JP2005059543A - Mold releasing material and method of manufacturing circuit board structure using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an adhesive from protruding or oozing when a structural member is bonded to a resin substrate and prevent the resin substrate from warping or curling after they are bonded, in a mold releasing material used for covering the surface of the rugged surface formed on at least a part of the surface of the resin substrate, when the component member is bonded to a part of the surface of the resin substrate. <P>SOLUTION: The mold releasing material 10 is used for covering the surface of the rugged surface formed on at least a part of the surface of the resin substrate 21 when a cover film 40 is bonded to a part of the surface of the resin substrate 21 and comprises an aluminum foil 11 and a fluororesin layer formed for covering at least a part of the surface of the aluminum foil 11. The method for manufacturing a circuit board structure comprises the steps of laminating the cover film 40 through an adhesive layer 30 on a circuit layer 23 formed on the surface of the resin substrate 21 and arranging the mold releasing material 10 on the same and heating and pressing it. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mold release material and a method for producing a circuit board structure using the mold release material, and more particularly to a mold release material used when producing a resin substrate circuit board structure.

  In a circuit board such as an FPC (flexible printed circuit) board, a resin base circuit board, or an IC card board, a circuit layer made of a metal thin film is formed on the surface of a resin substrate such as a resin board or a resin film. When these circuit boards are put into practical use, the circuit layer is covered with an insulating cover film. This coating is for preventing a short circuit on the circuit layer (short circuit) or preventing the circuit layer itself from being deteriorated by moisture or oxygen in the air.

  In recent years, electronic devices such as mobile phones, mobile personal computers, electronic notebooks, PDAs, mobile audio devices, mobile TVs, car navigation systems, and the like have been remarkably miniaturized. With the miniaturization, higher insulation and durability are required for circuit boards applied to electronic devices. In order to meet this requirement, it is becoming possible to cover a circuit layer with a cover film.

  As a method of covering the circuit layer with the cover film on the circuit board, the cover film is laminated on the surface of the resin base material with a thermal adhesive interposed so as to cover the circuit layer on the surface of the resin base material, and then heated. There is a method in which these are integrated and fixed by applying pressure. After the circuit layer is covered with a cover film, electronic components such as an IC, a capacitor, a transistor, a diode, and a connector are mounted on the circuit board. Usually, a cover film is not laminated on a circuit layer portion where an electronic component is to be mounted. For this reason, in the circuit board, there are a portion where the cover film is laminated and a portion where the cover film is not laminated, and a step is generated between them. Thereby, an uneven part is formed on the surface of the resin base material. In this state, the circuit layer is covered with a cover film except for the circuit layer part to be mounted on the electronic component, and when the heat film is heated and pressed to integrate the cover film with the resin substrate, the part where the thermal adhesive does not exist Oozes or oozes out. As a result, the thermal adhesive adheres to unnecessary portions on the circuit board. As a result, the mounting of electronic components is hindered in a later process.

  In order to prevent the thermal adhesive from protruding or oozing out, it is possible to use a release film for producing a printed circuit board having a specific composition and configuration, for example, Japanese Patent Laid-Open No. 2000-263724 (Patent Document 1). ).

  However, since this release film is made of resin, the effect of preventing the thermal adhesive from protruding or exuding was not sufficient. Moreover, since the resin release film has a low thermal conductivity, the time required for the heating and pressurizing step for the above integration becomes longer, and the time required for the subsequent cooling step becomes longer, and the work efficiency is improved. It was very bad. Further, the resin release film is likely to warp when heated. As the resin release film warps, there is a problem that the circuit board itself follows and warps or curls.

  On the other hand, for example, Japanese Patent Publication No. 4-9 includes a release agent for a resin-based printed circuit board, and a coating agent obtained by mixing silicone as a release agent with an epoxy resin on one or both sides of an aluminum foil. Conventionally known as disclosed in (Patent Document 2).

  This type of release material is effective as a release material used when press-molding a prepreg having a flat surface by heating and pressing. Here, the prepreg means a glass cloth or paper impregnated with an epoxy resin, a phenol resin, a polyimide resin or the like and then dried and semi-cured into a sheet shape.

