JP2005303004A - Method for manufacturing printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of a wiring circuit substrate which can effectively prevent warpage and variation in dimensions even if it is used under high humidity. <P>SOLUTION: A metallic reinforcing plate 1 is prepared, and a varnish 2 comprising polyamic acid and triethylenediamine is cast on the metallic reinforcing plate 1. The varnish 2 is heated and dried at 80 to 150°C, for example, and then it is heated and hardened for about 2 hours at 250 to 500°C, for example. Consequently, an insulating layer 3 is formed. A tape carrier 8 for TAB having such an insulating layer 3 effectively prevents warpage and variation in dimensions even if it is used under high humidity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a printed circuit board, and more particularly to a method for manufacturing a printed circuit board that can be used for manufacturing a TAB tape carrier or the like.

  Polyimides having excellent flexibility and heat resistance are widely used for insulating layers such as flexible printed circuit boards. Such an insulating layer made of polyimide is obtained by curing (imidizing) polyamic acid.

  For example, a substrate for a printed circuit board in which a resin composition for a substrate containing a polyimide resin precursor (polyamic acid) and a tertiary amine compound is applied on a metal foil has been proposed (Patent Document 1). reference.). With this printed circuit board substrate, it is possible to prevent warping and dimensional changes from occurring during formation of the printed circuit pattern.

Further, for example, it has been proposed to imidize a polyamic acid film containing 7 to 30% by weight of a good solvent by immersing it in an immersion liquid containing an acid anhydride and ethers and / or ketones (for example, , See Patent Document 2). In this method, by using an amine catalyst such as triethylenediamine, a polyimide film having a high imidization ratio can be produced at a low temperature while maintaining the shape of the polyamic acid film.
JP 2003-8157 A JP-A-6-9801

  However, the printed circuit board is not only prevented from warping and dimensional change during the formation of the wiring circuit pattern as described above. For example, when mounting an electronic component, the warpage or dimensional change during mounting of the electronic component is not necessary. In particular, it is required to prevent warpage and dimensional change when the printed circuit board is used under high humidity.

  An object of the present invention is to provide a method for manufacturing a printed circuit board that can effectively prevent warpage and dimensional change even when used under high humidity.

  In order to achieve the above object, a method for manufacturing a wired circuit board according to the present invention is a method for manufacturing a wired circuit board including an insulating layer, and the step of forming the insulating layer includes polyamic acid and triethylenediamine. The method includes a step of casting the varnish, and a step of drying the cast varnish, followed by heat-curing subsequent to the drying.

  Moreover, in the manufacturing method of the wired circuit board of this invention, it is suitable that the content rate of the said triethylenediamine is 0.5-5 weight part with respect to 100 weight part of said polyamic acids.

  In the method for producing a printed circuit board according to the present invention, the polyamic acid is obtained by polycondensation of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine. It is preferred that

  The method for manufacturing a printed circuit board according to the present invention further includes a step of preparing a metal reinforcing plate, and in the step of forming the insulating layer, the insulating layer may be formed on the metal reinforcing plate. Is preferred.

  Moreover, it is preferable that the manufacturing method of the printed circuit board of this invention is used in order to manufacture the TAB tape carrier.

  According to the method for manufacturing a printed circuit board of the present invention, in the step of forming the insulating layer, the varnish containing polyamic acid and triethylenediamine is cast and then heated and cured following drying. Thereby, even if it uses under high humidity, generation | occurrence | production of a curvature and a dimensional change can be prevented effectively.

  In the method for producing a printed circuit board according to the present invention, a varnish containing polyamic acid and triethylenediamine is cast, dried, and subsequently heated and cured to form an insulating layer.

  In the method for producing a printed circuit board of the present invention, the polyamic acid is not particularly limited, but usually has a repeating unit structure represented by the following general formula (1), and for example, its weight average molecular weight is about 5000 to 200000. Preferably, the thing of about 10,000-100,000 is mentioned.

