JP2019091858A - Method for manufacturing print wiring board, print wiring board and, photosensitive resin composition used in the manufacturing method - Google Patents

Abstract

To provide a method for manufacturing a print wiring board, which enables the formation of a mountable copper surface by a simpler step and which does not include the step of applying a plating resist.SOLUTION: A method for manufacturing a print wiring board comprises the steps of: forming a coating film 3 of a photosensitive resin composition on a wiring board 1 with a conductor circuit 2; providing, on the coating film 3 of the photosensitive resin composition, an unreacted portion 33, an imperfectly reacted portion 32 and a perfectly reacted portion 31; forming, by developing, a first pad part 51 and an opening for a second pad part 52, having a developing residual film 32A; performing a plating treatment on the first pad part 51; and removing the developing residual film 32A to form the second pad part 52 after the plating treatment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a printed wiring board, a printed wiring board, and a photosensitive resin composition used for the method of manufacturing the same.

  BACKGROUND ART In recent years, information communication terminals convenient for carrying, represented by mobile devices, etc., are favored from lightweight and compact products due to their use. Along with that, the packaging method of the semiconductor electronic component used inside the information communication terminal is also that more compact and high density CSP (chip size package) is used, and in addition, The technical requirements for printed wiring boards when mounting CSPs are also becoming higher.

  Conducting nickel / gold plating on the conductor on the surface of the printed wiring board is necessary for oxidation prevention and key contact points, and in addition, for high density printed wiring boards represented by mobile phones etc., lead wiring An electroless nickel / gold plating process that does not require However, in high density electronic components such as CSP, especially where there is continuity due to solder connection, nickel / gold plating should not be performed, that is, nickel / gold plating only on partially required places. It is desirable to carry out the treatment.

  For example, in Patent Document 1, a circuit wiring is formed in a desired shape, and a thermosetting or ultraviolet curing plating resist is partially applied to a surface layer portion of a printed wiring board coated with a solder resist; A step of curing the plating resist by heating or ultraviolet irradiation, a step of treating nickel / gold plating on a conductor surface of a surface layer portion of the printed wiring board not coated with the plating resist, a step of peeling the plating resist A method of surface treatment of a printed wiring board comprising the above is disclosed together with the effect that a good quality partial nickel / gold plating state can be formed in a short process and manufacturing time and at low cost.

Japanese Patent Application Publication No. 2007-12735

  However, in the method of manufacturing a printed wiring board described in Patent Document 1, the process is complicated because the process of partially applying the plating resist is included.

  Therefore, an object of the present invention is a printed wiring board capable of forming a mountable pad portion not subjected to a plating process and a pad portion subjected to a plating process by a simpler process that does not include the step of applying a plating resist. It is an object of the present invention to provide a photosensitive resin composition used in a method of manufacturing and a method of manufacturing a printed wiring board.

  As a result of intensive investigations by the present inventors, the present inventors formed a coating of a photosensitive resin composition on a wiring substrate, provided an unreacted part, an incompletely reacted part and a completely reacted part in the coated film, A resist film is formed in which the first pad portion and the second pad portion opening are formed, and after plating, the development residual film in the second pad portion opening is removed, and the first pad portion that has been plated is plated It has been found that it is possible to manufacture printed wiring boards each having a second pad portion which is not formed, and the present invention has been completed.

  That is, the method for producing a printed wiring board according to the present invention comprises the steps of forming a coating of a photosensitive resin composition on a wiring substrate having a conductor circuit, an unreacted portion on the coating of the photosensitive resin composition, A step of providing an incomplete reaction portion and a complete reaction portion, a step of forming a first pad portion by development, and a step of forming an opening for a second pad portion having a development residual film, and plating the first pad portion And a step of forming the second pad portion by removing the development residual film after the plating process.

  It is preferable that the manufacturing method of the printed wiring board of this invention is 1 to 50% of the residual film ratio by said development.

  The printed wiring board of the present invention is obtained by the above-mentioned manufacturing method.

  The photosensitive resin composition of this invention is used for the manufacturing method of the said printed wiring board.

