JP2021197427A - Solder resist layer thinning device - Google Patents

Abstract

To provide a solder resist layer thinning device that prevents a solder resist layer that cannot be completely removed by a micellar removing liquid from remaining and is thinned, and in which a thinning surface is smoothed even when a solder resist layer having an extremely slow micellar dissolution/removal rate is thinned.SOLUTION: A solder resist layer thinning device including a thinning treatment unit for micellarizing components of a solder resist layer that has not been cured by the thinning treatment liquid and a micellar removal treatment unit for removing micelles with the micellar removing liquid removes micelles. The processing unit has a spray nozzle for supplying a micellar removing liquid, and the spray nozzle for supplying the micellar removing liquid is a fixed type and is arranged so that the injection directions are the same. The solder resist layer thinning device is characterized by a fan-shaped spray pattern.SELECTED DRAWING: Figure 9

Description

The present invention relates to a thinning apparatus for a solder resist layer.

In order to prevent solder from adhering to the conductor wiring that does not require soldering on the circuit board, the wiring board inside various electrical devices has a solder resist pattern so that this soldering-free part is covered with a solder resist layer. It is formed. In addition, the solder resist pattern plays a role of preventing oxidation of conductor wiring, electrical insulation, and protection from the external environment.

In a semiconductor package in which electronic components such as semiconductor chips are mounted on a circuit board, mounting the electronic components by flip-chip connection is an effective means for realizing high speed and high density. In the flip chip connection, a part of the conductor wiring is formed as a connection pad for flip chip connection, for example, a solder bump arranged on the connection pad and an electrode terminal of the semiconductor chip are joined.

A photolithography method is generally known as a method for forming a solder resist pattern on a circuit board. In the photolithography method, a solder resist layer 53 is formed on a circuit board having a connection pad 54 and a conductor wiring 52 on the insulating layer 51, and then exposed and developed to remove the solder resist layer 53 around the connection pad 54. By providing the openings, the Solder Mask Defined (SMD) structure shown in FIG. 1 and the Non Solder Mask Defined (NSMD) structure shown in FIG. 2 are formed.

In the SMD structure, since the vicinity of the connection pad 54 is covered with the solder resist layer 53, the exposed surface of the connection pad 54 is required to electrically and reliably connect the electrode terminal of the electronic component and the connection pad 54. It is necessary to secure a necessary amount of solder for the joint portion to be formed, and there is a problem that the connection pad 54 becomes large. Further, in order to ensure that the vicinity of the periphery of the connection pad 54 is covered by the solder resist layer 53, the width of the portion covered by the solder resist layer 53 of the connection pad 54 is secured widely in consideration of processing accuracy. It is necessary to keep it, and there is a problem that the connection pad 54 becomes larger. On the other hand, in the connection pad 54 having an NSMD structure, since the entire connection pad 54 is exposed from the solder resist layer 53, the connection area with the solder is large, and the connection pad 54 is downsized as compared with the case of the SMD structure. Can be done. However, in the NSMD structure, since the connection pad 54 is completely exposed from the solder resist layer 53, an electrical short circuit due to solder may occur between the connection pads 54 adjacent to each other.

In order to solve such a problem, the process of forming the solder resist layer 53 on the circuit board having the connection pad 54, the solder resist layer 53 is not cured until the thickness of the solder resist layer 53 is equal to or less than the thickness of the connection pad 54. A method for forming a solder resist pattern including at least a step of thinning the solder resist layer 53 in this order is disclosed (see, for example, Patent Documents 1 to 4). In this forming method, as shown in FIG. 3, the surface of the connection pad 54 is exposed from the solder resist layer 53, but a structure is obtained in which a part of the side surface of the connection pad 54 is covered with the solder resist layer 53. .. In the structure shown in FIG. 3, it is difficult for an electrical short circuit to occur due to soldering between the connection pads 54 adjacent to each other, and the amount of solder required to electrically and reliably connect the electrode terminals of the electronic components and the connection pads 54 is required. It can be secured, the connection pad 54 can be miniaturized, and a wiring board with high-density wiring having excellent electrical connection reliability can be manufactured.

Further, in Patent Document 5, the substrate on which the resist layer is formed is immersed (dip, dip) in a high-concentration alkaline aqueous solution (thinning treatment liquid) to temporarily insolubilize the micelles of the components of the resist layer in the treatment liquid. A thin-film treatment unit that makes it difficult to dissolve and diffuse, a micelle removal treatment unit that dissolves and removes micelles at once by spraying a micelle removal liquid, a water washing treatment unit that cleans the surface with a water washing treatment liquid, and a drying treatment unit that removes the water washing treatment liquid. A thinning apparatus for a resist layer containing at least four processing units is disclosed.

A part of the resist layer thinning apparatus will be described with reference to the schematic cross-sectional view shown in FIG. In the thin film processing unit 11, the substrate 3 on which the resist layer is formed is charged from the charging port 7. The substrate 3 is transported in a state of being immersed in the thinning treatment liquid 1 in the dip tank 2 by four pairs of transport rolls, and the resist layer is thinned. After that, the substrate 3 is transferred to the micelle removal processing unit 12. In the micelle removal processing unit 12, the micelle removal liquid spray 22 is supplied from the micelle removal liquid supply spray nozzle 21 to the substrate 3 conveyed by the transport rolls 4 pairs through the micelle removal liquid supply pipe 20. In the dip tank 2 inside the thinning treatment unit 11, the resist layer on the substrate 3 is once subjected to the thinning treatment liquid 1 which is a high-concentration alkaline aqueous solution, so that the micelles of the components of the resist layer are once with respect to the thinning treatment liquid 1. It is insolubilized. After that, the resist layer is thinned by removing the micelles by the micelle removing liquid spray 22. Patent Document 5 describes that "the removal of micelles is important to be carried out at once by the micelle removing liquid spray 22 and is preferably carried out promptly under the conditions of water pressure and flow rate of a certain level or higher".

