JP6518445B2 - FLEXIBLE LAMINATE AND METHOD FOR MANUFACTURING FLEXIBLE LAMINATE - Google Patents

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 of manufacturing the flexible laminate.

  A flexible laminate in which an insulating layer and a metal layer are bonded is used, for example, as a material for manufacturing a flexible printed wiring board. In recent years, a flexible laminate using a liquid crystal polymer, which is a low dielectric material, as an insulating layer has attracted attention from the demand for higher frequency of the flexible printed wiring board.

  For example, in Patent Document 1, metal foils are laminated on both sides of an insulation film made of liquid crystal polymer using a double belt press apparatus, and the insulation film and the metal foil are thermocompression-bonded by heat and pressure molding this. Techniques for making flexible laminates are disclosed. Further, by setting the heating temperature at the time of hot-press molding in the range not lower than the melting point of the liquid crystal polymer constituting the insulating film and not higher than the melting point by 20 degrees, an insulating layer and metal are manufactured for the manufactured flexible laminate. It is disclosed that the occurrence of dimensional distortion and the like can be reduced while maintaining the peel strength with the foil.

Unexamined-Japanese-Patent No. 2010-221694

  By the way, in recent years, with the advance of the technology of high density mounting on a flexible printed wiring board, a flexible laminated board with a small dimensional change rate is required. Specifically, flexible laminates 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 are required.

  This invention is made 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 liquid crystal polymer and a metal layer formed on one side or both sides of the insulating layer, and the liquid crystal polymer has a melting point Is a liquid crystal polymer exceeding 250.degree. C., and in the dimensional stability test defined in JIS C 6471, the dimensional change when the heating temperature is 250.degree. C. is in the range of ± 0.05%, 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 of manufacturing a flexible laminate continuously supplies an insulating film made of a liquid crystal polymer and a metal foil between a pair of endless belts, and the insulating film and the metal foil are provided between the endless belts. And a thermocompression bonding step of forming a flexible laminate, wherein the maximum temperature of the flexible laminate is 45.degree. C. lower than the melting point of the liquid crystal polymer constituting the insulating film. And heating the flexible laminate to a temperature not more than 5 ° C. lower than the same melting point, and a liquid crystal polymer constituting the insulating film at the outlet temperature of the flexible laminate when carried out from the endless belt. Above the melting point of the melting point and a temperature not more than 100 ° C. of the 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, and the liquid crystal polymer has a melting point exceeding 250 ° C. It is preferable to use an insulating film.

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

  ADVANTAGE OF THE INVENTION According to this invention, the flexible laminated board with 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 a modification.

Hereinafter, one embodiment which materialized the manufacturing method of the flexible laminated board of the present invention is described in detail with reference to FIG.
The manufacturing method of the flexible laminated board 10 of this embodiment has a thermocompression-bonding process which thermocompression-bonds 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, the insulating film 11 formed of a liquid crystal polymer whose melting point exceeds 250 ° C. is used. Examples of liquid crystal polymers include liquid crystal polymers having ethylene terephthalate and parahydroxybenzoic acid as structural units, liquid crystal polymers having phenol and phthalic acid and parahydroxybenzoic acid as structural units, 6-hydroxy-2-naphthoic acid and parahydroxyl The liquid crystal polymer etc. which make benzoic acid a structural unit are mentioned.

  The thickness of the insulating film 11 is not particularly limited, but is preferably in the range of 6 to 300 μm, more preferably in the range of 12 to 150 μm, and more preferably in the range of 25 to 100 μm. Is more preferred.

  The metal foil 12 constitutes a metal layer in the flexible laminate 10. As the metal foil 12, for example, metal foil such as copper foil, aluminum foil, stainless steel foil, and foil made of an alloy of copper and aluminum can be used, and in particular, from rolled copper foil, electrolytic copper foil and 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 more preferably 9 to 35 μm. More preferably, it is in the range.

Next, the thermocompression-bonding process in the manufacturing method of this embodiment is described.
As shown in FIG. 1, in the thermocompression bonding step, the double belt press 20, the feeding unit 30 for supplying the insulating film 11 and the metal foil 12 to the double belt press 20, and the double belt press 20 were carried out. It carries out by the manufacturing line provided with the winding part 40 which winds up the flexible laminated board 10.

  The double belt press apparatus 20 is also provided in parallel at a predetermined interval in the transport direction on the lower side of each upper drum 21 and a pair of upper drums 21 disposed in parallel at a predetermined interval in the transport direction. A pair of lower drums 22 are provided. An endless belt 23 is stretched over the pair of upper drums 21. The endless belt 23 is configured to rotate by rotation of the pair of upper drums 21. Similarly, an endless belt 24 is stretched over the pair of lower drums 22. The endless belt 24 is configured to rotate by rotation of the pair of lower drums 22. The endless belts 23 and 24 are formed of, for example, a metal material such as stainless steel, copper alloy, or aluminum alloy.

