TWI360373B - - Google Patents

Description

1360373 IX. EMBODIMENT OF THE INVENTION [Technical Fields of the Invention] The present invention relates to a flexible printed wiring board for use in a flexible printed wiring board substrate or the like which is used as a wiring material for miniaturization and weight reduction of electronic equipment. The substrate manufacturing method is particularly a substrate for a flexible printed wiring board which is excellent in adhesion strength, flexibility, or dimensional change of a conductor and an insulating layer. [Prior Art] In recent years, the miniaturization of mobile phones, digital cameras, navigation devices, and other various electronic devices, which are highly functional, and the development of lightweight, are used as flexible printing of electronic wiring materials used in these applications. The requirements for miniaturization, multilayering, densification, and low dielectricization of the substrate (wiring substrate) are high. In the prior art, the substrate for a flexible printed wiring board is produced by laminating a polyimide film and a metal foil with a low-temperature-curable adhesive. However, the adhesive layer lowers the characteristics of the wiring substrate, and is particularly detrimental. The polyimide film has excellent heat resistance, flame resistance and the like. Further, another problem with the adhesive layer is that the circuit workability of the wiring is deteriorated. Specifically, there are problems in that resin residue is generated by drilling in the through hole processing, or the dimensional change rate is large when the through-hole is processed. In particular, in the case of a double-sided through-hole structure, it is generally softer than a flexible printed circuit board having a single-sided structure, which is formed by bonding a copper foil or the like on the both surfaces of the insulating layer to the base film by an adhesive. Low sex. On the other hand, with the increase in density of ICs, the miniaturization of printed wiring, and the high density of -5 to 1360373, it is necessary to bond with a good heat conductor due to heat generation. Further, since it is more refined, there is a method of integrating the outer casing and the wiring. Further, it is necessary to have a wiring having a different capacitance. Therefore, a method for producing a substrate for a flexible printed wiring board which is cured by heating without applying an adhesive directly to a conductor such as a copper foil and applying a polyamic acid solution before curing. For example, a polyamine containing a diamine and a tetracarboxylic anhydride having a linear expansion coefficient of a cured product of 3.0 X 1 0_5 or less is applied to a metal foil and then cured by heating (for example, see Patent Document 1). Or a solution containing a polyimine precursor compound compound resin having a specific structural unit coated on a conductor for oxime imidation (for example, refer to Patent Document 2), which will have a diamino benzanilide or a derivative thereof. The precursor solution of the insulating forest material of the structural unit obtained by the reaction of the diamine and the aromatic tetracarboxylic acid is directly applied to a conductor and cured (for example, refer to Patent Document 3). Further, in order to improve the adhesion to the metal foil, it is proposed to use a plurality of polyimine precursor resin solutions for the conductors to produce a substrate for a flexible printed wiring board having a plurality of polyimine resin layers by coating and drying a plurality of times. (For example, refer to Patent Document 4) Guide 乂 乂 1 曰 特 专利 专利 专利 专利 专利 专利 专利 专利 专利 日本 62 62 62 62 62 62 62 62 62 62 62 62 -2 -2 -2 62-84 Japanese Unexamined Patent Publication No. Hei. No. Hei. No. Hei. The method is widely used in the field of advanced electronic parts which can obtain high adhesion between a conductor and a polyimide layer which is an insulating layer and which requires high functionality. However, in this method, the polyimine precursor material is imidized by heating, but after the heat treatment, there is insufficient adhesion between the conductor layer and the insulating layer, and the adhesion force is uneven during heat treatment of the long substrate, and uniform quality is not easily obtained. A product of a substrate for a flexible printed wiring board cannot provide a product that satisfies market requirements. It is an object of the present invention to provide a method for producing a substrate for a flexible printed wiring board which has improved adhesion between a conductor layer and an insulating layer after heat treatment of a polyimide substrate resin. [Means for Solving the Problem] The inventors of the present invention have found that the adhesion of the polyimine precursor resin to the imidimination is maintained for a certain period of time in a specific maximum temperature range, and