TWM620419U - Thin film device for solder resist layer - Google Patents

Abstract

This invention provides a device for thinning the solder resist layer. In the device for thinning the solder resist layer, even when the solder resist layer with a very slow dissolution and removal rate of micelles is thinned, there will be no remaining unusable glue. The solder resist layer completely removed by the beam removal liquid has a smooth thinning surface. The device for thinning the solder resist layer of the present invention is characterized by including a thin film processing unit that micellizes the components of the solder resist layer that has not been cured using a thin film processing liquid, and a micelle removal device using a micelle removing liquid A device for thinning the solder resist layer of the micelle removal processing unit. The micelle removal processing unit has a spray nozzle for the supply of the micelle removal liquid, and the spray nozzle for the supply of the micelle removal liquid is a fixed type, and the spray direction is the same direction The spray pattern of the spray nozzle for supplying micelle removal liquid is fan-shaped.

Description

Thin film device for solder resist layer

This creation relates to a device for thinning the solder resist layer.

On wiring boards inside various electrical devices, in order not to adhere solder to the conductor wiring of the circuit board that does not require soldering, a solder resist pattern is formed so that the portions that do not require soldering are covered with a solder resist layer. In addition, the solder resist pattern plays a role of preventing the oxidation of the 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, the mounting of electronic components by flip-chip bonding is an effective method for achieving high speed and high density. In flip-chip bonding, a part of the conductor wiring becomes a bonding pad for flip-chip bonding, and for example, solder bumps arranged on the bonding pad are bonded to electrode terminals of a semiconductor wafer.

As a method of forming a solder resist pattern on a circuit board, a photolithography method is generally known. In the photolithography method, a solder resist layer 53 is formed on a circuit substrate, wherein the circuit substrate has a bonding pad 54 and a conductor wiring 52 on the insulating layer 51, and then exposure and development are performed to remove the solder resist layer 53 around the bonding pad 54 , The opening is provided, thereby forming the Solder"Mask"Defined (SMD) structure shown in FIG. 1 and the Non"Solder"Mask"Defined (NSMD) structure shown in FIG.

In the SMD structure, since the vicinity of the bonding pad 54 is covered by the solder resist layer 53, in order to reliably electrically connect the electrode terminals of the electronic component and the bonding pad 54, it is necessary to ensure that the bonding area formed on the exposed surface of the bonding pad 54 The necessary amount of solder has the problem of increasing the size of the bonding pad 54. In addition, in order to reliably cover the vicinity of the bonding pad 54 with the solder resist layer 53, considering the processing accuracy, it is necessary to ensure that the width of the portion of the bonding pad 54 covered with the solder resist layer 53 is large, so that the bonding pad 54 may be larger. The problem of chemistry. On the other hand, in the bonding pad 54 of the NSMD structure, since the entire bonding pad 54 is exposed from the solder resist layer 53, the bonding area with the solder is large, and the bonding pad 54 can be miniaturized compared with the case of the SMD structure. However, in the NSMD structure, since the bonding pad 54 is completely exposed from the solder resist layer 53, an electrical short circuit due to solder may occur between the bonding pads 54 adjacent to each other.

In order to solve this problem, the following method for forming a solder resist pattern has been disclosed, which at least sequentially includes the steps of forming a solder resist layer 53 on a circuit board having a bonding pad 54 and thinning the solder resist layer 53 that has not been cured. The process until the thickness of the solder resist layer 53 becomes equal to or less than the thickness of the bonding pad 54 (for example, refer to Patent Documents 1 to 4). In this forming method, as shown in FIG. 3, a structure in which the surface of the bonding pad 54 is exposed from the solder resist layer 53 and a part of the side surface of the bonding pad 54 is covered by the solder resist layer 53 can be obtained. In the structure shown in FIG. 3, electrical shorts caused by solder between the bonding pads 54 adjacent to each other are less likely to occur, and the amount of solder necessary to reliably electrically connect the electrode terminals of the electronic component and the bonding pads 54 can be secured. The bonding pad 54 can be miniaturized, and a high-density wiring wiring board with excellent electrical connection reliability can be manufactured.