In various conventional liquid treatment devices, as a liquid supply method using a spray, a method of injecting liquid from a fixed or swing type spray nozzle perpendicular to the surface of the substrate, or a method of injecting liquid by a swing type spray nozzle is used for the substrate. A method of spraying a liquid while constantly changing the arrival angle of the liquid on the surface is common. In these conventional liquid supply methods, the liquid flow on the substrate tends to be slow and non-uniform. Therefore, when the micelle removal treatment is performed by these liquid supply methods, the micelle removal may be non-uniform, and the thinning treatment amount of the resist layer may be non-uniform.

Further, in Patent Document 6, the spray nozzle is tilted in the width direction perpendicular to the substrate transport direction, and the tilt angle is in the range of 30 to 70 degrees, so that the liquid flow of the micelle removing liquid on the substrate is prevented. An improved thinning method is disclosed. However, although Patent Document 6 describes the tilt angle of the spray nozzle, it does not describe the direction of the spray nozzle. Therefore, simply adjusting the angle may cause a flow of micellar removing liquid orthogonal to the substrate transport direction to the right and left, and the liquid flow of the micellar removing liquid on the substrate is still slow and non-uniform. In some cases, the amount of thinning of the resist layer becomes non-uniform.

In order to solve such a problem, Patent Document 7 can solve the problem that the thinning amount of the resist layer becomes non-uniform in the substrate surface by tilting the direction of the spray nozzle only in one direction. A device for thinning a resist layer is disclosed. In Patent Document 7, it is proposed to incline a fixed spray nozzle to spray in order to create a unidirectional liquid flow, but in order to spray the spray evenly and uniformly, it can be sprayed over a wide range. There is a statement that it is preferable to use an evenly distributed filled cone type nozzle. However, when the solder resist layer whose dissolution and removal rate of micelles is extremely slow is thinned, the solder resist layer that could not be completely removed by the micelle removing liquid remains, and the solder resist layer after thinning has a portion having a different thickness. In some cases, the thinned surface was not smooth.

In this way, if the solder resist layer that could not be completely removed remains, and the solder resist layer after thinning has parts with different thicknesses and the thinned surface is not smooth, it causes a decrease in weather resistance and yield in production. There was a problem that it led to a decrease in.

Japanese Unexamined Patent Publication No. 2011-192692 International Publication No. 2012/043201 Pamphlet JP-A-2017-107144 Japanese Unexamined Patent Publication No. 2017-103444 Japanese Unexamined Patent Publication No. 2012-27299 Japanese Unexamined Patent Publication No. 2012-59755 Utility Model Registration No. 3207408 Gazette

The problem of the present invention is that even when a solder resist layer having an extremely slow dissolution and removal rate of micelles is thinned in a solder resist layer thinning apparatus, no solder resist layer that cannot be completely removed by the micelle removing liquid remains. It is an object of the present invention to provide a thinning apparatus for a solder resist layer, which makes a thinned surface smooth.

The present inventors have found that these problems can be solved by the following.

(1) Thinning of a solder resist layer including a thinning treatment unit for micellarizing components of a solder resist layer that has not been cured by the thinning treatment liquid and a micellar removing treatment unit for removing micelles with a micellar removing liquid. In the device
The micelle removal processing unit has a spray nozzle for supplying a micelle removal liquid, and the micelle removal processing unit has a spray nozzle for supplying the micelle removal liquid.
The spray nozzle for supplying the micellar remover is a fixed type and is arranged so that the injection directions are the same.
A solder resist layer thinning device characterized in that the spray pattern of the spray nozzle for supplying the micellar remover is fan-shaped.

(2) The solder resist layer thinning device according to (1) above, wherein the spray nozzle for supplying the micellar removing liquid is arranged so that the spray patterns are arranged in a straight line in the direction perpendicular to the transport direction.

According to the present invention, even when the solder resist layer having an extremely slow dissolution and removal rate of micelles is thinned in the solder resist layer thinning apparatus, no solder resist layer that cannot be completely removed by the micelle removing liquid remains. It is possible to provide a thinning apparatus for a solder resist layer in which a thinning surface becomes smooth.

It is explanatory drawing which shows the cross-sectional structure (SMD structure) of a solder resist pattern. It is explanatory drawing which shows the cross-sectional structure (NSMD structure) of a solder resist pattern. It is explanatory drawing which shows an example of the cross-sectional structure of the solder resist pattern formed by using the thinning apparatus of the solder resist layer of this invention. It is a schematic sectional drawing which shows a part of the thinning apparatus of a solder resist layer. It is a schematic diagram which shows an example of the thinning apparatus of the solder resist layer of this invention. It is a schematic diagram which shows an example of the thinning apparatus of the solder resist layer of this invention. It is a schematic diagram which shows an example of the thinning apparatus of the solder resist layer of this invention. It is a schematic diagram which shows an example of the thinning apparatus of the solder resist layer of this invention. It is a schematic diagram which shows the arrangement example of the spray nozzle for supply of a micelle removing liquid in the solder resist layer thinning apparatus of this invention. It is a schematic diagram which shows an example of the thin film | thinning apparatus of the solder resist layer outside the present invention. It is a schematic diagram which shows the spray pattern of the micelle removal liquid in the solder resist layer thinning apparatus.

<Thin filming process>
The thinning step of the solder resist layer by the thinning treatment liquid according to the present invention is a thinning treatment in which the components of the solder resist layer are made into micelles by the thinning treatment liquid and temporarily insolubilized to make it difficult to dissolve and diffuse in the treatment liquid. This is a step including a micelle removal treatment for dissolving and removing micelles at once by spraying a micelle removing liquid. Further, it may include a water washing treatment for washing away the surface of the solder resist layer that could not be completely removed, the thinning treatment liquid remaining and adhering, and the micelle removing liquid with a water washing treatment liquid, and a drying treatment for removing the water washing treatment liquid.