  According to the present invention, it is possible to perform the plating process such as the nickel / gold plating only on the partially required pad portion by the simpler process which does not include the process of applying the plating resist. That is, according to the present invention, a method of manufacturing a printed wiring board capable of forming a plated pad portion and a non-plated pad portion can be provided, and a photosensitive resin composition used for the method. Can.

It is explanatory drawing of the process of this invention.

In the method for producing a printed wiring board according to the present invention, a step of forming a coating of a photosensitive resin composition on a wiring substrate having a conductor circuit, and a non-reacted portion or incomplete on the coating of the photosensitive resin composition. A step of providing a reaction portion and a complete reaction portion, a step of forming a first pad portion by development and a step of forming an opening for a second pad portion having a development residual film, and plating the first pad portion And a step of forming the second pad portion by removing the development residual film after the plating process.
Conventionally, a thermosetting or ultraviolet curing plating resist has been partially applied to the surface layer portion of a printed wiring board coated with a solder resist, but in the present invention, a coating film of a photosensitive resin composition is used. Unreacted, incompletely reacted, and completely reacted areas are provided, and the developed residual film formed on the incompletely reacted area after development acts as a plating resist, and after plating, the residual film from the incompletely reacted area is removed Then, a second pad portion not plated is formed. Therefore, the partially plated printed wiring board can be obtained by a simple process without using a plating resist.
In the method for producing a printed wiring board according to the present invention, the unreacted portion, the incompletely reacted portion, and the completely reacted portion are also referred to as an unexposed portion, a semi-exposed portion, and an exposed portion, respectively. The first pad portion is also referred to as a plating formation pad portion.

The photosensitive resin composition of the present invention may be negative or positive, but is preferably negative. If it is a negative type, a development residual film can be easily formed.
Whether the photosensitive resin composition is negative or positive, in the production method of the present invention, after the photosensitive resin composition is applied on the wiring substrate, for example, it is activated by the shade of gray scale of the mask. The exposure amount of the energy ray is adjusted to form a contrast to provide an unreacted portion, an incompletely reacted portion, and a completely reacted portion.
Here, when the photosensitive resin composition used in the production method of the present invention is a negative type, an unreacted portion removed by development and an incompletely reacted portion remaining as a development residual film by development and functioning as a plating resist substitute And a completely reacted portion which remains as a thicker film than the development residual film and can function as a plating resist.
On the other hand, when the photosensitive resin composition used in the production method of the present invention is a positive type, a completely reacted portion removed by development and an incompletely reacted portion remaining as a development residual film by development and functioning as a plating resist substitute And an unreacted portion which remains as a thick film than the development residual film and functions as a plating resist.
After the development, the first pad portion is subjected to a surface treatment including at least plating, and after the plating treatment, the development residual film in the incomplete reaction portion is removed to form a second pad portion having a mountable surface.

  That is, the present invention differs from the prior art described in Patent Document 1 in that the development residual film formed in the opening of the coating film of the composition is used as a substitute for the plating resist. For this reason, the process of apply | coating a plating resist becomes unnecessary and a process becomes simple. By simplifying the process, it is possible to shorten the manufacturing time and reduce the manufacturing cost.

  The advantage of the present invention goes beyond the simplification of the process. In the conventional plating resist, it is attacked by the electroless plating solution and eluted in the electroless plating solution to decompose the electroless plating solution or prevent the plating metal layer from being favorably deposited on the surface of the external connection pad. Although there was a problem, in the present invention, such a plating resist is not formed, so that such a problem can be prevented.

  Below, the manufacturing method of the printed wiring board by this invention is demonstrated, referring FIG. The method for producing a printed wiring board according to the present invention comprises (1) coating film forming step of photosensitive resin composition, (2) drying step, (3) incomplete reaction portion forming step, (4) developing step, (5) Although it is preferable to include a thermosetting process, a photocuring process, (6) a plating process, and (7) a second pad forming process, at least (1) a coating forming process, and (3) an incomplete reaction forming process, And (4) a development step, (6) a plating treatment step, and (7) a second pad portion formation step.