In addition, Patent Document 5 discloses the following resist layer thinning device, which includes at least four processing units: a thin film processing unit that dips a substrate on which a resist layer is formed on a high surface. The micelles of the components of the resist layer are temporarily insolubilized in the alkali aqueous solution (thinning treatment solution) of high concentration, making it difficult to dissolve and diffuse into the treatment solution; the micelle removal processing unit uses the micelle removal solution to spray at one fell swoop The micelles are dissolved and removed; a water washing treatment unit, which washes the surface with a water washing treatment liquid; and a drying treatment unit, which removes the water washing treatment liquid.

A part of the apparatus for thinning the resist layer will be described using the schematic cross-sectional view shown in FIG. 4. In the thin film processing unit 11, the substrate 3 on which the resist layer is formed is input from the input port 7. The substrate 3 is conveyed by the pair of conveying rollers 4 while being immersed in the thinning treatment liquid 1 in the dipping tank 2 to perform the thinning of the resist layer. After that, the substrate 3 is transported to the micelle removal processing unit 12. In the micelle removal processing unit 12, to the substrate 3 transported by the pair of transport rollers 4, the micelle removal liquid spray 22 is supplied from the micelle removal liquid supply spray nozzle 21 through the micelle removal liquid supply pipe 20. The resist layer on the substrate 3 is in the immersion tank 2 inside the thin film processing unit 11, and the micelles of the resist layer components are temporarily insoluble in the thin film by the thin film processing liquid 1 which is a high-concentration alkaline aqueous solution. Treatment solution 1. After that, the micelles are removed by the micelle removing liquid spray 22, thereby thinning the resist layer. Patent Document 5 has a description that "it is important that the micelle removal is performed at one stroke by the micelle removal liquid spray 22, and it is preferable to perform it quickly under the conditions of a certain water pressure and flow rate".

In various conventional liquid processing apparatuses, as the liquid supply method using spray, the liquid is usually sprayed vertically from a fixed or oscillating spray nozzle to the surface of the substrate, and the oscillating spray nozzle is used to make the liquid reach The method of spraying liquid onto the surface of the substrate while the angle is constantly changing, etc. In these conventional liquid supply methods, the liquid flow on the substrate is slow and tends to become uneven. Therefore, when the micelle removal process is performed by these liquid supply methods, the micelle removal becomes uneven, and the amount of the resist layer thinning treatment may become uneven.

In addition, Patent Document 6 discloses a thin film forming method in which the spray nozzle is inclined in the width direction at right angles to the substrate conveying direction, and the inclination angle is in the range of 30 to 70 degrees, thereby improving the The flow of micelle removal solution. However, in Patent Document 6, although the inclination angle of the spray nozzle is described, there is no description about the orientation of the spray nozzle. Therefore, only by adjusting the angle, the right and left flows of the micellar removal solution orthogonal to the substrate conveying direction may occur. The flow of the micelle removal solution on the substrate is still slow and uneven, and there is corrosion resistance. When the amount of the agent layer becomes non-uniform.

In order to solve this problem, Patent Document 7 discloses a resist layer thinning device that can solve the problem of thinning the resist layer on the substrate surface by tilting the spray nozzle in a single direction. The problem of uneven volume. In Patent Document 7, in order to create a single-direction liquid flow, it is proposed to spray a fixed spray nozzle obliquely, but in order to spray the spray uniformly without omission, it is preferable to use an evenly distributed solid cone type capable of spraying over a wide range (Japanese original : The description of the nozzle of the filling cone type. However, in the case of thinning the solder resist layer, which has a very slow rate of dissolution and removal of micelles, there is a residual solder resist layer that cannot be completely removed with the micelle removal liquid, and the thinned solder resist layer has different thicknesses. Partially, the thinning surface becomes uneven.

As described above, the residual solder resist layer that cannot be completely removed, the part with different thickness in the thinned solder resist layer, and the unevenness of the filmed surface may be the cause of the deterioration of weather resistance, which may lead to the finished product. The problem of lower rate.