However, when this type of release material is used when the resin base material on which the circuit layer made of the metal thin film is formed and the cover film are bonded and integrated, the components contained in the mixture of the epoxy resin and the silicone are reduced. Since it diffuses into the thermal adhesive layer to form an electrical path between the cover film and the circuit layer, the insulation of the cover film may be lowered.
JP 2000-263724 A Japanese Patent Publication No. 4-9

  Accordingly, one object of the present invention is to provide a separation member used for covering the surface of the concavo-convex portion formed on at least a part of the surface of the resin base material when the component member is fixed to the part of the surface of the resin base material. In the mold material, the adhesive is prevented from sticking out or oozing out when the constituent members are fixed.

  Another object of the present invention is to provide a release material used for covering the surface of the concavo-convex portion formed on at least a part of the surface of the resin base material when the component member is fixed to the part of the surface of the resin base material. (2) is to prevent warping or curl deformation of the resin base material which occurs after the component members are fixed.

  Still another object of the present invention is to provide a separation member used to cover the surface of the concavo-convex portion formed on at least a part of the surface of the resin base material when the component member is fixed to the part of the surface of the resin base material. In the mold material, it is to improve heat dissipation after fixing the constituent members and improve workability and productivity in the method of manufacturing a circuit board structure.

  The mold release material according to the present invention is a mold release material used to cover the surface of the concavo-convex portion formed on at least a part of the surface of the resin base material when the component member is fixed to the part of the surface of the resin base material. An aluminum foil and a fluorine-based resin layer formed so as to cover at least part of the surface of the aluminum foil are provided.

  In the release material of the present invention, the shape of the aluminum foil follows the shape of the above-described uneven portion in accordance with the pressure applied when the constituent members are fixed. For this reason, it is used to fix the constituent member and the resin base material, and it is effective that the adhesive interposed between them protrudes or exudes onto the surface of the unnecessary resin base material where the constituent member does not exist. Can be prevented.

  Further, in the release material of the present invention, since the fluororesin layer is formed so as to cover at least a part of the surface of the aluminum foil, it is like a resin film by heat applied when the constituent members are fixed. There is no irreversible thermal shrinkage. For this reason, it is possible to prevent warping or curl deformation of the resin base material that occurs after fixing according to the heat applied at the time of fixing the constituent members.

  Furthermore, in the release material of the present invention, since aluminum foil is used as a constituent material, the aluminum foil having high thermal conductivity plays a role of improving heat dissipation after the constituent members are fixed. For this reason, in the manufacturing method of a circuit board structure, since the time required for heating and cooling when fixing the constituent members can be shortened, workability and productivity can be improved.

In the release material of the present invention, the difference between the tensile strength and yield strength of the aluminum foil is in the range of 20 N / mm ² or more 70N / mm ² or less. In this case, since the moldability of the aluminum foil can be improved, the shape of the aluminum foil can be made to follow the shape of the concavo-convex portion better according to the pressure applied when the constituent members are fixed.

  In the release material of the present invention, it is preferable that the thickness of the aluminum foil is 6 μm or more and 50 μm or less and the surface roughness Rmax is 1 μm or less. In this case, it is possible to prevent a minute gap from being formed between the release material and the resin base material when the constituent member is fixed, and an adhesive is provided on the surface of the unnecessary resin base material where no constituent member is present. It is possible to more effectively prevent the protrusion or the bleeding.

  In the release material of the present invention, the fluorine resin is a fluoroethylene resin, an ethylene-fluorinated ethylene copolymer resin, a perfluoroalkyl copolymer resin, a perfluoropolyether copolymer resin, a urethane fluoride resin. It is at least one selected from the group consisting of a resin, a fluoroalkylsilane resin, a fluorophosphate resin, a silicon fluoride resin, a modified fluorine resin, a polyvinylidene fluoride, and a fluoroethylene vinyl ether copolymer. preferable.

In the release material of the present invention, formation of the fluorine resin layer is 0.05 g / m ² or more 4.0 g / m ² or less, the contact angle is 90 degrees or more at which a water droplet on the surface of the fluorine resin layer is in contact Is preferred. In this case, it is possible to more effectively enhance the releasability of the release material from the adhesive layer after the component members are fixed.

  The release material of the present invention is used for fixing the cover film on the surface of the resin base material with an adhesive layer interposed so as to cover the circuit layer formed on the surface of the resin base material. Is preferred.

  A method of manufacturing a circuit board structure according to the present invention includes a step of forming a laminate by laminating a cover film with an adhesive layer interposed on a circuit layer formed on a surface of a resin base material. And a step of disposing a release material having at least one of the above-described features on the laminate, and a step of heating and pressurizing the laminate through the release material.