<Thin film processing>
The thinning treatment with the thinning treatment liquid may be performed by a method such as paddle treatment, spray treatment, brushing, scraping, etc., but is preferably performed by a dipping treatment. In the dipping treatment, the substrate on which the solder resist layer is formed is dipped (dip, dip) in the thinning treatment liquid. In the treatment method other than the dipping treatment, bubbles are likely to be generated in the alkaline aqueous solution, and the generated bubbles may adhere to the surface of the solder resist layer during the thinning treatment, resulting in non-uniform film thickness. When using a spray process, the spray pressure should be as low as possible to avoid the formation of air bubbles.

In the present invention, the thickness of the solder resist layer after the formation of the solder resist layer and the amount of the thinned solder resist layer determine the thickness of the solder resist layer after the thinning of the solder resist layer. Further, in the present invention, the amount of thinning of the solder resist layer can be freely adjusted in the range of 0.01 to 500 μm.

<Solder resist>
As the solder resist, an alkali-developed solder resist can be used. Further, it may be a liquid resist or a dry film resist. In the case of a liquid resist, it may be one-component or two-component. Any solder resist that can be thinned with a high-concentration alkaline aqueous solution (thinning treatment liquid) and can be developed with a developing solution having a lower concentration than the thinning treatment liquid can be used. The alkali-developed solder resist contains a photocrosslinkable resin component. The photocrosslinkable resin component contains, for example, at least one selected from an alkali-soluble resin and a photopolymerizable compound, and may further contain a photopolymerization initiator, a thermosetting agent, a filler, and the like. good.

Examples of the alkali-soluble resin include organic polymers such as acrylic resin, methacrylic resin, styrene resin, epoxy resin, amide resin, amide epoxy resin, alkyd resin, and phenol resin, which are ethylenic. It is preferably obtained by polymerizing a monomer having an unsaturated double bond (polymerizable monomer) (radical polymerization or the like). These alkali-soluble resins are composed of a polymer containing a carboxyl group in the molecule and a polymer containing a carboxyl group further having an ethylenically unsaturated double bond in the molecule, and a large number of them are formed in the side chain of the main chain. Since it has a free carboxyl group, it can be developed with a dilute alkaline aqueous solution. In addition, the solder resist layer after cross-linking with the photopolymerizable compound and cured has resistance to an alkaline aqueous solution. These carboxyl group-containing polymers may be used alone or in combination of two or more.

Examples of the monomer having an ethylenically unsaturated double bond include styrene, vinyltoluene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, p-ethoxystyrene and p-. Styrene derivatives such as chlorostyrene and p-bromostyrene; acrylamide such as diacetoneacrylamide; acrylonitrile; vinyl ethers such as vinyl-n-butyl ether; (meth) acrylic acid alkyl ester, (meth) acrylic acid tetrahydrofurfuryl ester, ( Meta) Acrylic acid dimethylaminoethyl ester, (meth) acrylic acid diethylaminoethyl ester, (meth) acrylic acid glycidyl ester, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoro (Β (meth) acrylate, (meth) acrylic acid, α-bromo (meth) acrylic acid, α-chlor (meth) acrylic acid, β-frill (meth) acrylic acid, β-styryl (meth) acrylic acid, etc. Meta) Acrylic acid-based monomer; Maleic acid-based monomer such as maleic acid, maleic acid anhydride, monomethyl maleate, monoethyl maleate, monoisopropyl maleate; fumaric acid, silicic acid, α-cyanosilicic acid , Itaconic acid, crotonic acid, propiolic acid and the like.

Examples of the photopolymerizable compound include a compound obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid; a bisphenol A-based (meth) acrylate compound; and an α, β-unsaturated carboxylic compound containing a glycidyl group. Compounds obtained by reacting with an acid; Urethane monomers such as (meth) acrylate compounds having a urethane bond in the molecule; Nonylphenoxypolyethyleneoxyacrylate; γ-Chloro-β-hydroxypropyl-β'-(meth) acryloyloxyethyl Phthrate compounds such as -o-phthalate, β-hydroxyalkyl-β'-(meth) acryloyloxyalkyl-o-phthalate; (meth) acrylic acid alkyl ester, ethylene glycol, propylene glycol modified nonylphenyl (meth) acrylate And so on. Here, ethylene glycol and propylene glycol represent ethylene oxide and propylene oxide, the ethylene glycol-modified compound has a block structure of an ethylene oxide group, and the propylene glycol-modified compound has a propylene oxide group. It has a block structure. These photopolymerizable compounds may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include benzophenone, N, N, N', N'-tetramethyl-4,4'-diaminobenzophenone (Michler ketone), N, N, N', N'-tetraethyl-4, 4'-Diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2-methyl-1- [4-( Methylthio) Phenyl] -2-morpholino-1-Propanone and other aromatic ketones; 2-ethylanthraquinone, phenanthrenquinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone , 2-Phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, 2, 3-Chinones such as dimethylanthraquinone; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether and benzoin phenyl ether; benzoin compounds such as benzoin, methyl benzoin and ethyl benzoin; benzyl derivatives such as benzyl dimethyl ketal; 2- (o) -Chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-bis (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenyl 2,4,5- Triarylimidazole dimer; aclysine derivatives such as 9-phenylaclydin, 1,7-bis (9,9'-acrydinyl) heptane; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4) Arylphosphine oxide compounds such as 6-trimethylbenzoyl) phenylphosphine oxide; 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], etanone 1- [9- Oxyme esters such as ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl] -1- (O-acetyloxime); oxyphenylacetic acid, Oxyphenylacetic acid esters such as 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester, oxyphenylacetic acid 2- (2-hydroxyethoxy) ethyl ester; bis (η5-2,4-cyclopentadiene-1-yl) )-Bis (2,6-difluoro-3- (1H-pyrrole-1-yl) phenyl) titanosen compounds such as titanium; N-phenylglycine, N-phenylglycine derivatives, coumarin compounds, etc. may be mentioned. Substituents of the aryl groups of the two 2,4,5-triarylimidazoles in the 2,4,5-triarylimidazole dimer may or may not give the same and symmetric compound. Asymmetric compounds may be given. Further, a thioxanthone-based compound and a tertiary amine compound may be combined, such as a combination of diethyl thioxanthone and dimethylaminobenzoic acid. These may be used alone or in combination of two or more.