[(1) Coating film formation process of photosensitive resin composition]
In the present invention, a photosensitive resin composition that can function as a plating resist is used. The photosensitive resin composition may be a photosensitive resin composition soluble in an aqueous alkaline solution or a photosensitive resin composition soluble in an organic solvent, but it is a photosensitive resin composition soluble in an aqueous alkaline solution preferable. When the photosensitive resin composition of the present invention is a negative type, it preferably contains an alkali-soluble resin and a photopolymerization initiator. For example, a development-type solder resist PSR-4000 series product manufactured by Solar Ink Mfg. Co., Ltd. is suitably used. be able to. On the other hand, when the photosensitive resin composition of the present invention is a positive type, a composition containing an alkali-soluble resin and a photoacid generator such as diazonaphthoquinone can be used.

Hereinafter, the manufacturing method of the printed wiring board using the negative photosensitive resin composition of this invention is demonstrated, referring FIG.1 (A)-(E).
First, as shown in FIG. 1A, a photosensitive resin composition is applied onto a wiring substrate 1 having a conductor circuit 2 to form a coating film 3. As the coating method of the photosensitive resin composition, all known ink coating methods such as screen printing method, spray coating method, roll coating method, immersion method, spin coating method and curtain coating method can be used. The material of the conductor circuit may be any conductive material such as copper, silver, gold or the like.

The film thickness of the coating film 3 is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less. When the thickness is 5 μm or more and 50 μm or less, the development residual film 32A that can be easily removed in the step of forming the second pad portion can be easily formed in the incomplete reaction portion 32.
The coating 3 of the photosensitive resin composition may be at least one that can function as a plating resist, but is preferably one that can also function as a solder resist.

[(2) Drying process]
Subsequently, the coating film 3 is dried if necessary. In order to volatilize the organic solvent in the photosensitive resin composition, the coating film 3 of the photosensitive resin composition is dried, for example, by performing preliminary drying at a temperature in the range of 60 to 100 ° C.

  In forming the coating film 3 on the wiring substrate 1, the photosensitive resin composition is applied to a suitable support in advance and then dried to form the coating film 3 (resin layer of dry film). The resin layer of the dry film may be transferred to the wiring substrate 1 by applying pressure to the dry film and the wiring substrate 1 after overlapping the resin layer of the dry film on the wiring substrate 1 (dry film method). In this case, the drying step may be omitted.

[(3) Incomplete reaction part formation process]
Subsequently, as shown in FIG. 1B, the coating film 3 is pattern-exposed by irradiating the coating film 3 with an active energy ray through the mask 4.

  The active energy ray for exposure is selected so that the curing reaction of the photosensitive resin composition proceeds upon irradiation with the active energy ray. As the active energy ray for exposure, for example, ultraviolet light, visible light or near infrared light is selected. When ultraviolet light is selected, the ultraviolet light source is selected from, for example, chemical lamps, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, xenon lamps and metal halide lamps.

  The mask 4 includes three types of portions having different degrees of light transmittance. The mask 4 has, for example, a portion having light transmittance (hereinafter referred to as a light transmitting portion 41) and a portion having light transmittance lower than the light transmitting portion 41 (hereinafter referred to as a semitransparent portion 42) by gray scale shading. And a non-light transmitting portion (hereinafter referred to as non-transmitting portion 43).

  When the coating film 3 is pattern-exposed through the mask 4, active energy rays are irradiated to a portion (exposure portion) corresponding to the transmissive portion 41 in the coating film 3, and the complete reaction portion 31 is provided. An active energy ray is irradiated to the portion (semi-exposed portion) corresponding to the semi-transmissive portion 42 in the coating film 3 with an exposure amount lower than that of the exposed portion, and the incompletely reacted portion 32 is provided. In the part (unexposed part) corresponding to the non-permeable part 43 in the coating film 3, the active energy ray is not irradiated, and the unreacted part 33 is provided. That is, the complete reaction part 31 is a part to which the active energy ray is irradiated at the time of exposure, and the incomplete reaction part 32 is a part to which the active energy ray is irradiated at a lower exposure amount than the complete reaction part 31 at the irradiation of the active energy ray. The non-reacted portion 33 is a portion which is not irradiated with active energy rays at the time of exposure. By designing the mask 4 so that the complete reaction part 31, the incomplete reaction part 32, and the unreacted part 33 are located at predetermined positions in the coating film 3, the amount of active energy ray irradiation to the photosensitive resin composition is obtained. Can be adjusted.