  In the method for manufacturing a circuit board structure according to the present invention, it is preferable that the cover film and the adhesive layer are integrated in advance in the step of forming the laminate.

  According to this invention, it is used for fixing the component member and the resin base material, and the adhesive interposed between them protrudes or oozes out on the surface of the unnecessary resin base material where the component member does not exist. Can be effectively prevented.

  Further, it is possible to prevent warping or curl deformation of the resin base material that occurs after fixing according to the heat applied at the time of fixing the constituent members.

  Furthermore, in the method of manufacturing a circuit board structure, the time required for heating and cooling when fixing the constituent members can be shortened, so that workability and productivity can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view showing a schematic structure of a release material as one embodiment of the present invention. As shown in FIG. 1, the release material 10 includes an aluminum foil 11 and a fluorine resin layer 12 formed so as to cover the surface of the aluminum foil 11.

  FIG. 2 is a cross-sectional view showing a schematic configuration of a circuit board as an object in which the release material of the present invention is used. As shown in FIG. 2, the circuit board 20 includes a resin base material 21 and a circuit layer 23 formed on a partial surface of the resin base material 21 according to a wiring circuit pattern with an adhesive layer 22 interposed therebetween. Is done.

  FIG. 3 is a schematic cross-sectional view showing a state in which a cover film is laminated on a part of the circuit layer of the circuit board shown in FIG. As shown in FIG. 3, a cover film 40 is laminated on the circuit layer 23 with an adhesive layer 30 interposed so as to cover a part of the circuit layer 23 formed on the surface of the resin base material 21. Yes. At this time, the cover film 40 and the adhesive layer 30 may be integrated in advance.

  FIG. 4 is a schematic cross-sectional view showing a state in which the release material of the present invention shown in FIG. 1 is applied to integrate and fix the cover film shown in FIG. 3 to the circuit board. As shown in FIG. 4, the release material 10 is used when a cover film 40 is fixed to a partial surface of the circuit board 20 as a constituent member. When the cover film 40 is fixed, concave portions and convex portions are formed on a partial surface of the circuit board 20 as shown in FIG. The release material 10 is used to cover the surfaces of these concave and convex portions. In this manner, the laminate is heated and pressurized through the release material 10 in a state where the release material 10 is disposed on the laminate in which the cover film 40 is laminated on the circuit layer 23 on the surface of the resin base material 21. Thereby, the cover film 40 is integrated and fixed to the circuit board 20.

  At this time, the mold release material 10 is deformed following the shape of the concave and convex portions depending on the formability of the aluminum foil 11, so that the adhesive layer 30 protrudes to unnecessary portions of the circuit board 20, or It is possible to prevent bleeding. Further, in this step, the aluminum foil 11 constituting the release material 10 is not irreversibly heat-shrinked like a resin film, so that the circuit board 20 is not warped or curled. Furthermore, since the heat release property of the release material 10 is superior due to the presence of the highly heat conductive aluminum foil 11, the time required for heating and cooling in this step is short. Therefore, workability and productivity can be improved by using the release material 10.

  In one embodiment of the release material 10 of the present invention, the aluminum foil 11 can be an aluminum foil having a known composition, such as an industrial pure aluminum foil or aluminum having a composition defined by JIS or AA. Alloy foil, specifically, 1000 series pure aluminum, 3000 series aluminum alloy such as 3003 and 3004, 5000 series aluminum alloy such as 5052, and 8000 series aluminum alloy foil such as 8021 and 8079 can be employed.

  The thickness of the aluminum foil is preferably 6 μm or more and 50 μm or less, and more preferably 15 μm or more and 30 μm or less. If the thickness of the aluminum foil is less than 6 μm, there is a risk of cracking when using the release material. When the thickness of the aluminum foil exceeds 50 μm, not only the material cost as a release material increases, but also the flexibility is insufficient, and it becomes difficult to deform following the shape of the concavo-convex part during pressurization. Overhang may occur.

  The surface roughness Rmax of the aluminum foil is preferably 1 μm or less, and more preferably 0.01 μm or more and 1 μm or less. If the surface roughness Rmax of the aluminum foil exceeds 1 μm, there is a possibility that a minute gap is generated between the aluminum foil and the circuit board during pressurization, and the adhesive cannot be sufficiently prevented from protruding. In order to set the surface roughness Rmax of the aluminum foil to 1 μm or less, the roll surface roughness of the rolling roll may be appropriately adjusted by polishing or the like during the production of the aluminum foil.