In order to increase the physical strength of the solder resist layer and the like, a thermosetting component can be contained as a curing agent, if necessary. As such a thermosetting component, an amino resin such as a melamine resin or a benzoguanamine resin, a blocked isocyanate compound, a cyclocarbonate compound, a polyfunctional epoxy compound, a polyfunctional oxetane compound, an episulfide resin and the like can be used, and carboxyl of the alkali-soluble resin can be used. It reacts (crosslinks) with the group and improves heat resistance and chemical resistance.

As the filler, an inorganic or organic filler can be used. In particular, barium sulfate, spherical silica and talc are preferably used, and these can be used alone or in combination of two or more. The average particle size of the filler is preferably in the range of 0.1 to 20 μm. The average particle size is more preferably 0.2 μm or more, more preferably 4 μm or less, still more preferably 2 μm or less.

Any method may be used for forming the solder resist layer on the surface of the substrate. For example, in the case of liquid resist, screen printing method, roll coating method, spray method, dipping method, curtain coating method, bar coating method, air knife method, hot melt method, gravure coating method, brush coating method, offset printing method and the like can be mentioned. Be done. In the case of a dry film resist, a laminating method, a vacuum laminating method and the like can be mentioned.

Examples of the substrate include a flexible substrate and a rigid substrate. The flexible substrate is a laminated substrate in which polyimide, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polymer or the like is used for the insulating layer, and a metal layer is provided on one side or both sides of the insulating layer, and the flexible substrate has high flexibility. The rigid substrate is a laminated substrate in which an insulating substrate in which a glass cloth is impregnated with a thermosetting resin such as a bismaleimide triazine resin or an epoxy resin is laminated on an insulating layer to form an insulating layer, and a metal layer is provided on one or both sides thereof. Can be mentioned. Another example is a multi-layer board manufactured by laminating an insulating material for build-up called a prepreg after processing an inner layer wiring pattern. As the material of the metal layer, any metal such as copper, aluminum, silver, nickel, chromium, gold, or an alloy thereof can be used, but copper is generally used.

In the present invention, the circuit board has an insulating layer 51 and a connection pad 54 formed on the surface of the insulating layer 51. A conductor wiring 52 is formed on the surface of the insulating layer 51, and the connection pad 54 is a part of the conductor wiring 52. In the present invention, the wiring board has a solder resist pattern made of a solder resist layer 53 on the surface of the circuit board, and a part of the connection pad 54 is exposed from the solder resist layer 53. In the case of a wiring board on which electronic components are mounted, the connection pad 54 on one surface is for connecting electronic components, and the connection pad 54 on another surface is for external connection. The connection pad 54 for connecting the electronic component is joined to the electronic component, and the connection pad 54 for external connection is joined to the conductor wiring of the external electric board.

The conductor wiring 52 and the connection pad 54 are formed by, for example, a subtractive method, a semi-additive method, an additive method, or the like. In the subtractive method, for example, an etching resist pattern is formed on a copper layer provided on the insulating layer 51, and exposure, development, etching, and resist peeling are performed to form a conductor wiring 52 and a connection pad 54. In the semi-additive method, a base metal layer for electrolytic copper plating is provided on the surface of the insulating layer 51 by electroless copper plating. Next, a plating resist pattern is formed on the base metal layer, and an electrolytic copper plating layer is formed on the surface of the exposed base metal layer. After that, the resist is peeled off and the underlying metal layer is flash-etched to form the conductor wiring 52 and the connection pad 54.

<Thin film thinning device>
5 to 7 are schematic views showing an example of the solder resist layer thinning apparatus of the present invention. In the present specification, the "thinning device for the solder resist layer" may be abbreviated as "thinning device". 5 to 7 are schematic views of the thin film device as viewed from above. The thinning apparatus of FIGS. 5 to 7 includes a thinning treatment unit 11 for micellarizing the components in the solder resist layer with the thinning treatment liquid 1, a micelle removal treatment unit 12 for removing micelles with the micelle removal liquid 10, and a water washing treatment. It is provided with a water washing treatment unit 31 for washing the surface of the solder resist layer with the liquid 32.

First, with reference to FIG. 4, a common structural portion between the thin film apparatus in the prior art and the thin film apparatus of the present invention will be described. In the thin film processing unit 11, the substrate 3 on which the solder resist layer charged from the charging port 7 is formed is transported in a state of being immersed in the thin film processing liquid 1 in the dip tank 2 by 4 pairs of transport rolls. .. By these treatments, the components in the solder resist layer on the substrate 3 are made into micelles by the thinning treatment liquid 1, and the micelles are insolubilized in the thinning treatment liquid 1.

The thinning treatment liquid 1 is sucked from the thinning treatment liquid suction port 14 in the thinning treatment liquid storage tank 13 by a thinning treatment liquid supply pump (not shown), and dips through the thinning treatment liquid supply pipe 15. It is supplied to the tank 2. The thinning treatment liquid 1 supplied to the dip tank 2 overflows and is recovered in the thinning treatment liquid storage tank 13 through the thinning treatment liquid recovery pipe 16. In this way, the thinning treatment liquid 1 circulates between the dip tank 2 and the thinning treatment storage tank 13. The excess thinning treatment liquid 1 is discharged from the thinning treatment liquid drain tube 17.

In the present invention, the thinning treatment liquid is preferably an aqueous solution containing an alkaline compound. The content of the alkaline compound is preferably 5 to 25% by mass, more preferably 5 to 20% by mass, and further preferably 6 to 17% by mass. When the content of the alkaline compound is less than 5% by mass, the thinning amount may be non-uniform. Further, when the content exceeds 25% by mass, precipitation of the alkaline compound is likely to occur, so that the stability of the thinning treatment liquid over time may become a problem. The pH of the thinning treatment liquid is preferably 10 or more. Further, a surfactant, a defoaming agent, a solvent and the like can be appropriately added to the thinning treatment liquid.