the adhesion is improved. The phenomenon completes the invention. In other words, the present invention is a method for producing a substrate for a flexible printed wiring board having a heat-cured single-sided insulating layer, which is coated with a polyimide film on one side of a conductor and then dried, and then dried. The method for producing a substrate for a flexible printed wiring board in which the maximum temperature during curing is in the range of 300 to 400 ° C and maintained at this temperature for 20 to 60 minutes. The heat curing according to the present invention is applied to the at least one resin layer side of the dried sheet-like substrate, and the air-permeable sheet-like material is brought into contact with the sheet-like material and then wound up on the cylindrical body to form a gas-permeable multilayer cylindrical body. In the state of -7- 1360373, it is ideal to move to the heating and hardening furnace for standing. Further, the hardening treatment in the heat-hardening furnace is carried out under the conditions of a reduced pressure or an inert gas. Further, in the hardening treatment of the heat-hardening furnace, it is an ideal embodiment to use a radiant heating means and a current flowing through the conductor of the multilayer cylindrical body to induce heating by the resistance of the conductor. [Effects of the Invention] According to the present invention, it is possible to produce a high-quality substrate in which the adhesion between the conductor and the insulating layer is improved and the adhesion to the long substrate is not uneven. [Best Mode for Carrying Out the Invention] The present invention will be described in detail below. First, the conductor used in the present invention may, for example, be a metal foil having a thickness of 5 to 15 〇em of copper, aluminum, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zinc, or the like, and is preferably Copper foil. As the copper foil, either rolled copper foil or electrolytic copper foil can be used. For the purpose of improving the adhesion, the surface may be treated with a chemical or mechanical surface such as a side wire, a shovel nickel, a copper-zinc-zinc alloy, or an alkoxy aluminum, an aluminum chelate or a decane coupling agent. . The term "polyimine precursor resin" refers to an insulating layer which is formed by heat-hardening to produce a quinone imine bond to form a polyimine-based resin layer having a quinone ring structure, which is represented by poly-proline. The polyimine-based resin to be an insulating layer may, for example, be a polyimide or a polyamidimide, a polyesterimide or the like. Therefore, the poly-imine resin layer is not particularly limited as long as it is a heat-expandable polyamidene resin which is melted or softened during heating by the heat-expansion of the low--8-36037 described in the above Patent Documents 1 to 4. A particularly preferable insulating layer is a two-layered thermoplastic resin polyimide resin layer formed of a low thermal expansion resin of 30 X 1 0_6 (1 / Κ) or less. It is preferably composed of at least three layers of a polyimide resin.

The low thermal expansion polyimine-based resin in which the main resin layer is formed is preferably 30 X 10-6 (1 / Κ) or less, and the film is excellent in heat resistance and flexibility. The coefficient of linear expansion is obtained by using a sample having sufficient hydrazine imidization reaction, and is heated to 250 ° C using a thermal mechanism analyzer (ΤΜΑ), and then cooled at a rate of 1 (TC / min, and obtained at 240 to 1). The average linear expansion coefficient in the range of 0 ° C. A specific example of the low thermal expansion polyimine resin having this property is a polyimide resin having a unit structure represented by the following general formula (I). Ideal.

(However, in the formula, R! to R4 are a lower alkyl group, a lower alkoxy group, a halogen group or a hydrogen). Further, the thermoplastic polyimine resin used in the upper and lower sides of the main resin layer has a glass transition temperature of 3 5 Any one of the unit structures may be used below 0 ° C, and it is desirable that the interface strength is sufficient when die-casting under heat and pressure. Here, the thermoplastic polyimine-based resin means that the fluidity does not necessarily have to be exhibited in a normal state above the glass transition point, and it is also possible to include -9 to 1360373 by heating. Specific examples of the thermally expandable polyimine-based resin having such a property include a unit structure represented by the following general formula (Π) or general formula (III). , co, (I) το. (However, in the formula, An is a divalent aromatic group and its carbon number is 12 or more) X0, C0, C0 - (I) (However, in the formula, Ar2 is a divalent aromatic The group of the group having a carbon number of 12 or more. Specific examples of the divalent aromatic group An or Ar2 herein are as follows. -00-0- v > -〇-c〇-0- -^-CO-NH-0- v -0-O-0SO2-0O-0- s -0-O-0-O-0- CH3