  When the coating film 3 is exposed in this manner, the curing reaction of the photosensitive resin composition proceeds in the complete reaction portion 31 of the coating film 3 and the photoreaction rate in the incomplete reaction portion 32 is lower than that in the complete reaction portion 31. The curing reaction of the photosensitive resin composition proceeds. On the other hand, in the unreacted portion 33, the curing reaction of the photosensitive resin composition does not proceed.

  In order to control the exposure amount in the complete reaction area 31, the incomplete reaction area 32, and the unreacted area 33 to a desired value, the mask 4 is provided with three types of portions having different degrees of light transmittance as described above. You do not have to. For example, first, the coating film 3 is irradiated with active energy rays through a mask (first mask) that shields the unreacted portion 33 and does not shield the complete reaction portion 31 and the incomplete reaction portion 32, and A mask (second mask) covering the incomplete reaction part 32 and the complete reaction part 31 is superimposed on one mask, and the active energy ray is further transmitted through the first mask and the second mask. It may be irradiated. Even in this case, the complete reaction portion 31 is irradiated with the active energy ray, and the incomplete reaction portion 32 is irradiated with the active energy ray at a lower exposure amount than the complete reaction portion 31, and the unreacted portion 33 is activated. It means that energy rays are not irradiated.

  Further, the mask 4 may not be used in order to control the exposure amount in the complete reaction area 31, the incomplete reaction area 32, and the unreacted area 33 to a desired value. For example, the exposure wavelength may be changed in each of the complete reaction area 31, the incomplete reaction area 32, and the unreacted area 33. Alternatively, direct imaging (DI) may be used in which the exposure amount of each of the completely reacted portion 31, the incompletely reacted portion 32, and the unreacted portion 33 on the coating film 3 is adjusted by a program.

  It is preferable to irradiate an active energy ray so that the photoreaction rate of the composition in the complete reaction part 31 is 50% or more, and more preferably 60% or more. The coating film 3 which is not removed in the developing step and the second pad portion forming step can be favorably formed on the completely reacted portion 31 as it is 50% or more.

It is preferable to irradiate an active energy ray so that the photoreaction rate of the composition in the incomplete reaction part 32 is 1% or more and less than 50%, and more preferably 5% or more and 30% or less. When the content is 1% or more and less than 50%, the development residual film 32A that can be easily removed in the second pad formation step can be easily formed in the incomplete reaction part 32.
The residual film ratio is preferably 1% or more and less than 50%, and more preferably 5% or more and 30% or less. The residual film rate (%) can be calculated by 100 × (thickness of residual film after development / thickness of coating before development), and the thickness of residual film after development is the entire surface of the second pad portion 52. Means the thickness in the state of covering the

[(4) Development step]
After the complete reaction area 31, the incomplete reaction area 32, and the unreacted area 33 are provided, the coating film 3 is developed with a developer. In the development step, it is preferable to develop with an alkaline developer, but it may be developed with an organic solvent. The coating 3 after development is shown in FIG. 1 (C). Unreacted portion 33 of coating film 3 is removed from above wiring substrate 1 to form first pad portion 51, while completely reacted portion 31 and incompletely reacted portion 32 of coating film 3 remain on wiring substrate 1. . That is, the non-reacted portion 33 is removed by development to form the first pad portion 51 for plating, while in the incompletely reacted portion 32, an opening having the development residual film 32A is formed by development, and the development residual film 32A Functions as a plating resist, and the complete reaction portion 31 remains as a thicker film than the development residual film 32A in development and functions as a plating resist.

  Specific examples of the alkaline developer include sodium carbonate aqueous solution, potassium carbonate aqueous solution, ammonium carbonate aqueous solution, sodium hydrogencarbonate aqueous solution, potassium hydrogencarbonate aqueous solution, ammonium hydrogencarbonate aqueous solution, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonium hydroxide aqueous solution, Examples include aqueous tetramethyl ammonium hydroxide and aqueous lithium hydroxide. As the developer, organic amines such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine and the like can also be used. The solvent in the alkaline developer may be water alone or a mixture of water and a hydrophilic organic solvent such as lower alcohols.