Examples of the alkaline compound include an inorganic alkaline compound. Examples of the inorganic alkaline compound include alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, alkali metal silicates and the like. Examples of the alkali metal include lithium, sodium, potassium and the like. In addition to the above-mentioned inorganic alkaline compounds, examples thereof include inorganic alkaline compounds such as ammonium phosphate and ammonium carbonate. Examples of the organic alkaline compound include monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, and trimethyl-2. -It can also contain an organic alkaline compound such as hydroxyethylammonium hydroxyside (choline).

The alkaline compound may be used alone or in combination of two or more. Further, the inorganic alkaline compound and the organic alkaline compound can be used in combination.

Further, a sulfate or a sulfite can be added to the thinning treatment liquid. Examples of the sulfate or sulfate include sulfates of alkali metals such as lithium, sodium and potassium or sulfates, sulfates of Group 2 elements such as magnesium and calcium, or sulfates.

The temperature of the thinning treatment liquid is preferably 10 to 50 ° C, more preferably 15 to 35 ° C. If the temperature is too low, the permeation rate of the alkaline compound into the solder resist layer may be slow, and it takes a long time to thin the desired thickness. On the other hand, if the temperature is too high, dissolution and diffusion proceed at the same time as the penetration of the alkaline compound into the solder resist layer, which may cause in-plane film thickness unevenness.

The substrate 3 discharged from the thin film processing unit 11 is charged into the micelle removal processing unit 12. In the micelle removal processing unit 12, the substrate 3 in which the components of the solder resist layer are insolubilized in the thin film processing liquid 1 in the thin film processing unit 11 is transported by 6 pairs of transport rolls. The micellar removing liquid 10 is supplied from the micellar removing liquid supply spray nozzle 21 to the conveyed substrate 3, and the micellar components of the solder resist layer are dissolved and removed at once.

The micelle removal liquid 10 sucks the micelle removal liquid 10 from the micelle removal liquid suction port 19 in the micelle removal liquid storage tank 18 with a micelle removal liquid supply pump (not shown), and removes the micelles via the micelle removal liquid supply pipe 20. The liquid is sprayed from the liquid supply spray nozzle 21 as the micelle removing liquid spray 22. The micelle removing liquid 10 flowing down from the substrate 3 is collected in the micelle removing liquid storage tank 18. In this way, the micelle removing liquid 10 circulates in the micelle removing processing unit 12. The excess micelle removing liquid 10 is discharged from the micelle removing liquid drain pipe 23.

As the micelle removing liquid, tap water, industrial water, pure water or the like can be used. Further, it is preferable to use an aqueous solution having a pH of 5 to 10 containing at least one alkaline compound as the micelle removing liquid, and the components of the solder resist layer insolubilized by the thinning treatment liquid are easily redispersed. Examples of the alkaline compound include the alkaline compounds exemplified in the above-mentioned thinning treatment liquid. When the pH of the micelle removing liquid is less than 5, the solder resist layer components may aggregate to form insoluble sludge and adhere to the thinned solder resist layer surface. On the other hand, when the pH of the micelle removing liquid exceeds 10, the solder resist layer may be excessively dissolved and diffused, and the amount of thinning in the plane may be uneven. Further, the pH of the micelle removing liquid can be adjusted by using sulfuric acid, phosphoric acid, hydrochloric acid or the like.

The conditions (temperature, time, spray pressure, supply flow rate) of the micelle removing liquid spray 22 are appropriately adjusted according to the dissolution rate of the components of the solder resist layer. Specifically, the temperature of the micelle removing liquid 10 in the micelle removing liquid storage tank 18 is preferably 10 to 50 ° C, more preferably 15 to 35 ° C. The spray pressure is preferably 0.01 to 0.5 MPa, more preferably 0.1 to 0.3 MPa. The supply flow rate of the micelle removing liquid 10 is preferably 0.030 to 1.0 L / min, more preferably 0.050 to 1.0 L / min, and 0.10 to 1.0 L / min per ^{1 cm 2 of the solder resist layer.} More preferred. When the supply flow rate is in this range, micelles of the components of the solder resist layer can be easily removed without leaving insoluble components on the surface of the solder resist layer after thinning. ^{If the supply flow rate per 1 cm 2 of the} solder resist layer is less than 0.030 L / min, poor dissolution of the components of the insolubilized solder resist layer may occur. On the other hand, if the supply flow rate exceeds 1.0 L / min, parts such as a pump required for supply become huge, and a large-scale device may be required. Further, if the supply amount exceeds 1.0 L / min, the effect on the dissolution and diffusion of the components of the solder resist layer may not change.

The substrate 3 discharged from the micelle removal processing unit 12 is charged into the water washing treatment unit 31. In the water washing treatment unit 31, in the micelle removal treatment unit 12, the substrate 3 from which the micelles of the solder resist layer are dissolved and removed is conveyed by 33 pairs of transport rolls. The washing treatment liquid 32 is supplied to the conveyed substrate 3 by the washing treatment liquid spray 37, and the substrate 3 is washed with water.

In the water washing treatment unit 31, after the micelle removal treatment, the thinning treatment liquid and the micelle removal liquid remaining and adhering to the surface of the solder resist layer are further washed away by the water washing treatment. As a method of washing with water, a spray method is preferable from the viewpoint of diffusion rate and uniformity of liquid supply. As the washing liquid, tap water, industrial water, pure water or the like can be used. Of these, it is preferable to use pure water. As the pure water, those generally used for industrial purposes can be used.

In the drying treatment, either hot air drying or room temperature air drying can be used, but preferably, a large amount of air is blown from an air gun or a blower to remove the water remaining on the surface of the solder resist layer with an air knife. A drying method that blows it off is good.