  The tempering of the aluminum foil can be applied to any of an annealed material (O material), a rolled material (H material), and an intermediate material (semi-hard material) thereof. In consideration of flexibility, follow-up to the shape of the concavo-convex portion at the time of pressurization, cleanliness of the foil surface, etc., it is preferable to use an annealed material (soft material, O material). The annealing conditions are usually kept at an arbitrary temperature within the range of 250 ° C. or higher and 550 ° C. or lower for about 30 minutes to several tens of hours and then gradually cooled.

In addition, before coating the surface of the aluminum foil with the fluorine resin layer, the mechanical properties of the aluminum foil are as follows: the tensile strength is 75 N / mm ² or more, and the proof stress is 20 to 70 N / mm ² lower than the tensile strength. The elongation is preferably 1% or more. The aluminum foil used for the release material of the present invention must have a mechanical property that can be deformed following the shape of the concavo-convex portion as shown in FIG. In particular, as shown in FIG. 4, the surface of the concavo-convex portion having a space between the bulges (width of the dent) of 2000 to 3000 μm, a width of the bulge of about several hundred μm, and a height of the concavo-convex portion of about 100 μm and, in order to provide a deformable formability following this surface shape, it is required that the difference between the tensile strength and yield strength of the aluminum foil is in the 20 N / mm ² or more 70N / mm ² in the range . When the difference between the tensile strength and proof stress of the aluminum foil is less than 20 N / mm ² , the stress until the aluminum foil starts plastic deformation is relatively high, that is, it is difficult to deform with low stress, and plastic deformation starts. After that, the stress width or strain width until the aluminum foil breaks becomes narrow, and the formability deteriorates. If the difference between the tensile strength and the proof stress of the aluminum foil exceeds 70 N / mm ² , the proof strength becomes extremely low, the aluminum foil is unnecessarily plastically deformed, and the necessary smoothness cannot be maintained, and dimensional stability It will lack sex.

  In order to adjust the difference between the tensile strength and the proof stress of the aluminum foil, the composition of the aluminum alloy is appropriately selected, and appropriate annealing conditions are mainly selected. The composition of the aluminum alloy may be selected from, for example, the composition of the aluminum wrought material defined by JIS or AA. Specifically, it is 1000 series pure aluminum, 3000 series aluminum alloys such as 3003 and 3004, and 5000 such as 5052. What is necessary is just to select from 8000 type | system | group aluminum alloys, such as a type | system | group aluminum alloy and 8021, 8079. However, the annealing conditions are affected by the type and capacity of the furnace, the rolling history of the aluminum foil, the type and amount of rolling oil, the size of the aluminum foil coil, etc., so the optimum conditions must be selected each time through experiments. Don't be.

  In addition, before coating | covering a fluorine resin layer, you may wash | clean the surface of aluminum foil with water, a detergent, an acid, an alkali, or an organic solvent as needed.

  The mold release material of the present invention can be obtained by coating the fluororesin on at least a part of the surface of the aluminum foil, preferably on one side or both sides. Fluorine resins include fluorinated ethylene resins, ethylene-fluorinated ethylene copolymer resins, perfluoroalkyl copolymer resins, perfluoropolyether copolymer resins, fluorinated urethane resins, and fluorinated alkyl silane resins. At least one selected from the group consisting of resins, fluorophosphate resins, silicon fluoride resins, modified fluorine resins, polyvinylidene fluoride, and fluoroethylene vinyl ether copolymers can be used.

  The coating (coating) method is not particularly limited, and methods such as brush coating, bar coater, roll coater, doctor blade, gravure coating, spray coating, and dipping may be employed. When applying the fluororesin, it may be diluted with an appropriate solvent such as perfluorocarbon or hydrochlorofluorocarbon.

Formation of the fluorine-based resin layer (fluorine-based coating weight of the resin) is preferably at 0.05 g / m ² or more 4.0 g / m ² or less by weight after drying, fluorine-based resin layer within this range Exhibits good releasability. When the amount of the fluororesin layer formed is less than 0.05 g / m ² , the release effect is insufficient. When the amount of the fluororesin layer formed exceeds 4.0 g / m ² , it becomes excessive, and not only a further improvement in releasability is observed, but also cracking or peeling may occur during molding.