  The film thickness of the incompletely reacted portion 32 after the development step, that is, the development residual film 32A is preferably 0.1 μm to 4 μm, and particularly preferably 0.2 μm to 2 μm. By being 0.1 micrometer or more and 4 micrometers or less, while becoming easy to remove by a 2nd pad part formation process, it functions well also as a plating resist.

[(5) heat curing, light curing process]
The coating film 3 after the development treatment is subjected to either a heat curing treatment or a light curing treatment, as necessary. The heat curing treatment and the light curing treatment may be any conditions that can withstand the later plating treatment.

  After heating the complete reaction area 31 and the development residual film 32A, the whole of the complete reaction area 31 and the development residual film 32A may be irradiated with active energy rays. In this case, the curing reaction of the photosensitive resin composition remaining unreacted in the completely reacted portion 31 and the development residual film 32A proceeds. In addition, a thermosetting process may be performed after a photocuring process, and you may process each in multiple times.

[(6) plating process]
Next, as shown in FIG. 1D, the first pad portion 51 is subjected to a surface treatment including at least plating 6 such as a nickel / gold plating treatment. As the plating treatment here, any of tin plating treatment, OSP treatment and the like can be used besides nickel / gold plating treatment. Among these, as the nickel / gold plating process, any of electroless nickel / gold plating process and electrolytic nickel / gold plating process can be used, but in particular, plating process on high density wiring board used for mobile phones, smartphones, etc. In the process, from the viewpoint of reliability, electroless nickel / gold plating is preferably used.

  The electroless nickel / gold plating process is performed, for example, under the following conditions. First, for the purpose of mainly cleaning the wiring substrate 1 having the coating film 3, degreasing, water washing, acid washing, soft etching and water washing are sequentially performed. Next, the catalyst is treated on the surface, and then put into a bath of a nickel plating solution at 90 ° C. to deposit about 5 μm of electroless nickel plating at a plating rate of 3 to 5 minutes per 1 μm. Then, after washing with water, it is poured into a bath of a gold plating solution at 90 ° C., and electroless gold plating of about 0.03 μm is attached at a plating rate of 3 to 5 minutes.

  Since the plating process is carried out at a plating temperature of 90 ° C., in the prior art, the plating resist elutes, causing problems such as contamination of the plating solution, and additionally, the surface of the wiring substrate is treated with the contaminated plating solution. While the quality of the nickel / gold plating used is poor and it has been difficult to obtain a good printed wiring board, in the present invention, since the plating resist is not used, the plating solution is not contaminated.

[(7) Second Pad Forming Step]
Next, as shown in FIG. 1E, the development residual film 32A is removed to form a second pad portion 52. As shown in FIG. 1E, after the removal process of the development residual film 32A, a second pad portion 52 having a mountable surface is formed. Removal processing of the development residual film 32A includes chemical treatment using acid, alkali, solvent, etc., physical treatment using laser, plasma, etc. Specifically, for example, a method using sodium hydroxide aqueous solution etc. of about 5% is used. is there.

Further, it is desirable to further perform a solder surface treatment such as a water-soluble preflux treatment or a solder leveler on the second pad portion 52 on which the mountable surface is formed in order to protect the surface of the component mounting pad from oxidation.
In FIG. 1, the widths of the first pad opening and the second pad opening are narrower than the width of the conductor circuit, but may be wider.

  EXAMPLES The present invention will be specifically described with reference to examples but the present invention is not limited to the following examples.