The features of the thinning apparatus of the present invention will be described in detail with reference to the drawings. The solder resist layer thinning apparatus of FIG. 5 has 6 pairs of transport rolls for transporting the substrate 3 having the solder resist layer formed on the surface thereof, and in the micelle removal processing unit 12, the spray nozzle 21 for supplying the micelle removal liquid is provided. , It is a fixed type, and it is arranged so that the injection directions are the same. The arrow 40 in the figure indicates the flow direction of the micelle removing liquid 10. In order to make the spray pattern 25 of the micelle removing liquid 10 easy to understand, the upper micelle removing liquid supply pipe 20 and the spray nozzle 21 for supplying the micelle removing liquid, which should be originally installed, are not shown.

FIG. 9 is a schematic view showing an arrangement example of a spray nozzle 21 for supplying a micellar removing liquid in the thinning apparatus of the present invention. FIG. 9-1 is a state diagram when the flow of the micellar removing liquid supply spray nozzle 21 and the micellar removing liquid spray 22 inside the micelle removal processing unit 12 is viewed from above of the thinning device. FIG. 9-2 illustrates the arrangement state of the micellar removing liquid supply spray nozzle 21 and the state of the micellar removing liquid spray 22 when viewed from the discharge side in the substrate transport direction of the thin film apparatus. The arrow 44 in FIG. 9-1 indicates the transport direction of the substrate, and the arrow 43 indicates the injection direction of the spray nozzle for supplying the micellar removing liquid. In order to realize a state in which all the micellar removing liquids flowing on the substrate 3 are flowing in the same direction, all the micellar removing liquid supply spray nozzles 21 may be tilted in the same direction. In this state, when the substrate 3 being conveyed is viewed from above, the injection directions 43 of all the micellar removing liquid supply spray nozzles face the same direction (FIG. 9-1). In this way, the same by performing the micelle removal treatment in a state where the spray nozzles 21 for supplying the micelle removing liquid are tilted in the same direction so that the spraying directions 43 of all the spray nozzles for supplying the micelle removing liquid are in the same direction. The flow of the micellar removing liquid in the direction can be sprayed on the surface of the solder resist layer of the substrate 3 (FIG. 9-2). Further, the injection direction 43 of the spray nozzle for supplying the micellar removing liquid is such that the micellar removing liquid is applied to the equipment upstream (thinning treatment unit 11) and the equipment downstream (water washing treatment unit 31) of the micellar removal treatment unit 12 that performs the micellar removal treatment. It is preferable to incline the substrate uniformly to the right or to the left, which is orthogonal to the transport direction 44 of the substrate, in order to prevent the film from flowing into the substrate. As a result, the micellar removing liquid flows in the same direction from the upstream side to the downstream side (flow direction 40 of the micellar removing liquid) of the spray nozzle for supplying the micellar removing liquid, so that the liquid flow is slow and uneven. It is possible to solve the problem that the amount of thinning of the solder resist layer becomes non-uniform in the three surfaces of the substrate, which is caused by the above.

Here, in the micelle removal processing unit 12, in order to more efficiently create a liquid flow in the same direction from the upstream side to the downstream side of the injection direction 43 of the spray nozzle for supplying the micelle removal liquid, the substrate 3 is conveyed. A straight type roll is used as the transport roll 6. The straight type roll has no unevenness on the surface and can adhere to the surface of the solder resist layer. When the surface of the solder resist layer and the straight type roll are in close contact with each other, the micelle removing liquid spray 22 is located on the downstream side along the transport roll 6 without being randomly turbulent between the transport rolls 6 in the front and rear rows. It is possible to create a linear liquid flow with a high flow rate. Examples of the straight type roll include a rubber roll, a sponge roll, a metal roll, a resin roll and the like. Among them, it has excellent rubber elasticity (sealing property, recoverability), low specific gravity, light weight, low hardness to medium hardness, less impact due to contact with solder resist layer, and high concentration alkaline aqueous solution. A roll of an olefin-based thermoplastic elastomer having excellent chemical resistance to the thinning treatment liquid is preferable. Examples of the olefin-based thermoplastic elastomer include THERMORUN (registered trademark).

The spray pattern of the spray nozzle includes a full cone, a fan shape, a linear shape, a layered shape, and the like. In the present invention, since it is important that the liquid flows in the same direction, the spray nozzle 21 for supplying the micellar removing liquid is not a swing type or a swing type, but a fixed type. Then, the fixed spray nozzle is tilted in the same direction to inject. When a fixed spray nozzle is used, it is preferable that the tilt angle of the spray nozzle is fixed so that the spray pattern is always uniform. The method of directly attaching and fixing the micellar removing liquid supply spray nozzle 21 to the micellar removing liquid supply pipe 20 at a desired tilt angle is preferable because it is not necessary to adjust the tilt angle when replacing the micellar removing liquid supply spray nozzle 21. In addition, after attaching an adapter (for example, manufactured by Ikeuchi Co., Ltd., trade name: UT ball joint) capable of adjusting the tilt angle to the micelle removal liquid supply pipe 20 and adjusting the tilt angle of the spray nozzle 21 for supplying the micelle removal liquid. , It may be a fixed method.

In the thinning of the solder resist layer, which has an extremely slow dissolution and removal rate of micelles, if the spray pattern is a full cone, the micelles cannot be completely removed and remain. This is because the alkaline compound necessary for dissolving and removing the insolubilized micelles is eluted, and the insolubilized micelles return to the original state of the components of the solder resist layer. In the present invention, when the spray pattern of the spray nozzle 21 for supplying the micellar removing liquid is fan-shaped, the area of the spray pattern (injection range) is narrower than when the spray pattern is a full cone, so that the supply flow rate per unit area is small. Can be increased, and the spray pressure per unit area can be increased. That is, since a strong impact can be given in a short time, it is possible to suppress the elution of the alkaline compound from the insolubilized solder resist layer and at the same time to dissolve and remove the insolubilized micelles at once. The fan-shaped spray pattern has an even distribution over the entire width direction, and a chevron-shaped spray pattern with a strong central part and a weakening toward the end, both of which can be used.