  Inside the endless belts 23, 24, heat pressure devices 25 positioned above and below the endless belts 23, 24 are provided. The heat pressure device 25 is a device for applying a predetermined pressure to a portion of the endless belts 23 and 24 located between the heat pressure devices 25 and heating the same portion. And the heat-pressure apparatus 25 is comprised so that adjustment of heating temperature is possible for every predetermined range in a conveyance direction. For example, the heat-pressure apparatus 25 shown in FIG. 1 can adjust heating temperature separately in each of four site | part 25A-25D provided along the conveyance direction.

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

  In the thermocompression bonding step, first, the double-belt press device 20 while the metal foils 12 fed out from the metal foil rolls 32 are respectively superimposed on both surfaces of the insulation film 11 drawn out from the insulation film roll 31 of the feeding portion 30. Are supplied continuously. The insulating film 11 and the metal foil 12 supplied to the double belt press 20 are conveyed downstream while being sandwiched between the endless belts 23 and 24 by rotating the endless belts 23 and 24.

  When passing between the endless belts 23, 24, a predetermined surface pressure is applied to the insulating film 11 and the metal foil 12 by the heat and pressure device 25 via the endless belts 23, 24. At the same time, the insulating film 11 and the metal foil 12 are heated by the heat and pressure unit 25 through 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 laminate 10 having the metal layer on both sides of the 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 up in roll shape in the winding part 40. As shown in FIG.

  Here, heating of the insulating film 11 and the metal foil 12 in the thermocompression bonding step is performed as follows. That is, in the region (heating zone) on the upstream side between the endless belts 23 and 24, the insulating film 11 and the metal foil 12 are heated to reach the first temperature T1. And in the area | region (slow cooling zone) of the same downstream side, the heating with respect to the insulating film 11 and the metal foil 12 is weakened, and the flexible laminated board 10 is 1st temperature, annealing the insulating film 11 and the metal foil 12 gradually. It heats so that it may carry out of the double belt press apparatus 20 at 2nd temperature T2 lower than T1. In other words, the maximum temperature of the flexible laminate 10 (the insulating film 11 and the metal foil 12) when passing between the endless belts 23 and 24 is heated to the first temperature T1, and is carried out of the endless belts 23 and 24 It heats so that the exit temperature of the flexible laminated board 10 at the time of making may be 2nd temperature T2. In the boundary between the heating zone and the annealing zone, the mode of heating is changed while maintaining a state in which a predetermined surface pressure is applied to the flexible laminate 10 (the insulating film 11 and the metal foil 12). Do.

  1st temperature T1 is the range of "mp-45 degreeC <= T1 <= mp-5 degreeC" when melting | fusing point of the liquid crystal polymer which forms the insulating film 11 is set to mp. That is, the temperature is 45 ° C. or more lower than the melting point of the liquid crystal polymer and 5 ° C. or less 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.”. The lower limit “mp −45 ° C.” of the first temperature T1 is the minimum temperature required to sufficiently bond the insulating film 11 and the metal foil 12.

  Further, “mp −5 ° C.” which is the upper limit of the first temperature T1 is the maximum temperature at which the melting of the liquid crystal polymer forming the insulating film 11 is suppressed. Once the liquid crystal polymer is melted, the flow of the liquid crystal polymer disturbs the molecular orientation, 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 suppressing the melting and flow of the liquid crystal polymer by setting the upper limit of the first temperature T1 to “mp-5 ° C.”, such problems are less likely to occur, and the dimensional change of the flexible laminate 10 before and after heat treatment is reduced. It can be done.

  The second temperature T2 is in the range of “mp-235 ° C. ≦ T2 ≦ mp−100 ° C.” where the melting point of the liquid crystal polymer forming the insulating film 11 is mp. That is, it is in the range of not less than 235 ° C. than the melting point of the liquid crystal polymer and not more than 100 ° C. of 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 slow cooling so that the second temperature T2 falls within the above range, it is possible to suppress the influence of the change in alignment 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 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 where heating temperature switches to the fall side in the heat | fever pressure apparatus 25. FIG. For example, in the heat and pressure unit 25 shown in FIG. 1, the portions 25A to 25B are heated as the heating zone and heated to a high temperature to heat to the first temperature T1, and the portions 25C to 25D are reduced to the second temperature T2 as the slow cooling zone In the case of heating at a low temperature so as to cause the temperature, the first temperature T1 is confirmed by measuring the temperature of the flexible laminate 10 when passing through the position corresponding to the boundary between the portion 25B and the portion 25C. Moreover, 2nd temperature T2 can be confirmed by measuring the temperature of the flexible laminated board 10 immediately after being carried out from the endless belts 23 and 24. As shown in FIG.