Ch3 -10- 1360373 The polyimine precursor solution coated on the conductor used in the present invention is substantially converted into the above-mentioned polyamidene-based resin, and a known acid anhydride-based or amine-based hardener may be added. Various additives or catalysts such as a curing agent such as a curing agent, a decane coupling agent, a titanate coupling agent, an epoxy compound, or the like, and a flexible bonding agent such as rubber. In particular, the conductor is laminated on the basis of the thermoplastic polyimine resin layer, the low thermal expansion polyimine resin layer of the central main layer, and the thermoplastic polyimide polyimide resin layer of the outermost layer. The third floor is ideal. Here, the central main layer must be a thermoplastic polyimine-based resin layer having a lower coefficient of thermal expansion than the thermoplastic polyimine-based resin layer above and below it. The main layer has a function of suppressing deflection or bending of the substrate for the manufactured flexible printed wiring board, and the thermoplastic polyimide layer in contact with the conductor has an effect of ensuring adhesion to the conductor, and the heat of the outermost layer The plastic polyimide layer is expected to be effective for suppressing the deflection of the film monomer. In this case, the ratio (ti / t2) of the thickness of the low thermal expansion polyimine resin layer of the main layer to the total thickness t2 of the thermoplastic polyimine resin layer on the upper and lower sides is in the range of 2 to 100. It is preferable that the range of 5 to 20 is preferable, and when the thickness ratio / t2) is less than 2, the thermal expansion coefficient of the entire polyimide layer is much higher than that of the conductor, and the obtained substrate for a flexible printed wiring board is obtained. The deflection or bending becomes large, and the workability at the time of loop processing is remarkably low. Further, when the thickness t2 of the thermoplastic polyimide layer is too small and the thickness ratio (t· / t2) exceeds 100, the adhesion to the conductor may not be sufficiently exhibited. As described in the above Patent Document 4, a plurality of precursor solutions are collectively or sequentially coated or ruthenium ring-opened in a form of a precursor solution of the plurality of -11 - 1360373 polyimine-based resins coated on the conductor. After the desolvation treatment is carried out below the temperature, it is preferred to carry out the heating conversion of the precursor polyimine in a single pass. When a polyimide-imide-based precursor solution is applied to the polyimine layer completely, and the heat treatment is carried out to carry out the ring closure of the quinone imine, the adhesion between the layers of the polyimide-based resin layers may not be sufficiently exhibited. The reason for the decline in quality. The method of applying a polyfluorene-based solution (poly-proline solution) to a conductor can be carried out by a known method using a knife applicator, a die applicator, a roller applicator, a curtain applicator, or the like. In particular, a die coater or a knife applicator is suitable when applying a thick coating. Further, the polymer concentration of the polyimide-based precursor solution used for coating differs depending on the degree of polymerization of the polymer, but is usually 5 to 30% by weight, preferably 10 to 20% by weight. When the concentration of the polymer is less than 5% by weight, a sufficient film thickness cannot be obtained by one application, and when the viscosity is more than 30% by weight, the viscosity of the solution becomes too high and it becomes difficult to apply the device used for drying. Any type can be used. It is preferable that the coated conductor described in the above Patent Document 4 is preferably a floating form that is not in contact with the device. The floating form is a method in which the coated conductor is dried in a continuous floating state in a hot air stream. The drying is usually carried out at 150 ° C or lower, preferably at 90 to 130 t, in a solvent of a polyimine-based precursor, and the solvent used for the resin at the time of coating is at least dried to remove the volatile matter such as a solvent. It is preferably 50% by weight or less, preferably 30% by weight or less, more preferably 10% by weight or less. When the solvent residue exceeds 50 -12 to 1360373% by weight, the surface of the resin remains viscous, and when it is wound into a cylindrical shape in the subsequent hardening treatment, it is bonded to the separator, and the resin property after heat curing is deteriorated. A polyamic acid solution having a uniform thickness is applied to the conductor, and the solvent is removed to half or less by a drying treatment, followed by heat hardening.

