression-bonding step of continuously supplying an insulation film 11 made of a liquid crystal polymer and a metal foil 12 into between a pair of endless belts 23, 24 and thermally compression-bonding the film and the foil to form a flexible laminate 10. In the compression-bonding step, the flexible laminate 10 is heated in such a manner that a maximum temperature (first temperature T1) of the flexible laminate 10 is within a range from a temperature that is lower by 45°C than the melting point of the liquid crystal polymer constituting the insulation film 11 to a temperature that is lower by 5°C than the melting point; and the flexible laminate 10 is gradually cooled in such a manner that an exit temperature (second temperature T2) of the flexible laminate 10 carried out from the endless belts 23, 24 is within a range from a temperature lower by 235°C than the melting point of the liquid crystal polymer constituting the insulation film 11 to a temperature lower by 100°C than the melting point.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flexible laminate in which an insulating layer made of a liquid crystal polymer and a metal layer are bonded, and a method for manufacturing the flexible laminate.

  The flexible laminated board with which the insulating layer and the metal layer were adhere | attached is used as a material for manufacturing a flexible printed wiring board, for example. In recent years, flexible laminates using a liquid crystal polymer, which is a low dielectric material, as an insulating layer have attracted attention because of the demand for higher frequencies for flexible printed wiring boards.

  For example, in Patent Document 1, by using a double belt press device, a metal foil is overlapped on both surfaces of an insulating film made of a liquid crystal polymer, and the insulating film and the metal foil are thermocompression bonded by hot pressing. A technique for manufacturing a flexible laminate is disclosed. In addition, by setting the heating temperature at the time of hot pressing to a range of not less than the melting point of the liquid crystal polymer constituting the insulating film and not more than 20 degrees higher than the melting point, the insulating layer and the metal The point that generation | occurrence | production of a dimensional distortion etc. can be reduced, maintaining the peel strength between foil is disclosed.

JP 2010-221694 A

  By the way, in recent years, a flexible laminate having a small dimensional change rate has been demanded with the progress of high-density mounting technology for flexible printed wiring boards. Specifically, a flexible laminate having a small dimensional change rate before and after the formation of a conductor circuit and before and after a heating step in reflow soldering for mounting various elements is required.

  This invention is made | formed in view of such a situation, The objective is to provide the flexible laminated board with a small dimensional change rate.

  A flexible laminate for achieving the above object is a flexible laminate comprising an insulating layer made of a liquid crystal polymer and a metal layer formed on one or both sides of the insulating layer, the liquid crystal polymer having a melting point Is a liquid crystal polymer having a temperature exceeding 250 ° C., and in the dimensional stability test specified in JIS C 6471, the dimensional change rate when the heating temperature is 250 ° C. is within a range of ± 0.05%, and the insulating layer The standard deviation of the thickness in the width direction is 1.2 μm or less.

  In order to achieve the above object, a method for manufacturing a flexible laminate includes: continuously supplying an insulating film made of a liquid crystal polymer and a metal foil between a pair of endless belts; and insulating film and metal foil between the endless belts. In the thermocompression bonding step, the maximum temperature of the flexible laminate is 45 ° C. or more lower than the melting point of the liquid crystal polymer constituting the insulating film. The liquid crystal polymer that heats the flexible laminate so that the temperature is 5 ° C. or lower than the same melting point, and the outlet temperature of the flexible laminate when being unloaded from the endless belt constitutes the insulating film So that the temperature is within a range of 235 ° C. lower than the melting point of the glass and 100 ° C. lower than the same melting point. Slowly cooling the reluctant laminate.

  In the method for producing a flexible laminate, the insulating film is a liquid crystal polymer having 6-hydroxy-2-naphthoic acid and parahydroxybenzoic acid as structural units, the melting point of which is higher than 250 ° C. It is preferable to use an insulating film.

  In the method for producing a flexible laminate, it is preferable to use at least one metal foil selected from copper foil, aluminum foil, stainless steel foil, and foil made of an alloy of copper and aluminum as the metal foil.

  According to the present invention, a flexible laminate having a small dimensional change rate can be obtained.