  Further, as shown in FIG. 5, the contact angle θ when the water droplet 50 is in contact with the surface of the fluororesin layer 12 covering the surface of the aluminum foil 11 is preferably 90 degrees or more. If the contact angle θ is less than 90 degrees, the releasing effect may be poor, and dust or dust is likely to be adsorbed.

  As the cover film, various known films can be adopted as long as they are insulating films, but considering moisture resistance, durability, etc., a polyimide film, a polyester film, a polybalavanic acid film, a polyphenylene sulfide film, an aramid film, etc. Is preferred. Although the thickness of a cover film is arbitrary, it is preferable that they are 9 micrometers or more and 50 micrometers or less, and it is more preferable that they are 12 micrometers or more and 25 micrometers or less.

As the adhesive (adhesive layer 30 in FIG. 4) used for bonding the cover film and the circuit board, a known adhesive or a thermoplastic resin can be used. For example, polyester, acrylic, ethylene- Examples thereof include an ethyl acrylate copolymer, an ethylene-methyl acrylate copolymer, and an epoxy type. Also, use commercially available products such as epoxy adhesives manufactured by Sumitomo Chemical Co., Ltd., product name “Mersen M” manufactured by Tosoh Corporation, and product name “BX-60” manufactured by Toagosei Co., Ltd. Can do. The thickness of the adhesive layer is not particularly limited, but is preferably 10 μm or more and 25 μm or less, and in the case of coating, it is preferably 10 g / m ² or more and 25 g / m ² or less by weight after drying. .

  In addition, if the resin base material itself used for a circuit board has thermal adhesiveness, an adhesive agent (adhesive layer 30 in FIG. 4) can also be abbreviate | omitted. Examples of such a resin include amorphous polyethylene terephthalate resin. In addition, the adhesive may be previously coated on the cover film in a separate step, and coated by a known method such as extrusion coating or roll coating.

  Any circuit board may be used as long as a circuit layer made of a metal thin film is formed on the surface of a resin substrate or resin film as a resin base. For example, an FPC (flexible printed circuit) board, a resin base circuit Examples include substrates and IC card substrates. The metal thin film is formed by etching a metal foil such as an aluminum foil into a circuit shape, applying a metal plating on a resin film (substrate) to form a circuit, and chemically treating a metal on a resin film (substrate). It may be any one of those formed in a circuit shape by physical vapor deposition or physical vapor deposition, or those obtained by bonding metal wires.

In order to bond the circuit board and the cover film, the above-mentioned adhesive is interposed, or if the resin base material itself used for the circuit board has thermal adhesiveness, the adhesive is not interposed. What is necessary is just to heat moderately by applying pressure with a press etc. from both directions of the upper surface of a cover film and the lower surface of a circuit board through a mold material. The heating temperature may be appropriately determined depending on the type and amount of the above adhesive, but is usually 60 ° C. or higher and 260 ° C. or lower. The pressure may be appropriately determined depending on the kind of the adhesive and the like, but is usually 5 kg / cm ² or more and 40 kg / cm ² or less. In addition, when applying a pressure, it is preferable to use a cushion material, and it is preferable to interpose a cushion material between the press surface of a press machine and said mold release material. As the cushion material, a known resin film, foam sheet, rubber sheet, elastomer sheet, or the like can be used.

  As described below, the release material of the present invention was produced in Examples 1 and 2. For comparison, a mold release material made of an aluminum foil coated with a resin mold release material and a resin different from the present invention was produced in Comparative Examples 1 and 2.

Example 1
Thickness of 20 [mu] m, a tensile strength of 75N / mm ^2, yield strength is 30 N / mm ^2, the surface roughness Rmax of 0.5μm aluminum foil (composition: 1N30, temper: O) on one side of the steel Fine Chemical Japan Co., Ltd. Product name FSG guard FC-109 (main component: fluoroethane) was applied and coated at a coating amount of 0.1 g / m ² . Drying conditions after coating were 15 seconds at a temperature of 200 ° C. After the coating process, the abrasion resistance was evaluated with MEK (methyl ethyl ketone) to confirm that the resin layer covering the surface of the aluminum foil was not peeled off and the resin layer was cured.