The difference in area between the filled cone and the fan-shaped spray pattern will be described. FIG. 11 is a schematic view showing a spray pattern of the micellar removing liquid, in which the spray nozzle 21 for supplying the micellar removing liquid and the spraying state of the micellar removing liquid are viewed from the discharge side in the substrate transport direction of the thin film apparatus. It is a state diagram when the injection range (spray pattern) of the micelle is seen from the upper direction of the thin film apparatus. The area of the spray pattern (fan shape) 25 is smaller than that of the spray pattern (filled cone) 24. This area varies depending on the supply flow rate, spray pressure, distance from the surface of the solder resist layer, and the inclination angle 47 of the spray nozzle 21 for supplying the micellar removing liquid, but the area ratio of the fan shape to the filled cone (fan shape / filled cone) is approximately. It is 15 to 20%.

Solder resists having an extremely slow dissolution and removal rate of micelles include, for example, solder resists containing an alkali-soluble resin having a small number of free carboxyl groups, solder resists containing an alkali-soluble resin having a large mass average molecular weight, and photopolymerization having a small amount of alkali-soluble resin. Examples thereof include solder resists containing a large amount of sex compounds.

In the solder resist layer thinning apparatus of FIG. 6, in the micelle removal processing unit 12, the arrangement of the micelle removal liquid supply spray nozzle 21 of the micelle removal liquid supply pipe 20 with respect to the transport direction of the substrate 3 is the micelle removal liquid. The front and rear rows of the supply pipe 20 are in a staggered position. This makes it possible to equalize the spray positions of the spray pattern 25 in the direction perpendicular to the transport direction of the substrate 3. Similarly, in the water washing treatment unit 31, the arrangement of the water washing treatment liquid supply spray nozzles 36 of the water washing treatment liquid supply pipe 35 is arranged in the front and rear rows of the water washing treatment liquid supply pipe 35 with respect to the transport direction of the substrate 3. The staggered positions make it possible to equalize the spray positions of the spray pattern 38 in the direction perpendicular to the transport direction of the substrate 3.

In the solder resist layer thinning apparatus of FIG. 7, 41 pairs of ring-type transfer rolls are installed in the micelle removal processing unit 12. When 41 pairs of ring-type transport rolls are used, the spray pattern 25 of the micelle removing liquid 10 diffuses more in the transport direction of the substrate 3 between the 41 pairs of transport rolls in the front and rear rows. Therefore, as compared with the four pairs of straight type transport rolls shown in FIGS. 5 and 6, it is difficult to create a linear liquid flow having a large flow rate. This drawback is that the ring-type transport roll 41 has a spoke or mesh cross section, or has a through hole, as long as the strength and durability of the ring roller are not impaired. It can be solved by passing a certain amount of liquid flow from the upstream side to the downstream side of the injection direction 43 by using the current one. When the ring type transport roll 41 is used, the ring rollers are arranged at regular intervals in the direction perpendicular to the transport direction of the substrate 3, and the ring rollers are arranged in a staggered position on the transport rolls 41 in the front and rear rows. The distance between the transport rolls 41 with respect to the transport direction of the substrate 3 can be made smaller than the diameter of the ring roller. This has the advantage that the substrate 3 is prevented from falling during transportation, and the substrate 3 having a thinner plate thickness can be transported. Examples of the ring type roll include a rubber roll, a sponge roll, a metal roll, a resin roll and the like. Among them, polyethylene, polypropylene, polycarbonate, polystyrene, and hard, which have a small specific gravity, are lightweight, have little impact due to contact with the resist layer, and have excellent chemical resistance to a thinning treatment liquid which is a high-concentration alkaline aqueous solution. In addition to polyvinyl chloride, acrylic resin (PMMA), fluororesin (for example, Teflon (registered trademark)) and the like, rolls of olefin-based thermoplastic elastomers can be used. Examples of the olefin-based thermoplastic elastomer include THERMORUN (registered trademark).

In the solder resist layer thinning apparatus of FIG. 8, in the micelle removal processing unit 12, the spray pattern 25 of the micelle removal liquid sprayed from the micelle removal liquid supply spray nozzle 21 of the micelle removal liquid supply pipe 20 is fan-shaped. Further, the spray patterns 25 are aligned in a straight line in the direction perpendicular to the transport direction of the substrate 3. The fan-shaped spray pattern 25 can adjust the injection direction by rotating the mounting angle of the spray nozzle 21 for supplying the micellar removing liquid. As a result, a high-pressure spray can be more effectively sprayed onto the solder resist layer on the substrate 3, and even when the amount of thinning is large, the insolubilized solder resist layer can be completely removed. ..

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to this example.

(Example 1)
A dry film-like solder resist (manufactured by Taiyo Ink Mfg. Co., Ltd., trade name: PFR-800 AUS SR1) is applied to a copper-clad laminate (area 170 mm × 200 mm, copper foil thickness 18 μm, substrate thickness 0.4 mm) as described above. A solder resist layer having a film thickness of 30 μm was formed by vacuum thermocompression bonding (lamination temperature 75 ° C., suction time 30 seconds, pressurization time 10 seconds).

Next, after peeling off the carrier film, a solder resist layer thinning device (FIG.) including a thinning treatment unit 11 provided with a dip tank 2 and a micelle removing treatment unit 12 for removing micelles with a micelle removing liquid 10. 7) was used to thin the solder resist layer.

The micellar removing liquid supply spray nozzle 21 used is a fixed type, and the spray pattern 25 thereof is fan-shaped. Further, in FIG. 9-1 (state view of the micellar removing liquid supply spray nozzle 21 and the micellar removing liquid spray 22 inside the micelle removal processing unit 12 when viewed from above), the micellar removing liquid is supplied. The injection directions 43 of the spray nozzles all face the same direction, and FIG. 9-2 (arrangement state of the micellar removing liquid supply spray nozzle 21 and the micellar removing liquid when viewed from the discharge side in the substrate transport direction of the thin film device). In the state of the spray 22), the inclination angle 47 formed by the vertical line 45 with respect to the substrate and the center line 46 of the spray nozzle was 25 degrees. That is, in the micelle removal processing unit 12, all the spray nozzles 21 for supplying the micelle removal liquid were installed at an angle of 25 degrees to the left with respect to the transport direction 44 of the substrate.