The schematic diagram which shows schematic structure of a thermocompression bonding process. The schematic diagram which shows schematic structure of the thermocompression bonding process of the example of a change.

Hereinafter, an embodiment embodying the method for producing a flexible laminate of the present invention will be described in detail with reference to FIG.
The manufacturing method of the flexible laminated board 10 of this embodiment has the thermocompression bonding process which heat-presses the metal foil 12 continuously on both surfaces of the insulating film 11, and the flexible laminated board 10 is manufactured through this thermocompression bonding process.

First, the insulating film 11 and the metal foil 12 used for manufacturing the flexible laminate 10 will be described.
The insulating film 11 constitutes an insulating layer in the flexible laminate 10. As the insulating film 11, an insulating film 11 formed of a liquid crystal polymer having a melting point exceeding 250 ° C. is used. Examples of the liquid crystal polymer include a liquid crystal polymer having ethylene terephthalate and parahydroxybenzoic acid as structural units, a liquid crystal polymer having phenol, phthalic acid and parahydroxybenzoic acid as structural units, 6-hydroxy-2-naphthoic acid and parahydroxy Examples thereof include liquid crystal polymers having benzoic acid as a structural unit.

  Although the thickness of the insulating film 11 is not specifically limited, For example, it is preferable that it is the range of 6-300 micrometers, it is more preferable that it is the range of 12-150 micrometers, and it is the range of 25-100 micrometers. Is more preferable.

  The metal foil 12 constitutes a metal layer in the flexible laminate 10. As the metal foil 12, for example, a copper foil, an aluminum foil, a stainless steel foil, and a metal foil such as a foil made of an alloy of copper and aluminum can be used. In particular, from a rolled copper foil, an electrolytic copper foil, and an aluminum foil. It is preferable to use at least one selected.

  The surface roughness of the metal foil 12 is not particularly limited. For example, the ten-point average roughness (Rz) is preferably in the range of 0.5 to 10 μm, and in the range of 0.5 to 7 μm. It is more preferable that The thickness of the metal foil 12 is not particularly limited, but is preferably in the range of 1.5 to 150 μm, more preferably in the range of 2 to 70 μm, and 9 to 35 μm. More preferably, it is in the range.

Next, the thermocompression bonding process in the manufacturing method of this embodiment will be described.
As shown in FIG. 1, the thermocompression bonding process was carried out of the double belt press device 20, the feeding unit 30 that supplies the insulating film 11 and the metal foil 12 to the double belt press device 20, and the double belt press device 20. It implements with the manufacturing line provided with the winding part 40 which winds up the flexible laminated board 10. FIG.

  The double belt press device 20 is provided in parallel with a pair of upper drums 21 arranged in parallel with a predetermined interval in the conveying direction and with a predetermined interval in the conveying direction on the lower side of each upper drum 21. And a pair of lower drums 22. An endless belt 23 is bridged between the pair of upper drums 21. The endless belt 23 is configured to rotate when the pair of upper drums 21 rotate. Similarly, an endless belt 24 is bridged between the pair of lower drums 22. The endless belt 24 is configured to rotate when the pair of lower drums 22 rotate. Note that the endless belts 23 and 24 are made of a metal material such as stainless steel, copper alloy, aluminum alloy, or the like.

  Inside each endless belt 23, 24, a hot-pressing device 25 is provided that is positioned above and below the endless belt 23, 24. The hot-pressing device 25 is a device for applying a predetermined pressure to a portion of the endless belts 23, 24 located between the hot-pressing devices 25 and heating the same portion. And the heat press apparatus 25 is comprised so that heating temperature can be adjusted for every predetermined range in a conveyance direction. For example, the heat and pressure apparatus 25 shown in FIG. 1 can individually adjust the heating temperature in each of the four portions 25A to 25D provided along the transport direction.

  In the feeding portion 30, an insulating film roll 31 in which a long insulating film 11 is wound in a roll shape, and two sets of metal foil rolls in which a long metal foil 12 is wound in a roll shape 32 is provided.