In the heat hardening of the present invention, the polyimine precursor resin solution is continuously applied to the conductor on the roller from the viewpoint of productivity, and is continuously floated in a floating air flow in the above-mentioned floating form, and then packaged into a package. It is preferably cylindrical, and it is preferably rolled to roll. In order to provide a good air permeability to at least the resin layer side of the dried sheet-like substrate at the time of package, a permeable sheet-like material such as a nonwoven fabric or a stainless steel mesh is preferably wound into a cylindrical body together with the air-permeable sheet-like material. It forms a permeable multi-layered cylinder. The multilayered cylinder is transferred to a suitable heat-hardening furnace, and is allowed to stand still and heat-harden the polyimide-based precursor resin layer. In this case, in order to alleviate the residual stress of the polyimide film layer at the time of temperature rise, it is preferable that the resin portion is wound inside and the resin is wound outward. In order to avoid deterioration by oxygen in the heating furnace, the conductive metal foil or the polyimide resin is preferably used in a gas atmosphere of an inert gas or a pressure reduction to 100 Torr or less, and is continuously performed under a reduced pressure of 5 Torr or less. More ideal. This is a smooth and complete removal of residual organic solvent generated in the coated resin and moisture or unreacted monomers generated in the ring-opening reaction of hydrazine imidization. In particular, when water remains in a gas atmosphere, hydrolysis of the resin is caused, and the degree of polymerization of the resin is lowered. As a result, there is a concern that the physical properties of the polyimide layer are lowered, and the conductor is caused by heat curing in the presence of oxygen. The oxidation is also the cause of the decline in quality. -13- 1360373 The heating means in the heating furnace for the hardening step is roughly divided into two stages: a stage in which degassing and desolvation are sufficiently performed, and a stage in which the hardening reaction is completed, that is, the temperature is first raised to 150 °C. On the left and right sides, it is preferable to gradually or gradually increase the temperature to the vicinity of the boiling point of the organic solvent, and it is preferable to sufficiently volatilize the residual solvent in the resin and gradually or gradually increase the temperature to 300 ° C or higher. More preferably, it is preferably carried out at a temperature elevation rate in the range of 0.75 to 12 °C/min. When the heating rate exceeds 12 ° C / min, the solvent is rapidly removed, and foaming in the resin is not preferable. When the temperature is lower than 0.7 5 t, the time until the highest temperature is too long, and the resin is exposed to a high temperature for a long period of time, which causes deterioration of the resin. Further, it is preferable that the conductors of the plurality of layers of the cylindrical body that are placed in the heat-hardening furnace are electrically connected to the conductor-connected power supply wiring and the electric resistance of the conductor is heated by the electric resistance of the conductor. Further, it is preferably carried out under vacuum in an inert gas atmosphere or at a temperature of 100 Torr or less, preferably after cooling and cooling to room temperature, more preferably under a vacuum of 10 Torr or less. The means for cooling may be placed only, and it is preferable to use a forced cooling means such as circulating cooling water in consideration of productivity. A polyamic acid solution having a uniform thickness on the conductive metal foil is applied, and the solvent is completely removed by a heat hardening treatment to further reduce the ring of the imide. At this time, in the case of rapid high-temperature treatment, it is preferable that the surface of the resin is formed into a film layer solvent which does not evaporate, causing foaming, and is preferably heat-treated while rising from a low temperature to a high temperature. The final heat treatment temperature at this time is preferably 300 to 400 ° C. At 400 ° C or higher, P starts to cause slow thermal decomposition of polyimine. Moreover, the film of polyimide at less than 300 ° C cannot be used for conductive metal foil. The alignment is sufficiently sufficient to obtain a single-sided conductor laminate having good planarity and excellent adhesion. -14- 1360373 Also, the time required for the final heat treatment temperature is preferably 20 to 60 minutes. At this time, the polyimide of the contact conductor is moderately melted and adhered well to the surface of the conductor, and it is presumed that the oxygen present in the heated gas atmosphere or the oxygen atom contained in the polyimide resin reacts with the conductor. The chemical combination of the quinone imine resin with the conductor surface enhances the adhesion. When the holding time is less than 20 minutes, the contact surface of the polyimide resin with the conductive metal foil does not cause sufficient melt flow, and the reaction of the oxime imidization cannot be sufficiently performed, and the desired bonding strength cannot be obtained. Further, for more than 60 minutes, it is not expected to improve the adhesion effect due to the imidization or the melting phenomenon at the interface. On the contrary, the polyamidene resin is decomposed, and the resin characteristics are remarkably lowered. The reel thus formed is wound up and wound up into the same reel before heating, and the flaky material is separated into a reel of product. The thickness of the polyiridide-based resin layer of the formed insulating layer is usually 10 to 150 μm.