  Furthermore, it is preferable that the difference (T1-T2) of 1st temperature T1 and 2nd temperature T2 is the range of 55-230 degreeC. The ratio (T1 / T2) of the first temperature T1 to the second temperature T2 is preferably in the range of 1.2 to 3.3.

  Moreover, when passing between the endless belts 23 and 24, the surface pressure applied to the insulating film 11 and the metal foil 12 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 defined in JIS C 6471, the dimensional change when the heating temperature is 250 ° C. is in the range of ± 0.05%. Moreover, the flexible laminated board 10 turns into a flexible laminated board with a 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 laminated board 10 obtained by the manufacturing method of the present embodiment is also used as a tape used for a flexible printed circuit board and used for a mounting method such as a TAB (Tape Automated Bonding) method or a COF (Chip on Film) method. Can. Moreover, as a product equipped with the flexible laminated board 10, electronic devices, such as a camera, a personal computer, a liquid crystal display, a printer, a portable device, etc. are mentioned, for example.

Next, the effects of the present embodiment will be described.
(1) In the method of manufacturing a flexible laminate, the insulating film 11 made of liquid crystal polymer and the metal foil 12 are continuously supplied between a pair of endless belts 23 and 24, and the insulating film 11 is formed between the endless belts 23 and 24. And the metal foil 12 to form a flexible laminate 10 by thermocompression bonding.

  In the thermocompression bonding step, the maximum temperature (first temperature T1) of the flexible laminate 10 is in the range of 45 ° C. or more lower than the melting point of the liquid crystal polymer constituting the insulating film 11 and 5 ° C. lower than the melting point The outlet temperature (second temperature T2) of the flexible laminate 10 when it is carried out of the endless belts 23 and 24 by heating the flexible laminate 10 to a temperature that is 235.degree. 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 to a temperature not higher than 100 ° C. lower than the melting point.

  According to the above configuration, it is possible to reduce the dimensional change rate of the flexible laminate 10, particularly the dimensional change rate before and after the heat treatment at 250 ° C. 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 during reflow soldering for mounting various elements. It is important from the viewpoint of high density mounting to suppress the dimensional change of the flexible laminate 10 at this time. Therefore, the flexible laminated board 10 in which the dimensional change rate before and after heat treatment at 250 ° C. is reduced is useful as a material of a flexible printed circuit board for high density mounting.

In addition, it is also possible to change and implement this embodiment as follows.
In the above embodiment, the metal foil 12 is thermocompression-bonded to both sides of the insulation film 11, but the metal foil 12 is thermocompression-bonded to only one side of the insulation film 11 to form a flexible laminate having a metal layer on one side of the insulation 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 taken up in a roll shape is provided for the feeding unit 30. Then, in the thermocompression bonding step, the metal foil 12 drawn out from the metal foil roll 32 is superimposed on one side of the insulation film 11 drawn out from the insulation film roll 31 of the drawing portion 30. These are continuously supplied to the double belt press 20 while overlapping the release film 13 drawn out from the release film roll 33 on one side. The flexible laminated board 10 carried out of the double belt press apparatus 20 is collected by being wound up in a roll shape in the winding unit 40 while the release film 13 is in a stacked state. The heating conditions and pressurizing conditions in this thermocompression bonding step are the same as those 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 20 in the thermocompression bonding process. As the release film 13, the well-known release film used for manufacture of a flexible laminated board can be used. In particular, using a flexible material having high heat resistance and good releasability, for example, a release film made of at least one selected from heat-resistant non-thermoplastic aromatic polyimides, fluorocarbon resins, and silicone resins preferable.

  In addition, when using the flexible laminated board 10, the mold release film 13 peels suitably. In addition, a recovery roll for recovering the release film 13 is separately provided in the winding unit 40, and flexible lamination is performed while peeling the release film 13 from the flexible laminate 10 at the timing of being carried out from the double belt press device 20. The plate 10 and the release film 13 may be collected separately.

Next, the embodiment will be more specifically described by way of examples and comparative examples.
(Examples 1 to 13, Comparative Examples 1 to 12)
Using a double belt press, various heating conditions in the thermocompression bonding process were set, a flexible laminate having a metal layer 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 step 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. It is the range of <T2 <mp-100 degreeC "(100 degreeC <T2 <235 degreeC). 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 the heating conditions of materials etc. are as follows.
Metal foil: Rolled copper foil (JX manufactured by JI Nippon Mining & Co., Ltd., BHYX-92-HA).
Insulating film: LCP film (manufactured by Kuraray, Bexter CTZ, melting point 335 ° C.).