(In the formula, R1 represents a tetravalent organic group, and R2 represents a divalent organic group.)
In the above formula (1), examples of the tetravalent organic group represented by R1 include skeletons such as benzene, naphthalene, perylene, diphenyl, diphenyl ether, diphenylsulfone, diphenylpropane, diphenylhexafluoropropane, benzophenone, butane, and cyclobutane. An aromatic, araliphatic, aliphatic, and alicyclic tetravalent organic group having Preferably, a tetravalent organic group having a skeleton of benzene, diphenyl, diphenylhexafluoropropane, or benzophenone is used. Note that these tetravalent organic groups may be of only one type, or may be two or more types.

  In the above formula (1), examples of the divalent organic group represented by R2 include diphenyl ether, benzophenone, diphenylmethane, diphenylpropane, diphenylhexafluoropropane, diphenylsulfoxide, diphenylsulfone, diphenyl, benzene, and diphenoxybenzene. Aromatic, araliphatic, aliphatic, and alicyclic divalent organic groups having a skeleton such as Preferably, a divalent organic group having a skeleton of diphenyl ether, benzene, or diphenoxybenzene is used. In addition, these divalent organic groups may be only one kind, and may be two or more kinds.

  More specifically, such a polyamic acid can be obtained by reacting an organic tetracarboxylic dianhydride with a diamine. Examples of the organic tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, and 2,2-bis (3,4-dicarboxyphenyl). ) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoro Propane dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfonic acid And dianhydrides. Moreover, they may be used independently and may use 2 or more types together.

  Examples of the diamine include paraphenylene diamine (p-phenylene diamine), m-phenylene diamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2-dimethyl-4,4'-. Diaminobiphenyl, 2,2-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 2,2-bis (4-aminophenoxy) Phenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 2,4- Diaminotoluene, 2,6-diaminotoluene, diaminodiphenylmethane, 4,4′-di Examples include amino-2,2-dimethylbiphenyl. Moreover, they may be used independently and may use 2 or more types together.

  Of these organic tetracarboxylic dianhydrides, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable. 3 ', 4,4'-biphenyltetracarboxylic dianhydride is mentioned. Of these diamines, paraphenylenediamine is preferable.

  The polyamic acid is an appropriate organic solvent such as N-methyl-2-pyrrolidone, N, N, in such a ratio that the organic tetracarboxylic dianhydride and diamine are substantially equimolar. -In a polar solvent such as dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoramide, usually varnish (polyamic acid solution) by polycondensation at 0-80 ° C for 1-48 hours You can get it as

  The concentration (solid content concentration) of the polyamic acid in the varnish is, for example, 10 to 25% by weight, preferably 12 to 20% by weight. If the concentration of the polyamic acid is lower than this, a polyamic acid film may not be obtained with a sufficient film thickness after drying. If the concentration is higher than this, unevenness may occur during casting.

  And in the manufacturing method of the wired circuit board of this invention, triethylenediamine (1,4-diazabicyclo [2,2,2] octane) is mix | blended with the varnish obtained by the above.

  The blending ratio (content ratio) of triethylenediamine is, for example, 0.5 to 5 parts by weight, preferably 1 to 4 parts by weight with respect to 100 parts by weight of the polyamic acid. If the blending ratio is less than this, it may not be possible to effectively prevent warping and dimensional changes, while if the blending ratio is more than this, it may not be possible to effectively reduce the humidity expansion coefficient of the polyimide after curing or The heat resistance of polyimide may be reduced.

  Further, such a varnish may be prepared as a photosensitive varnish by, for example, blending a photosensitive agent such as a 1,4-dihydropyrrolidine derivative. If it is prepared as a photosensitive varnish, it can be formed as a predetermined pattern by exposure and development. In addition, it is preferable to mix | blend a photosensitive agent normally in 0.1-1.0 mol with respect to 1 mol of polyamic acids. Further, for example, a photosensitive varnish can be prepared by introducing a functional group having photosensitivity into the skeleton of polyamic acid.