Using 10% by mass of sodium metasilicate (temperature 25 ° C.) as the thinning treatment liquid 1, the thinning treatment was performed so that the immersion treatment time in the dip tank 2 of the thinning treatment unit 11 was 30 seconds, and the solder resist was performed. The components of the layer were made into micelles. After that, in the micelle removal treatment unit 12, an aqueous solution having a pH of 8 (temperature 25 ° C.) containing sodium metasilicate was used as the micelle removal liquid 10 and the supply flow rate was 1.2 L / from the spray nozzle 21 for supplying the micelle removal liquid. It was supplied to the substrate 3 in min, the insolubilized micelles were removed, and the solder resist layer was thinned. ^{The supply flow rate of the micelle removing liquid per 1 cm 2 of the} solder resist layer was 0.10 L / min, and the spray pressure was 0.2 MPa. Then, it was washed with water and dried.

After washing with water and drying, the thickness of the thinned portion of the solder resist layer was measured at 10 points. The maximum value was 16.0 μm, the minimum value was 14.0 μm, and the average thickness was 15.0 μm. .. Moreover, when the surface of the thinned solder resist layer was observed with an optical microscope, it was confirmed that the surface was a smooth thin film with no processing unevenness.

(Example 2)
The solder resist layer was thinned by the same method as in Example 1 except that the solder resist layer thinning apparatus of FIG. 8 was used. In the first embodiment, the spray patterns 25 are not aligned in a straight line in the direction perpendicular to the transport direction of the substrate 3 (FIG. 7), whereas in the second embodiment, the spray pattern 25 is the transport direction of the substrate 3. They are aligned in a straight line in the vertical direction with respect to (Fig. 8). Further, the inclination angle 47 formed by the vertical line 45 with respect to the substrate and the center line 46 of the spray nozzle was 25 degrees.

After washing with water and drying, the thickness of the thinned portion of the solder resist layer was measured at 10 points. The maximum value was 15.5 μm, the minimum value was 14.5 μm, and the average thickness was 15.0 μm. .. Moreover, when the surface of the thinned solder resist layer was observed with an optical microscope, it was confirmed that the surface was a smooth thin film with no processing unevenness.

(Example 3)
The solder resist layer was thinned by the same method as in Example 1 except that the dipping treatment time in the dip tank 2 of the thinning treatment unit 11 was 60 seconds.

After washing with water and drying, the thickness of the thinned portion of the solder resist layer was measured at 10 points. The maximum value was 9.0 μm, the minimum value was 7.0 μm, and the average thickness was 8.0 μm. .. Moreover, when the surface of the thinned solder resist layer was observed with an optical microscope, it was confirmed that the surface was a smooth thin film with no processing unevenness.

(Comparative Example 1)
The solder resist layer was thinned by the same method as in Example 1 except that the solder resist layer thinning apparatus of FIG. 10 was used. That is, the micellar removing liquid supply spray nozzle 21 used is a fixed type, and the spray pattern 24 thereof is a filled cone.

After washing with water and drying, the thickness of the thinned portion of the solder resist layer was measured at 10 points. The maximum value was 16.0 μm, the minimum value was 10.0 μm, and the average thickness was 13.0 μm. .. Further, when the surface of the thinned solder resist layer was observed with an optical microscope, the solder resist layer that could not be completely removed by the micelle removing liquid spray 22 remained.

The method for forming a solder resist pattern of the present invention can be applied to, for example, an application for forming a solder resist pattern of a circuit board provided with a connection pad for flip chip connection in a part of wiring.

1 Thin film treatment liquid 2 Dip tank 3 Substrate 4 Conveyance roll (straight type)
6 Transport roll (straight type)
7 Input port 10 micelle removal liquid 11 thinning treatment unit 12 micelle removal treatment unit 13 thinning treatment liquid storage tank 14 thinning treatment liquid suction port 15 thinning treatment liquid supply pipe 16 thinning treatment liquid recovery pipe 17 thinning treatment liquid Drain tube 18 Micelle removing liquid storage tank 19 Micelle removing liquid suction port 20 Micelle removing liquid supply pipe 21 Micelle removing liquid supply spray nozzle 22 Micelle removing liquid spray 23 Micelle removing liquid Drain pipe 24 Spray pattern (micellar removing liquid, filled cone)
25 Spray pattern (micellar remover, fan shape)
31 Washing treatment unit 32 Washing treatment liquid 33 Conveying roll (ring type)
34 Washing treatment liquid suction port 35 Washing treatment liquid supply pipe 36 Water washing treatment liquid supply spray nozzle 37 Washing treatment liquid spray 38 Spray pattern (water washing treatment liquid, fan shape)
40 Flow direction of micelle remover 41 Conveying roll (ring type)
43 Injection direction of spray nozzle for supplying micellar remover 44 Direction of transport of substrate 45 Vertical wire to substrate 46 Center line of spray nozzle 47 Tilt angle 51 Insulation layer 52 Conductor wiring 53 Solder resist layer 54 Connection pad

Claims (2)

In a solder resist layer thinning device including a thinning treatment unit for micellarizing components of a solder resist layer that has not been cured by the thinning treatment liquid and a micelle removal treatment unit for removing micelles with a micelle removing liquid.
The micelle removal processing unit has a spray nozzle for supplying a micelle removal liquid, and the micelle removal processing unit has a spray nozzle for supplying the micelle removal liquid.
The spray nozzle for supplying the micellar remover is a fixed type and is arranged so that the injection directions are the same.
A solder resist layer thinning device characterized in that the spray pattern of the spray nozzle for supplying the micellar remover is fan-shaped. The solder resist layer thinning apparatus according to claim 1, wherein the spray nozzle for supplying the micellar removing liquid is arranged so that the spray patterns are aligned in a straight line in the direction perpendicular to the transport direction.

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