(Example 2)
On one side of an aluminum foil (composition: 1N30, tempering: O) having a thickness of 15 μm, a tensile strength of 78 N / mm ² , a proof stress of 35 N / mm ² and a surface roughness Rmax of 0.45 μm, manufactured by Fine Chemical Japan Co., Ltd. Product name Fine fluorinated silane coat (main component: mixture of fluorinated tetra-silane and fluorophosphate) was applied at a coating amount of 0.1 g / m ² . Drying conditions after coating were 15 seconds at a temperature of 120 ° C. After the coating process, the wear resistance was evaluated with MEK to confirm that the resin layer covering the surface of the aluminum foil was not peeled off and the resin layer was cured.

(Comparative Example 1)
Using a resin film of Mitsui Petrochemical Co., Ltd. product name Opyran M-210L (TPX: 4-methyl-1-pentene polymer resin) with a thickness of 40 μm, a release material made of a single layer resin film was produced. .

(Comparative Example 2)
Paste resin films of product name Opylan M-210L (TPX: 4-methyl-1-pentene polymer resin) manufactured by Mitsui Petrochemical Co., Ltd. with a thickness of 40 μm on both sides of a polyethylene (PE) film with a thickness of 60 μm. In combination, a release material composed of a three-layer resin film was prepared.

(Comparative Example 3)
Thickness of 25 [mu] m, a tensile strength of 226N / mm ^2, yield strength is 209N / mm ^2, the surface roughness Rmax of 2.5μm aluminum foil (composition: 3003, refining: H) on one side of, with a polyorganosiloxane chain The product name full shade U3H, which is a compound, was applied and processed at an application amount of 2 g / m ² . Drying conditions after the application were at a temperature of 150 ° C. for 20 seconds. After the coating process, the wear resistance was evaluated with MEK to confirm that the resin layer covering the surface of the aluminum foil was not peeled off and the resin layer was cured.

  The release properties, wettability (initial contact angle of water droplets), contamination degree, followability, and curl deformation of the release materials prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated. The evaluation results are shown in Table 1.

  Each evaluation condition is as follows.

(Releasability evaluation)
As shown in FIG. 6, FPC adhesive (product name BX-60, epoxy adhesive) manufactured by Toa Gosei Co., Ltd. was applied to the surface of a polyimide film having a thickness of 12.5 μm as the cover film 40. The adhesive layer 30 was formed by applying at m ² . After drying, lamination was performed so that the surface of the resin layer 12 formed on one surface of the aluminum foil 11 as a release material overlaps the surface of the adhesive layer 30. The laminate was heated to a temperature of 150 ° C. under a pressure of 15 kg / cm ² and after 1 hour, the release characteristics of the release material were examined. In Comparative Examples 1 and 2, a release material made of a resin film was stacked on the surface of the adhesive layer 30 and laminated. In Table 1, since the release material was able to be completely peeled by hand, the mark “◯” is shown as indicating that the release characteristics are good.

(Evaluation of wettability (initial contact angle of water droplets))
As shown in FIG. 5, the wettability of the resin layer 12 as a release surface is determined by the contact angle of the water droplet by adhering the water droplet 50 onto the surface of the resin layer 12 formed on one side of the aluminum foil 11 as a release material. It was evaluated by θ. The contact angle θ was measured using a contact angle meter (CA-DT) manufactured by Kyowa Science Co., Ltd. In Comparative Examples 1 and 2, the wettability was evaluated by attaching water droplets on the surface of the release material made of a resin film.

(Pollution degree evaluation)
As shown in FIG. 7, using a flat plate (hot plate press) at a temperature of 150 with the surface of the soft aluminum foil 60 in contact with the surface of the resin layer 12 formed on one side of the aluminum foil 11 as a release material. Thermocompression bonding was carried out by holding for 1 minute under the conditions of ° C. and pressure of 15 kg / cm ² . Thereafter, the surface dyn number (surface tension) of the crimping surface of the soft aluminum foil 60 was measured. The surface dyn number of the surface of the soft aluminum foil before thermocompression bonding is 72 dyn / cm or more. The larger the value of the surface dyn number, the less the foreign matter adheres or diffuses, and the lower the degree of contamination. The surface dyn number was measured in accordance with JIS K6768. In Comparative Examples 1 and 2, the surface of the soft aluminum foil 60 was brought into contact with the surface of the release material made of a resin film.