Prior art literature Patent literature Patent Document 1: Japanese Patent Application Publication No. 2011-192692 Patent Document 2: International Publication No. 2012/043201 Pamphlet Patent Document 3: Japanese Patent Application Publication No. 2017-107144 Patent Document 4: Japanese Patent Application Publication No. 2017-103444 Patent Document 5: Japanese Patent Laid-Open No. 2012-27299 Patent Document 6: JP 2012-59755 A Patent Document 7: Utility Model Registration No. 3207408 Bulletin

New problems to be solved The purpose of the present invention is to provide a device for thinning a solder resist layer. In the device for thinning a solder resist layer, even when the solder resist layer with a very slow dissolution and removal rate of micelles is thinned, it is not The solder resist layer that cannot be completely removed with the micellar removal liquid remains, and the filmed surface becomes smooth.

Technical means used to solve the problem The creators of the present invention found that these problems can be solved by using the following solutions.

(1) A device for thinning a solder resist layer, which includes a thin film processing unit that micellizes the components of the solder resist layer that is not cured with a thin film processing liquid, and a micelle that uses a micelle removing liquid to remove micelles The thin filming device for removing the solder resist layer of the processing unit is characterized in that: The micelle removal processing unit has a spray nozzle for supplying micelle removal liquid, The spray nozzle for the supply of the micelle removal liquid is a fixed type and is arranged so that the spray direction is the same direction, The spray pattern of the spray nozzle for supplying micelle removal liquid is fan-shaped.

(2) The device for thinning a solder resist layer according to (1) above, characterized in that the spray pattern is arranged in a straight line in a direction perpendicular to the conveying direction, and the micelle removing liquid supply is arranged Spray nozzle.

effect According to the present invention, it is possible to provide a device for thinning a solder resist layer. In the device for thinning a solder resist layer, even when the solder resist layer with a very slow dissolution and removal rate of micelles is thinned, it is not The solder resist layer that cannot be completely removed with the micellar removal liquid remains, and the filmed surface becomes smooth.

＜Thinning process＞ The thinning process of the solder resist layer using the thinning treatment liquid of the present invention is a process including thinning treatment and micelle removal treatment. The thinning treatment is to use the thinning treatment liquid to make the components of the solder resist layer micelles The micelle removal treatment is to dissolve and remove the micelles in one fell swoop by spraying the micelle removal solution. In addition, water washing treatment and drying treatment may also be included. The water washing treatment uses a water washing treatment liquid to rinse the surface of the solder resist layer that has not been completely removed, the remaining adhered thin film treatment liquid and the micelle removal liquid, and the drying treatment removes the water washing treatment liquid.

＜Thin film treatment＞ The thinning treatment using the thinning treatment liquid may also use methods such as paddle treatment, spray treatment, brushing, scraping, etc. However, it is preferably performed by immersion treatment. In the immersion treatment, the substrate on which the solder resist layer is formed is dipped in a thin film treatment liquid. Treatment methods other than immersion treatment tend to generate bubbles in the alkaline aqueous solution, and the generated bubbles adhere to the surface of the solder resist layer during the thinning treatment, and the film thickness may become uneven. In the case of spray treatment, in order not to generate bubbles, the spray pressure must be reduced as much as possible.

In this creation, the thickness of the solder resist layer after thinning is determined based on the thickness of the solder resist layer after formation and the amount of the solder resist layer being thinned. In addition, in this creation, 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 development type solder resist can be used. In addition, it may be a liquid resist or a dry film resist. In the case of a liquid resist, it may be a single-component type or a two-component type. As long as it is a solder resist that can be thinned with a high-concentration alkali aqueous solution (thinning treatment solution) and can be developed with a developer that is a lower concentration of the alkali aqueous solution than the thinning treatment solution, no matter what kind of solder resist Both can be used. The alkali-developing type solder resist contains a photocrosslinkable resin component. The photocrosslinkable resin component contains, for example, at least one selected from alkali-soluble resins and photopolymerizable compounds, and further contains a photopolymerization initiator, and may contain thermosetting agents, fillers, and the like.