A solder resist PSR-4000 EG30 for developing type spray coating, manufactured by Solar Ink Mfg. Co., Ltd., was coated on the entire surface of the patterned copper foil substrate (wiring substrate) by screen printing, and dried at 80 ° C. for 20 minutes. The film thickness of this dried coating film was 20 μm. Then, a photomask was applied to this substrate with a light transmittance of 50% to the incompletely reacted portion and a light transmittance of 100% to the completely reacted portion, and pattern exposure was performed with ultraviolet light at an exposure amount of 600 mJ / cm ² . The photoreaction rate of the composition of the complete reaction part was 70%, and the photoreaction rate of the composition in the incomplete reaction part was 30%. In addition, FT-IR by Perkin-Elmer company was used for the measurement of a photoreaction rate.
Thereafter, development was performed with a 1% by mass aqueous solution of sodium carbonate at a spray pressure of 1.5 kg / cm ² to form a resist pattern in which a first pad portion and an opening for a second pad portion having a development residual film were formed. Here, the development residual film was 1 μm, and the residual film ratio was 5%. Then, the substrate was heated in a closed oven under heat curing conditions of 150 ° C. × 60 minutes.

The test substrate prepared as described above is degreased by immersion for 3 minutes in an acidic degreasing solution (Meteix L-5B, 20% by volume aqueous solution manufactured by Nippon McDarmid Co., Ltd.) at 30 ° C. for 3 minutes in flowing water. It was immersed and washed with water. Next, the test substrate was immersed in a 14.3% by mass aqueous solution of ammonium persulfate for 3 minutes at room temperature for soft etching, and then immersed in running water for 3 minutes and washed with water. The test substrate was immersed in a 10% by volume aqueous sulfuric acid solution at room temperature for 1 minute, and then immersed in running water for 30 seconds to 1 minute to wash with water. Next, the test substrate is immersed for 7 minutes in a 30 ° C. catalyst solution (Meltex Co., Ltd., 10% by volume aqueous solution of metal plate activator 350), catalyst is applied, and then immersed in flowing water for 3 minutes. It was washed with water. The test substrate on which the catalyst was applied was immersed in a nickel plating solution at 85 ° C. (Meltex Co., Ltd., 20% by volume aqueous solution of Melplate Ni-865M, pH 4.6) for 20 minutes to perform electroless nickel plating. went. The test substrate was immersed in a 10% by volume aqueous sulfuric acid solution at room temperature for 1 minute, and then immersed in running water for 30 seconds to 1 minute to wash with water. Next, the test substrate is immersed in a 95 ° C. gold plating solution (made by Meltex Co., Ltd., an aqueous solution of 15% by volume of Auuro Lectrores UP and 3% by volume of gold potassium cyanide, pH 6) for 10 minutes for electroless gold plating. After carrying out, it was immersed in running water for 3 minutes, washed with water, and immersed in warm water of 60 ° C. for 3 minutes and washed with hot water. After sufficient washing with water, the water was thoroughly drained and dried to obtain a test substrate electroless gold-plated on the copper pad portion at a position corresponding to the opening.
Thereafter, the development residual film is removed with a peeling solution of sodium hydroxide aqueous solution (3% by mass, liquid temperature 50 ° C.), and a mountable copper pad portion plated and a copper pad portion not plated are provided. I got a printed circuit board.

  As described above, according to the method for producing a printed wiring board of the present invention, a copper pad portion to which an undercoating treatment including gold plating is applied by a simpler process without using a plating resist, and an undercoating including gold plating It can be seen that a printed wiring board can be manufactured that has an untreated copper pad portion.

DESCRIPTION OF SYMBOLS 1 wiring board 2 conductor circuit 3 coating film 31 complete reaction part 32 incomplete reaction part 32 A development residual film 33 unreacted part 4 mask 41 transparent part 42 semi-transparent part 43 non-transparent part 51 first pad part 52 second Pad part 6 plating

Claims (4)

Forming a coating of a photosensitive resin composition on a wiring substrate having a conductor circuit;
Providing an unreacted portion, an incompletely reacted portion and a completely reacted portion on the coating of the photosensitive resin composition,
A step of forming a first pad portion by development and forming an opening for a second pad portion having a development residual film;
Plating the first pad portion;
After the plating process, removing the development residual film to form the second pad portion;
A method of manufacturing a printed wiring board, comprising:   The method for manufacturing a printed wiring board according to claim 1, wherein a residual film ratio by the development is 1% or more and less than 50%.   The printed wiring board obtained by the manufacturing method of Claim 1 or 2. The photosensitive resin composition used for the manufacturing method of the printed wiring board of Claim 1 or 2.