  Furthermore, you may mix | blend an epoxy resin, bisallyl nadic imide, maleimide etc. with such a varnish as needed.

  In the method for manufacturing a printed circuit board according to the present invention, the varnish thus prepared is cast on a base material, then dried, and without being immersed in a dipping solution, followed by drying and heat curing. A step of forming an insulating layer.

  Although it does not specifically limit as a base material, For example, metal foil, a metal plate, etc. are mentioned. The metal foil or metal plate is made of, for example, copper, copper alloy, nickel, nickel alloy, nickel / iron alloy, iron, stainless steel, aluminum, copper-beryllium, phosphor bronze, or the like.

  For casting, a known method such as spin coating or bar coating is used.

  In addition, the drying is not particularly limited as long as the above-described solvent can be diffused. For example, the drying may be performed at 80 to 150 ° C., preferably 90 to 120 ° C.

  Further, the heat curing is not particularly limited as long as the polyamic acid can be imidized. For example, the heat curing may be performed at 250 to 500 ° C., preferably 350 to 450 ° C.

  Thereby, the polyamic acid is imidized, and an insulating layer made of polyimide is formed on the substrate.

  The thickness of the insulating layer is, for example, 3 to 50 μm, preferably 5 to 40 μm.

  A printed circuit board including an insulating layer formed in this way is less likely to warp or change in dimensions even when used under high humidity, and can improve reliability.

  And the manufacturing method of the wired circuit board of this invention is not specifically limited, For example, it can be used for manufacture of the wired circuit board containing insulating layers, such as a flexible printed circuit board, More specifically, it is TAB. It is suitably used for manufacturing a tape carrier for use. In this case, a metal reinforcing plate is used as the base material on which the varnish is cast. The metal reinforcing plate is made of, for example, stainless steel (SUS303, SUS430, etc.), 42 alloy, or the like.

  Next, with reference to FIG. 1, an embodiment of a method for manufacturing a wired circuit board according to the present invention will be described more specifically by taking as an example the case of manufacturing a TAB tape carrier.

  First, as shown to Fig.1 (a), the above-mentioned metal reinforcement board 1 is prepared. The thickness of the metal reinforcing plate 1 is, for example, 5 to 50 μm, or preferably 10 to 30 μm.

  Next, as shown in FIG. 1B, the varnish 2 described above is cast on the metal reinforcing plate 1. For the casting of the varnish 2, for example, the above-described known method using an applicator such as a spin coater or a bar coater is used.

  Next, as shown in FIG. 1C, the cast varnish is heat-dried and subsequently heat-cured. More specifically, the varnish 2 is heated and cured, for example, at 80 to 150 ° C., such as hot air drying, and then heated and cured at, for example, 250 to 500 ° C. for about 2 hours.

  Thereby, polyamic acid is imidized and the insulating layer 3 made of polyimide is formed on the metal reinforcing plate 1.

  The thickness of the insulating layer 3 is 3-50 micrometers, for example, Preferably, it is 5-40 micrometers. If the thickness of the insulating layer 3 is smaller than this, the electrical insulating property may be insufficient, and if the thickness of the insulating layer 3 is larger than this, the flexibility may be lowered.

  If the varnish 2 is prepared as a photosensitive varnish as described above, after casting the varnish shown in FIG. 1 (b), it is irradiated with actinic rays through a photomask, and then heated as necessary. By forming the latent image and developing the latent image, the varnish can be formed as a predetermined pattern. When this is heated and cured, an insulating layer formed in the predetermined pattern is formed on the metal reinforcing plate 1. It is formed.

  In this method, a wiring circuit pattern is formed on the insulating layer 3 by a known method. Hereinafter, the case where the wiring circuit pattern is formed by the additive method will be described. However, the wiring circuit pattern may be formed by the subtractive method.