[Embodiment] Hereinafter, embodiments of the present invention will be specifically described by way of examples and comparative examples. Further, in the following examples and comparative examples, the dimensional change ratio, the deflection and the adhesion of the single-sided copper-attached copper product, and the deflection of the film were measured by the following methods. The dimensional change rate is that the 250 mm square sample is placed at 4 intersections of the line 25 mm from each side and 25 mm at the midpoint of the opposite side of each side at the resin surface count 8 The dimensional change rate before and after removal of the copper foil was measured. The adhesion of the single-sided copper product is based on JIS C 5016: 7.1, -15-1360373. Using a model with a conductor width of 3 mm, the copper foil is stretched at a direction of 180° at 50 mm/min to determine the peeling time. The flexure of the film is to remove the copper foil from the 50 mm square single-sided copper paste in a chlorinated aqueous solution, wash and dry the film, and leave it at 23 ° C, humidity 50% for 24 hours. Originally, the copper foil was turned downside down on the horizontal plane and the amount of reverse bending or central bulging measured by the micrometer was measured. Further, the abbreviations used in the examples and comparative examples are as follows. PDMA: anhydrous pyromellitic acid BTDA: 3,3'4,4'-benzophenone tetradecanoate DDE: 4,4-diaminodiphenyl ether MABA: 2'-methoxy-4,4 '-Diaminobenzidine aniline (Synthesis Example 1) Into a glass reactor, 2532 g of hydrazine was introduced while passing nitrogen gas, and dimethyl dimethyl acetamide was placed under stirring to introduce 0.5 mol of DDE and 0.5 mol. The MABA is completely dissolved. The solution was cooled to 1 Torr. (: The reaction solution was kept at a temperature of 30 ° C or less to add 1 mol of PMda per little amount, and the junction rate was added, followed by stirring at room temperature for 2 hours to complete the polymerization. The polyimine precursor solution obtained by the reaction was obtained. The apparent viscosity at 25 ° C is 1 〇〇〇 mPa at a concentration of 15% by weight of the polymer and using a b-type viscosity. (Synthesis Example 2) Except that 1 mol of DDE is used as the diamine component, 1 mol of BTDA In the same manner as in the synthesis example 1, the polyiminoimine precursor solution was adjusted in the same manner as in the synthesis example 1. The obtained polyfluorene imine precursor solution of 160-1360373 was used at a concentration of 15% by weight of the polymer and at a temperature of 25 ° C using a b-type viscosity meter. The apparent viscosity was 300 mPa·s. Example 1 The roughened surface of the conductor (electrolytic copper foil) having a roughened surface and a glossy surface was coated with a solution of the polyimide precursor solution adjusted in Synthesis Example 2. After being applied to a uniform thickness of 15/m, it was dried at 130 ° C for 12 minutes. The polyimine precursor solution adjusted in Synthesis Example 1 was uniformly coated into 200 at 130 ° C to dry. The polyimine precursor solution adjusted in Synthesis Example 2 was coated into 20 ° at 130 ° C to dry the volatile solvent to obtain a polyfluorene. A flexible sheet-like substrate of a copper-coated product of an imide resin and a copper foil. At this time, the residual amount of the solvent in the resin was 〇·78% by weight, and the resin was dried and confirmed to have no stickiness. Ra=1.5 //m thickness 40"m aromatic polyamidene non-woven fabric

The air-permeable multilayer cylindrical body was obtained by laminating a copper foil with the inner side of the resin surface as a cylindrical body. The multiple multi-layer cylinders which are packaged together are placed in a cylindrical vacuum drying furnace, and the pressure in the furnace is reduced to 1 CT1 Torr, and the radiant heating means and the current flowing through the conductors of the multilayer cylinder are conductors. The resistance induction heating means gradually raises the temperature to a uniform temperature of 15 〇 ° C in the multilayer cylinder, and maintains the state for 2 hours, sufficiently desolvation, and then adjusts to 3 3 0 to 340 ° C for 2 hours. This temperature is maintained for 30 minutes. Then, after the furnace wall is cooled by the cooling water under the reduced pressure, the multi-layered reel is taken out from the furnace, and the substrate for the flexible printed wiring board in which the reel of the aromatic polyimine-based nonwoven fabric is separated is obtained by loosening the reel. . In the substrate for a flexible printed wiring board of -17 to 1360373, the