(Evaluation of followability of release material to circuit layer pattern and curl deformation after peeling)
An adhesive was interposed on the surface of the polyimide film having a thickness of 25 μm to fix a copper foil having a thickness of 18 μm, and the copper foil was etched according to a predetermined circuit pattern. On this etched copper foil, the surface of the resin layer formed on one side of the aluminum foil as a release material was superposed and laminated. Using a cushioning material at a temperature of 180 ° C., the laminate was held for 5 minutes in a state where a pressure of 15 kg / cm ² was applied, and the followability of the release material to the circuit layer pattern of the copper foil was observed. Further, the state of curl deformation was observed in the polyimide film as the resin substrate of the circuit layer after the release material was peeled off. In Table 1, a case where the followability is good and there is no curl deformation is indicated by a circle, and a case where there is no followability and there is a curl deformation is indicated by a mark x. In Comparative Examples 1 and 2, the surface of the release material made of a resin film was superposed and laminated on the etched copper foil.

  From Table 1, the release materials of Examples 1 and 2 exhibit good release properties, are difficult to adsorb dust or dust, have low contamination, and have good followability of the release material to the circuit layer pattern. It can be seen that the circuit board was not curled even after the mold material was peeled off.

It is sectional drawing which shows the schematic structure of a mold release material as one embodiment of this invention. It is sectional drawing which shows schematic structure of the circuit board as a target object in which the mold release material of this invention is used. It is a schematic sectional drawing which shows the state which laminated | stacked the cover film on a part of circuit layer of the circuit board shown in FIG. FIG. 4 is a schematic cross-sectional view showing a state in which the release material of the present invention shown in FIG. 1 is applied to integrate and fix the cover film shown in FIG. 3 to the circuit board. It is a schematic sectional drawing which shows the state which made the water droplet adhere on the surface of the resin layer formed in the single side | surface of aluminum foil as a mold release material. It is sectional drawing which shows the structure of the laminated body for evaluating the mold release property of a mold release material. It is sectional drawing which shows the structure of the crimping | compression-bonding body used in order to evaluate the contamination degree of a mold release material.

Explanation of symbols

  10: release material, 11: aluminum foil, 12: fluorine resin layer, 20: circuit substrate, 21: resin substrate, 22: adhesive layer, 23: circuit layer, 30: adhesive layer, 40: cover film 50: Water droplets.

Claims (8)

A mold release material used for covering the surface of the concavo-convex portion formed on at least a part of the surface of the resin base material when fixing the constituent member to the part of the surface of the resin base material,
Aluminum foil,
A mold release material comprising: a fluororesin layer formed so as to cover at least a part of the surface of the aluminum foil. The difference between the tensile strength and yield strength of the aluminum foil is in the range of 20 N / mm ² or more 70N / mm ² or less, the releasing material according to claim 1.   The mold release material according to claim 1 or 2, wherein the aluminum foil has a thickness of 6 µm to 50 µm and a surface roughness Rmax of 1 µm or less.   The fluororesin is a fluorinated ethylene resin, an ethylene-fluorinated ethylene copolymer resin, a perfluoroalkyl copolymer resin, a perfluoropolyether copolymer resin, a fluorinated urethane resin, or a fluorinated alkylsilane. From claim 1 to claim 3, which is at least one selected from the group consisting of resins, fluorophosphate resins, silicon fluoride resins, modified fluorine resins, polyvinylidene fluoride, and fluoroethylene vinyl ether copolymers. The mold release material of any one of these. The formation amount of the fluorocarbon resin layer is 0.05 g / m ² or more 4.0 g / m ² or less, the contact angle is 90 degrees or more at which a water droplet on the surface of the fluorine resin layer are in contact, according to claim 1 The release material according to any one of claims 1 to 4.   The mold release material is used for fixing a cover film on the surface of the resin base material with an adhesive layer interposed so as to cover a circuit layer formed on the surface of the resin base material. The mold release material according to any one of claims 1 to 5. Forming a laminate by laminating a cover film with an adhesive layer interposed on a circuit layer formed on the surface of the resin substrate;
Disposing the release material according to any one of claims 1 to 5 on the laminate;
And a step of heating and pressurizing the laminate through the mold release material.   The method for manufacturing a circuit board structure according to claim 7, wherein the cover film and the adhesive layer are integrated in advance in the step of forming the laminate.

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