  That is, in this method, as shown in FIG. 1D, first, a metal thin film 4 as a seed film is formed on the insulating layer 3. For forming the metal thin film 4, a known thin film forming method such as electroless plating or vacuum deposition is used. Preferably, a sputter deposition method is used. Moreover, chromium, nickel, copper, etc. are preferably used for the conductor used as the metal thin film 4. More specifically, for example, a chromium thin film and a copper thin film are sequentially formed on the insulating layer 3 by sputtering deposition. In forming the metal thin film 4, the thickness of the chromium thin film is, for example, 300 to 1000 mm, and the thickness of the copper thin film is, for example, 700 to 1000 mm.

  Next, in this method, as shown in FIG. 1E, a plating resist 5 is formed on the metal thin film 4 formed on the insulating film 3 in an inverted pattern of the wiring circuit pattern.

  The plating resist 5 is formed, for example, as a reverse pattern of the wiring circuit pattern by a known method of laminating a dry film resist on the surface of the metal thin film 4 and exposing and developing.

  Next, in this method, as shown in FIG. 1 (f), the conductor layer 6 is formed in a wiring circuit pattern on the metal thin film 4 exposed from the plating resist 5. As the conductor forming the conductor layer 6, for example, a metal such as copper, nickel, gold, solder, or an alloy thereof is used. Preferably, copper is used. Moreover, although formation of the conductor layer 6 is not specifically limited, Preferably, electrolytic plating is used, More preferably, electrolytic copper plating is used. The thickness of the conductor layer 6 is, for example, 5 to 10 μm, or preferably 6 to 9 μm.

  Thereafter, if necessary, a tin plating layer or the like may be formed on the conductor layer 6 exposed from the plating resist 5.

  Next, in this method, as shown in FIG. 1 (g), the plating resist 5 is removed, and subsequently, as shown in FIG. 1 (h), the portion of the metal thin film 4 on which the plating resist 5 has been formed is removed. Remove. For removing the plating resist 5 and the metal thin film 4, for example, a known etching method such as chemical etching (wet etching) is used.

  In this method, as shown in FIG. 1 (i), a covering layer 7 is formed so as to cover the conductor layer 6, and the metal reinforcing plate 1 is etched into a predetermined pattern, if necessary, for TAB. A tape carrier 8 is obtained. The covering layer 7 is formed by a known method using a solder resist made of a heat resistant resist.

  The covering layer 7 may be formed so as to cover a part of the wiring circuit pattern of the conductor layer 6, or may be formed so as to cover all of the wiring circuit pattern of the conductor layer 6.

  The TAB tape carrier 8 having the insulating layer 3 thus obtained can effectively prevent warpage and dimensional change even when used under high humidity.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples.

Example 1
A stainless steel (SUS430) foil having a thickness of 25 μm was prepared as a metal reinforcing plate (see FIG. 1A).

  Moreover, the varnish was prepared as follows. That is, polyamic acid is obtained by reacting an equimolar amount of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride with paraphenylenediamine in N-methyl-2-pyrrolidone and polycondensation. A varnish consisting of a solution was obtained. The concentration of polyamic acid in the varnish was 18% by weight.

  Next, 0.5 parts by weight of triethylenediamine was added to 100 parts by weight of the polyamic acid, and the resulting varnish was mixed and dissolved.

  This varnish was cast on the above stainless steel foil using an applicator (see FIG. 1 (b)), dried at 100 ° C. for 15 minutes, and further heated at 400 ° C. for 2 hours to have a thickness of 25 μm. An insulating layer made of polyimide was formed (see FIG. 1C).

  Next, a conductor layer (copper wiring) having a predetermined wiring circuit pattern was formed on the insulating layer by an additive method (see FIGS. 1D to 1H).

  Then, the stainless steel foil was etched into a predetermined pattern to obtain a TAB tape carrier.