  In the thermocompression bonding process, first, the double belt press device 20 while the metal foil 12 fed out from the metal foil roll 32 is superposed on both surfaces of the insulating film 11 fed out from the insulating film roll 31 of the feeding unit 30. Continuously supplied. The insulating film 11 and the metal foil 12 supplied to the double belt press device 20 are conveyed to the downstream side while being sandwiched between the endless belts 23 and 24 as the endless belts 23 and 24 are rotated.

  When passing between the endless belts 23, 24, a predetermined surface pressure is applied to the insulating film 11 and the metal foil 12 via the endless belts 23, 24 by the hot press device 25. At the same time, the insulating film 11 and the metal foil 12 are heated by the hot press device 25 via the endless belts 23 and 24. Thereby, the insulating film 11 is softened, the insulating film 11 and the metal foil 12 are thermocompression-bonded, and the flexible laminated board 10 which has a metal layer on both surfaces of an insulating layer is formed. And the flexible laminated board 10 carried out from the double belt press apparatus 20 is collect | recovered by being wound in roll shape in the winding part 40. FIG.

  Here, the heating with respect to the insulating film 11 and the metal foil 12 in a thermocompression bonding process is performed as follows. That is, in the upstream region (heating zone) between the endless belts 23 and 24, the insulating film 11 and the metal foil 12 are heated so as to reach the first temperature T1. And in the area | region (slow cooling zone) of the same downstream side, the flexible laminated board 10 is 1st temperature, weakening the heating with respect to the insulating film 11 and the metal foil 12, and cooling the insulating film 11 and the metal foil 12 gradually. It heats so that it may carry out from the double belt press apparatus 20 at 2nd temperature T2 lower than T1. In other words, the flexible laminated board 10 (the insulating film 11 and the metal foil 12) when passing between the endless belts 23 and 24 is heated so as to have the first temperature T1, and is transported from the endless belts 23 and 24. The outlet temperature of the flexible laminate 10 is heated to the second temperature T2. In addition, in the boundary part of said heating zone and a slow cooling zone, the aspect of a heating is changed, maintaining the state where the predetermined surface pressure was applied to the flexible laminated board 10 (the insulating film 11 and the metal foil 12). To do.

  The first temperature T1 is in a range of “mp−45 ° C. ≦ T1 ≦ mp−5 ° C.” when the melting point of the liquid crystal polymer forming the insulating film 11 is mp. That is, the temperature is in the range of 45 ° C. lower than the melting point of the liquid crystal polymer and 5 ° C. lower than the melting point. For example, when the melting point of the liquid crystal polymer forming the insulating film 11 is 335 ° C., the first temperature T1 is in the range of “290 ° C. ≦ T1 ≦ 330 ° C.”. “Mp−45 ° C.” which is the lower limit of the first temperature T1 is the minimum temperature necessary to sufficiently bond the insulating film 11 and the metal foil 12 together.

  In addition, “mp−5 ° C.” that is the upper limit of the first temperature T1 is the maximum temperature at which the melting of the liquid crystal polymer that forms the insulating film 11 is suppressed. Once the liquid crystal polymer melts, the molecular orientation is disturbed by the flow of the liquid crystal polymer, and the flexible laminate 10 is formed with the stress remaining. As a result, when the flexible laminate 10 is heat-treated again, a large dimensional change occurs. By setting the upper limit of the first temperature T1 to “mp-5 ° C.” and suppressing the melting and flow of the liquid crystal polymer, such problems are less likely to occur, and the dimensional change rate of the flexible laminate 10 before and after the heat treatment is reduced. Can be made.

  The second temperature T2 is in the range of “mp−235 ° C. ≦ T2 ≦ mp−100 ° C.” when the melting point of the liquid crystal polymer forming the insulating film 11 is mp. That is, it is in the range of 235 ° C. lower than the melting point of the liquid crystal polymer and 100 ° C. lower than the melting point. For example, when the melting point of the liquid crystal polymer forming the insulating film 11 is 335 ° C., the second temperature T2 is in the range of “100 ° C. ≦ T2 ≦ 235 ° C.”. By performing the slow cooling so that the second temperature T2 falls within the above range, it is possible to suppress the influence of the change in orientation due to the flow of the liquid crystal polymer caused by reaching the first temperature T1. As a result, the dimensional change rate of the flexible laminate 10 before and after performing the heat treatment can be reduced.