conductor surface is of course free from scratches or dents, and there is no excellent article having a curved appearance. The subsequent force is 2.0 kg, the heating shrinkage is 0.05%, and the coefficient of linear expansion is 1 1 X 1 〇·6 (1 / welding heat resistance test does not have any heterogeneous phase. Moreover, the shiny side of the copper foil is not easy to form the desired pattern. Type. Convex / cm, K). Tin oxidation, Comparative Example 1 In Example 1, except for the final holding temperature of 260 ° C, the same test was carried out, and the obtained flexible printed wiring board substrate was connected to 0.5 kg / cm, the heat shrinkage rate was 0.03%, and the linear expansion was performed. The coefficient is 45 (1/K), the soldering heat test copper foil and the resin interface have multiple production lines. The full force is X 10^ raw peeling. Comparative Example 2 is in Example 1, except that the final holding temperature is 4500 °C. The same test was carried out, and the obtained flexible printed wiring board substrate was connected to 0.5 kg / cm, the heat shrinkage rate was 0.03%, the coefficient of linear expansion was 45 (1/K), and the interface between the solder heat-resistance test copper foil and the resin was obtained. There are a number of production lines that fully focus on xlO·6 peeling. Comparative Example 3 In Example 1, except for the final holding time of 1 〇 minutes, and the final degree is 260 ° C, the same test is performed, and the obtained flexible wire board is used. The substrate has an adhesion of 0.4 kg / cm, and the thermal shrinkage is 〇. The temperature is maintained. 05% > -18- 1360373 The coefficient of linear expansion is 36 X l〇·6 (1/K), the solder heat-resistance test copper foil There are many places where the interface with the resin is peeled off. [Industrial Applicability] According to the method for producing a substrate for a flexible printed wiring board of the present invention, it is possible to improve the adhesion between the conductor layer and the insulating layer after the heat treatment of the polyimide film of the polyimide, and to improve the long shape. The substrate is unevenly used for heat treatment, and is commercially available.

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Claims (1)

1360373 X. Patent Application No. 1. A method for manufacturing a substrate for a flexible printed wiring board, which comprises sequentially coating a polyimide resin precursor solution on one surface of a conductor, and heating it after drying treatment A method for producing a substrate for a flexible printed wiring board having a cured single-sided insulating layer, characterized in that each of the above polyimine precursor resin solutions is formed by a thermal expansion coefficient of 3 〇 xl (Γ6 (1/Κ) Each of the insulating layers of at least three layers of the polyimide-based resin-based resin in which the two layers of the thermoplastic resin-containing polyimide resin are disposed on the main resin layer of the lower heat-expandable resin layer In the resin layer, the maximum temperature during heat curing is in the range of 300 to 400 ° C, and is maintained at this temperature for 20 to 60 minutes, and the heat curing is performed on at least the resin layer side of the dried sheet-like substrate, so that The permeable sheet-like material is brought into contact with and rolled into a cylindrical body, and moved to a heat-hardening furnace in a state of being a permeable multi-layered cylindrical body, and is allowed to stand still. The method for producing a substrate for a flexible printed wiring board according to the first aspect of the invention, wherein the thickness of the low thermal expansion polyimine resin layer of the main layer is the total thickness t2 of the thermoplastic polyimide layer of the upper and lower thermoplastic layers. The ratio (h/Q) is in the range of 2 to 100. 3. The method for producing a substrate for a flexible printed wiring board according to claim 1 or 2, wherein the hardening treatment in the heat-hardening furnace is performed under reduced pressure In the case of an inert gas atmosphere, the method for manufacturing a flexible printed wiring board according to claim 1 or 2, wherein the hardening treatment of the heat-hardening furnace is performed by radiant heating And a method for manufacturing a substrate for a flexible printed wiring board according to the first or second aspect of the invention, wherein the heating is performed by a method of heating a conductor on a conductor of a plurality of layers of a cylinder. The heating rate of the hardening furnace is carried out in the range of 0.75 to 12 ° C / min. -twenty one -