Release film: Polyimide film (manufactured by Ube Industries, UPILEX S, thickness 25 μm). In addition, the release film peeled from the flexible laminated board after the thermocompression-bonding process.
Pressure: 4.0MPa
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, when heating temperature was changed into 150 degreeC and 250 degreeC, the dimensional-change rate of the flexible laminated board in was measured. The results are shown in Tables 1 and 2.

(Evaluation of uneven thickness)
A 50 mm × 520 mm wide sample was taken from the flexible laminates of Examples and Comparative Examples, and the metal layer was removed by etching for this sample. And about the insulating layer which remained, thickness at 52 points was measured at intervals of 10 mm in the width direction using a hitting type thickness meter, and its standard deviation was calculated. The results are shown in Tables 1 and 2.

(Evaluation of peel strength)
The peeling strength (peel strength) of the metal layer was measured about the flexible laminated board of an Example and a comparative example using the test method prescribed | regulated to JISC6471. The results are shown in Tables 1 and 2.

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

  From the comparison of Examples 2, 4, 6, 8, 10 and Comparative Examples 2, 4, 6, 8, 10, when the second temperature T2 is higher than "mp-100 ° C" (235 ° C) In the results, the dimensional change rate in the test at 150.degree. C. and 250.degree. C. was greatly increased more than twice.

  From the comparison between Example 1 and Comparative Examples 11 and 12, when the first temperature T1 is 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 is that the rate is greatly increased more than twice.

Further, 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 in the above range, the dimensional change rate before and after heating at 250 ° C. can be reduced while securing the quality such as thickness unevenness and peel strength. It could be confirmed. In addition, it has been confirmed that there is no problem in terms of mass productivity of the flexible laminate. Such effects were the same as 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 was used (Example 13). Furthermore, although detailed data will be omitted, when using a 12 μm thick electrolytic copper foil (3EC-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.) as a metal foil, another LCP film (Primatech Co., Ltd.) as an insulating film Similar results were obtained when using company company, BIAC-BC, melting point 315 ° C., thickness 50 μm).

  DESCRIPTION OF SYMBOLS 10 ... Flexible laminated board, 11 ... Insulating film, 12 ... Metal foil, 13 ... Releasing film, 20 ... Double belt press apparatus, 21 ... Upper drum, 22 ... Lower drum, 23, 24 ... Endless belt, 25 ... Thermal Pressure device, 30: Delivery part, 31: Insulation film roll, 32: Metal foil roll 32, 33: Releasing film roll, 40: Take-up part.

Claims (4)

A flexible laminate comprising: an insulating layer made of liquid crystal polymer; and a metal layer formed on one side or both sides of the insulating layer,
The liquid crystal polymer, the liquid crystal polymer der Rutotomoni the melting point of higher than 250 ° C., ethylene terephthalate and a liquid crystal polymer with the structural unit parahydroxybenzoate, liquid crystal polymer as constituent units phenol and phthalic acid and p-hydroxybenzoic acid, A liquid crystal polymer selected from liquid crystal polymers having 6-hydroxy-2-naphthoic acid and parahydroxybenzoic acid as structural units,
In the dimensional stability test defined in JIS C 6471, the dimensional change when the heating temperature is 250 ° C. is in the range of ± 0.05%,
The flexible laminated board characterized by the standard deviation of the thickness in the width direction of the said insulating layer being 1.2 micrometers or less. A method of manufacturing a flexible laminate, comprising
An insulating film made of liquid crystal polymer and metal foil are continuously supplied between a pair of endless belts, and the insulating film and the metal foil are thermocompression-bonded between the endless belts to form a flexible laminated plate Have
The liquid crystal polymer is a liquid crystal polymer having ethylene terephthalate and parahydroxybenzoic acid as a constitutional unit, a liquid crystal polymer having phenol and phthalic acid and parahydroxybenzoic acid as a constitutional unit, 6-hydroxy-2-naphthoic acid and parahydroxybenzoic acid A liquid crystal polymer selected from liquid crystal polymers having
In the thermocompression bonding step,
The flexible laminate is heated such that the maximum temperature of the flexible laminate is in the range of 45 ° C. or more lower than the melting point of the liquid crystal polymer constituting the insulating film and 5 ° C. lower than the same melting point.
The outlet temperature of the flexible laminate at the time of being carried out from the endless belt is in the range of not less than 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 of manufacturing a flexible laminate, comprising: slow cooling the flexible laminate. As the insulating film, a liquid crystal polymer as constituent units 6-hydroxy-2-naphthoic acid and p-hydroxybenzoic acid, and characterized in that its melting point is used an insulating film composed of a liquid crystal polymer in excess of 250 ° C. The manufacturing method of the flexible laminated board of Claim 2.   The flexible film according to claim 2 or 3, wherein at least one metal foil selected from copper foil, aluminum foil, stainless steel foil, and foil made of an alloy of copper and aluminum is used as the metal foil. Method of manufacturing laminates.