  In addition, 1st temperature T1 can be confirmed by measuring the temperature of the flexible laminated board 10 at the time of passing the position in which the heating temperature switches to the reduction | decrease side in the hot-pressure apparatus 25. FIG. For example, in the heat and pressure apparatus 25 shown in FIG. 1, the portions 25A to 25B are heated at a high temperature to be heated to the first temperature T1, and the portions 25C to 25D are gradually cooled to the second temperature T2. When heated at a low temperature, the first temperature T1 is confirmed by measuring the temperature of the flexible laminate 10 when passing through a position corresponding to the boundary between the region 25B and the region 25C. The second temperature T2 can be confirmed by measuring the temperature of the flexible laminate 10 immediately after being unloaded from the endless belts 23, 24.

  Furthermore, the difference (T1−T2) between the first temperature T1 and the second temperature T2 is preferably in the range of 55 to 230 ° C. The ratio (T1 / T2) between the first temperature T1 and the second temperature T2 is preferably in the range of 1.2 to 3.3.

  In addition, the surface pressure applied to the insulating film 11 and the metal foil 12 when passing between the endless belts 23 and 24 is preferably in the range of 0.5 to 6.0 MPa, for example, 1.5 to 5 More preferably, it is in the range of 0.0 MPa.

  The flexible laminated board 10 manufactured through the said thermocompression bonding process turns into a flexible laminated board with a small dimensional change rate. For example, in the dimensional stability test specified in JIS C 6471, the dimensional change rate when the heating temperature is 250 ° C. is within a range of ± 0.05%. Moreover, the flexible laminated board 10 becomes a flexible laminated board with small thickness nonuniformity. For example, the standard deviation of the thickness in the width direction of the insulating layer is 1.2 μm or less.

  The flexible laminate 10 obtained by the manufacturing method of the present embodiment is used for a flexible printed circuit board, and is also used for a tape used for a mounting method such as a TAB (Tape Automated Bonding) method or a COF (Chip on Film) method. Can do. Examples of products equipped with the flexible laminate 10 include electronic devices such as cameras, personal computers, liquid crystal displays, printers, and portable devices.

Next, the effect of this embodiment will be described.
(1) The manufacturing method of a flexible laminated board supplies the insulating film 11 and metal foil 12 which consist of a liquid crystal polymer continuously between a pair of endless belts 23 and 24, and the insulating film 11 is between the endless belts 23 and 24. And a metal foil 12 are thermocompression-bonded to form a flexible laminate 10.

  In the thermocompression bonding step, the maximum temperature (first temperature T1) of the flexible laminated plate 10 is in a range not lower than 45 ° C. below the melting point of the liquid crystal polymer constituting the insulating film 11 and not higher than 5 ° C. below the melting point. The outlet temperature (second temperature T2) of the flexible laminated board 10 when the flexible laminated board 10 is heated and carried out from the endless belts 23 and 24 is 235 ° C. lower than the melting point of the liquid crystal polymer constituting the insulating film 11. As described above, the flexible laminate 10 is gradually cooled so as to be in a range of 100 ° C. or lower than the same melting point.

  According to the said structure, the dimensional change rate of the flexible laminated board 10, especially the dimensional change rate before and behind 250 degreeC heat processing can be reduced. When the flexible laminate 10 is used as a flexible printed board, the flexible laminate 10 is exposed to a high temperature of about 250 ° C. when forming a conductor circuit or reflow soldering for mounting various elements. Suppressing the dimensional change of the flexible laminate 10 at this time is important from the viewpoint of high-density mounting. Therefore, the flexible laminated board 10 in which the dimensional change rate before and after the heat treatment at 250 ° C. is reduced is useful as a material for a flexible printed board for high-density mounting.

In addition, this embodiment can also be changed and embodied as follows.
In the said embodiment, although the metal foil 12 was thermocompression bonded to both surfaces of the insulating film 11, the flexible laminated board which carries out the thermocompression bonding of the metal foil 12 only to the single side | surface of the insulating film 11, and has a metal layer on the single side | surface of an insulating layer. 10 may be formed.