Example 2
A TAB tape carrier was obtained by the same operation as in Example 1 except that 2 parts by weight of triethylenediamine was added to 100 parts by weight of polyamic acid.

Example 3
A TAB tape carrier was obtained in the same manner as in Example 1 except that 5 parts by weight of triethylenediamine was added to 100 parts by weight of polyamic acid.

Comparative Example 1
A TAB tape carrier was obtained in the same manner as in Example 1 except that 2 parts by weight of imidazole was added to 100 parts by weight of polyamic acid instead of triethylenediamine.

Comparative Example 2
After casting varnish on stainless steel foil and drying at 100 ° C. for 15 minutes, mixed solvent containing diethyl ether, acetic anhydride and pyridine (volume ratio, diethyl ether: acetic anhydride: pyridine = 9: 1: 2) A TAB tape carrier was obtained in the same manner as in Example 1 except that the insulating layer was formed by immersing the substrate in normal temperature for 12 hours and then heating at 200 ° C. for 2 hours.

Evaluation The humidity expansion coefficient and the amount of warpage of each TAB tape carrier obtained in Examples and Comparative Examples were measured.

  The humidity expansion coefficient was measured as a dimensional change rate when the relative humidity was changed from 2% to 95% at a temperature of 30 ° C. for each TAB tape carrier. The dimensions of each TAB tape carrier were measured for a portion without the stainless steel foil and the conductor layer, that is, a portion having only an insulating layer made of polyimide.

  In addition, the amount of warping is as shown in FIG. As shown schematically, each test piece is placed on a horizontal plate and the distances from the surface of the horizontal plate to the four corners on the back of the test piece are measured, and these distances are measured for each test. It was determined by averaging the pieces.

  These results are shown in Table 1.

  In each of Examples 1 to 3, the humidity expansion coefficient was less than 10%, while Comparative Example 1 and Comparative Example 2 showed 10% or more.

  The amount of warpage was 0 mm in each of Examples 1 to 3, whereas 2 mm was shown in Comparative Examples 1 and 2.

It is process drawing which shows one Embodiment of the manufacturing method of the printed circuit board of this invention, Comprising: (a) The process of preparing a metal reinforcement board, (b) The process of casting a varnish on a metal reinforcement board (C) is a step of drying the cast varnish, followed by heat-curing to form an insulating layer, (d) is a step of forming a metal thin film on the insulating layer, (e) ) Is a step of forming a plating resist on the metal thin film with a reversal pattern of the wiring circuit pattern, (f) is a step of forming a conductor layer on the metal thin film exposed from the plating resist with a wiring circuit pattern, (g) is a step of removing the plating resist, (h) is a step of removing the metal thin film where the plating resist was formed, and (i) is a coating layer formed so as to cover the conductor layer. The process to perform is shown. In an Example, it is a schematic explanatory drawing for demonstrating the measuring method of curvature amount.

Explanation of symbols

1 Metal reinforcing plate 2 Varnish 3 Insulating layer 8 Tape carrier for TAB

Claims (5)

A method of manufacturing a printed circuit board including an insulating layer,
The step of forming the insulating layer includes
Production of a printed circuit board comprising a step of casting a varnish containing polyamic acid and triethylenediamine, and a step of drying the cast varnish, followed by heating and curing. Method. 2. The method of manufacturing a printed circuit board according to claim 1, wherein a content ratio of the triethylenediamine is 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyamic acid. The polyamic acid is obtained by polycondensation of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine, according to claim 1 or 2. The manufacturing method of the printed circuit board of description. Furthermore, a process for preparing a metal reinforcing plate is provided,
The method for manufacturing a printed circuit board according to claim 1, wherein the insulating layer is formed on the metal reinforcing plate in the step of forming the insulating layer. The manufacturing method of the printed circuit board in any one of Claims 1-4 used in order to manufacture the tape carrier for TAB.

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