  For example, as shown in FIG. 2, a release film roll 33 in which a long release film 13 is wound in a roll shape is provided for the feeding portion 30. And in the thermocompression bonding process, the metal foil 12 fed out from the metal foil roll 32 is overlapped on one surface of the insulating film 11 fed out from the insulating film roll 31 of the feeding part 30 and the opposite side of the insulating film 11 is overlapped. These are continuously supplied to the double belt press device 20 while the release film 13 fed from the release film roll 33 is stacked on one side. The flexible laminated board 10 carried out from the double belt press apparatus 20 is collected by winding it in a roll shape at the winding section 40 with the release film 13 being overlaid. The heating conditions and pressure conditions in this thermocompression bonding step are the same as in the above embodiment.

  The release film 13 is a film for suppressing transfer of the softened insulating film 11 to the double belt press apparatus 20 in the thermocompression bonding step. As the release film 13, a known release film used for manufacturing a flexible laminate can be used. In particular, a flexible material having high heat resistance and good releasability, for example, a release film made of at least one selected from non-thermocompression-resistant heat-resistant aromatic polyimide, fluororesin, and silicone resin is used. preferable.

  Note that the release film 13 is appropriately peeled off when the flexible laminate 10 is used. Further, a separate collecting roll for collecting the release film 13 is provided in the winding unit 40, and the release film 13 is peeled off from the flexible laminate 10 at the timing when the release film 13 is carried out from the double belt press device 20, and the flexible lamination is performed. The plate 10 and the release film 13 may be collected separately.

Next, the above embodiment will be described more specifically with reference to examples and comparative examples.
(Examples 1-13, Comparative Examples 1-12)
Using a double belt press device, various heating conditions in the thermocompression bonding process were set, a flexible laminate having metal layers on both sides or one side of the insulating layer was manufactured, and the quality of the obtained flexible laminate was evaluated. . The heating conditions in the thermocompression bonding process are as shown in Tables 1 and 2. That is, in each example, the first temperature T1 is in the range of “mp−45 ° C. <T1 <mp−5 ° C.” (290 ° C. <T1 <330 ° C.), and the second temperature T2 is “mp−235 ° C.” <T2 <mp-100 ° C. ”(100 ° C. <T2 <235 ° C.). In each comparative example, one of the first temperature T1 and the second temperature T2 is out of the above range.

Moreover, manufacturing conditions other than heating conditions, such as material, are as follows.
Metal foil: Rolled copper foil (manufactured by JX Nippon Mining & Metals, BHYX-92-HA).
Insulating film: LCP film (Kuraray Co., Ltd., Bexter CTZ, melting point 335 ° C.).

Release film: Polyimide film (Ube Industries, Upilex S, thickness 25 μm). The release film was peeled off from the flexible laminate after the thermocompression bonding step.
Pressure: 4.0 MPa
In addition, the thickness of the used metal foil and insulating film is as showing in Table 1 and Table 2.

(Evaluation of dimensional change rate)
Based on the dimensional stability test prescribed | regulated to JISC6471, the dimensional change rate of the flexible laminated board when the heating temperature was changed into 150 degreeC and 250 degreeC was measured. The results are shown in Tables 1 and 2.

(Evaluation of thickness unevenness)
A sample having a width of 50 mm × 520 mm was taken from the flexible laminates of the examples and comparative examples, and the metal layer was removed from the sample by etching. And about the remaining insulating layer, the thickness in 52 points | pieces was measured at 10 mm intervals in the width direction using the dot type thickness meter, and the standard deviation was computed. The results are shown in Tables 1 and 2.

(Evaluation of peel strength)
Using the test method defined in JIS C 6471, the peel strength (peel strength) of the metal layer was measured for the flexible laminates of Examples and Comparative Examples. The results are shown in Tables 1 and 2.

First, in the comparative examples 1, 3, 5, 7, and 9 in which the second temperature T2 is lower than “mp-235 ° C.” (100 ° C.), as shown in the column of continuous operation in Table 2, At the stage where a flexible laminate having a predetermined length was manufactured, a problem occurred in the rotation of the belt of the double belt press device, and the double belt press device could not be operated continuously. Therefore, these flexible laminates were judged to be extremely low in mass productivity, and the evaluation of the rate of dimensional change, the evaluation of thickness unevenness, and the evaluation of peel strength were not performed. On the other hand, such problems did not occur in other examples and comparative examples in which the second temperature T2 was set to a temperature of “mp-235 ° C.” (100 ° C.) or higher.

  From the comparison between Examples 2, 4, 6, 8, and 10 and Comparative Examples 2, 4, 6, 8, and 10, the second temperature T2 is set to a temperature higher than “mp-100 ° C.” (235 ° C.). The results showed that the dimensional change rate in the test at 150 ° C. and 250 ° C. increased more than twice.

  From the comparison between Example 1 and Comparative Examples 11 and 12, when the first temperature T1 was set to a temperature higher than “mp-5 ° C.” (330 ° C.), the dimensional change in the test at 150 ° C. and 250 ° C. The result was that the rate increased more than twice.

As shown in Table 1, in each example, the thickness unevenness showed a small value of 1.2 μm or less, and the peel strength showed a high value of 0.6 N / m or more.
From these results, when the first temperature T1 and the second temperature T2 are within the above ranges, the dimensional change rate before and after heating at 250 ° C. can be reduced while ensuring quality such as thickness unevenness and peel strength. It could be confirmed. It was also confirmed that there was no problem in terms of mass productivity of the flexible laminate. These effects were the same in the case where the thickness of the insulating film was changed (Examples 11 and 12) and in the case where a flexible laminate having a metal layer on one side (Example 13) was used. Furthermore, although detailed data is omitted, when an electrolytic copper foil having a thickness of 12 μm (3EC-VLP, manufactured by Mitsui Mining & Smelting Co., Ltd.) is used as the metal foil, another LCP film (Primatec Co., Ltd.) is used as the insulating film. Similar results were obtained when using BIAC-BC manufactured by company, melting point 315 ° C., thickness 50 μm).

  DESCRIPTION OF SYMBOLS 10 ... Flexible laminated board, 11 ... Insulating film, 12 ... Metal foil, 13 ... Release film, 20 ... Double belt press apparatus, 21 ... Upper drum, 22 ... Lower drum, 23, 24 ... Endless belt, 25 ... Heat Pressure device, 30 ... feeding portion, 31 ... insulating film roll, 32 ... metal foil roll 32, 33 ... release film roll, 40 ... winding portion.

Claims (4)

A flexible laminate comprising an insulating layer made of a liquid crystal polymer and a metal layer formed on one or both sides of the insulating layer,
The liquid crystal polymer is a liquid crystal polymer having a melting point exceeding 250 ° C.,
In the dimensional stability test defined in JIS C 6471, the dimensional change rate when the heating temperature is 250 ° C. is within a range of ± 0.05%.
A flexible laminate having a standard deviation in thickness in the width direction of the insulating layer of 1.2 μm or less. A method for producing a flexible laminate,
A thermocompression bonding step of continuously supplying an insulating film made of a liquid crystal polymer and a metal foil between a pair of endless belts, and thermally bonding the insulating film and the metal foil between the endless belts. Have
In the thermocompression bonding step,
While heating the flexible laminate so that the maximum temperature of the flexible laminate is 45 ° C. lower than the melting point of the liquid crystal polymer constituting the insulating film, the temperature is 5 ° C. lower than the melting point,
The outlet temperature of the flexible laminate when unloaded from the endless belt is in a range of 235 ° C. lower than the melting point of the liquid crystal polymer constituting the insulating film and not more than 100 ° C. lower than the melting point. A method for producing a flexible laminate, comprising cooling the flexible laminate slowly.   The insulating film, which is a liquid crystal polymer having 6-hydroxy-2-naphthoic acid and parahydroxybenzoic acid as structural units and having a melting point exceeding 250 ° C., as the insulating film. The manufacturing method of the flexible laminated board of 2.   The flexible metal according to claim 2 or 3, wherein at least one metal foil selected from a copper foil, an aluminum foil, a stainless steel foil, and a foil made of an alloy of copper and aluminum is used as the metal foil. A manufacturing method of a laminated board.