Examples of alkali-soluble resins include acrylic resins, methacrylic resins, styrene resins, epoxy resins, amide resins, amide epoxy resins, alkyd resins, and phenolic resins. The organic polymer of is preferably a resin obtained by polymerizing (radical polymerization, etc.) a monomer (polymerizable monomer) having an ethylenically unsaturated double bond. These alkali-soluble resins are formed from polymers containing carboxyl groups in the molecule and polymers containing carboxyl groups that also have ethylenically unsaturated double bonds in the molecule. Since they have many free carboxyl groups in the side chains of the main chain, they can be used for thinning. Development of alkaline aqueous solution. In addition, the solder resist layer after being crosslinked 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 kinds.

Examples of monomers having ethylenically unsaturated double bonds include styrene, vinyl toluene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, and Styrene derivatives such as ethoxystyrene, p-chlorostyrene, and p-bromostyrene; acrylamides such as diacetone acrylamide; acrylonitrile; vinyl ethers such as vinyl-n-butyl ether; (methyl ) Alkyl acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, ( 2, 2, 2-trifluoroethyl methacrylate, 2, 2, 3, 3-tetrafluoropropyl (meth)acrylate, (meth)acrylic acid, α-bromo(meth)acrylic acid, (Meth)acrylic monomers such as α-chloro(meth)acrylic acid, β-furyl(meth)acrylic acid, β-styryl(meth)acrylic acid; maleic acid, maleic anhydride, maleic acid Maleic acid monomers such as monomethyl ester, monoethyl maleate, and monoisopropyl maleate; fumaric acid, cinnamic acid, α-cyanocinnamic acid, itaconic acid, crotonic acid, propionic acid Wait.

Examples of photopolymerizable compounds include compounds obtained by reacting α, β-unsaturated carboxylic acids with polyhydric alcohols; bisphenol A-based (meth)acrylate compounds; and α, β-unsaturated carboxylic acids and A compound obtained by reacting a compound containing a glycidyl group; a urethane monomer such as a (meth)acrylate compound having a urethane bond in the molecule; a nonylphenoxy polyvinyl acrylate acrylate; γ -Chloro-β-hydroxypropyl-β'-(meth)acryloyloxyethyl-phthalate, β-hydroxyalkyl-β'-(meth)acryloyloxyalkyl- Phthalic acid compounds such as phthalates; alkyl (meth)acrylate, ethylene glycol, propylene glycol modified nonylphenyl (meth)acrylate, etc. Here, ethylene glycol and propylene glycol mean ethylene oxide and propylene oxide, the compound modified with ethylene glycol is a compound having a block structure of ethylene oxide group, and the compound modified with propylene glycol has an epoxy A compound with a block structure of propylene group. These photopolymerizable compounds may be used alone or in combination of two or more kinds.

Examples of photopolymerization initiators 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-di Methylamino-1-(4-morpholinophenyl)-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-acetone, etc. Aromatic ketones; 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1, 2-benzoanthraquinone, 2, 3-benzoanthraquinone, 2-phenyl Anthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthrenequinone, 2-methyl-1,4-naphthalene Quinone, 2,3-dimethylanthraquinone and other quinones; benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether and other benzoin ether compounds; benzoin, methylbenzoin, acetone Benzoin compounds such as benzoin; dimethyl ketal and other derivatives of biphenyl; 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl) Chlorophenyl)-4,5-bis(methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxy Phenyl)-4,5-diphenylimidazole dimer, 2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer, etc. 2, 4, 5-triarylimidazole dimer Compounds; 9-phenylacridine, 1, 7-bis(9, 9'-acridinyl) heptane and other acridine derivatives; 2, 4, 6-trimethylbenzyl diphenyl phosphine oxide , Bis (2, 4, 6-trimethylbenzyl) phenyl phosphine oxide and other phosphine oxide compounds; 1, 2-octanedione-1-[4-(phenylthio)-2-( O-benzyl oxime)], 1-[9-ethyl-6-(2-methylbenzyl)-9H-oxazol-3-yl]ethanone-1-(O-acetyl oxime) Oxime) and other oxime esters; oxyphenylacetic acid 2-[2-oxo-2-phenylacetoxyethoxy] ethyl ester, oxyphenylacetic acid 2-(2-hydroxyethoxy) Oxyphenyl acetate such as ethyl ester; bis(η ⁵ -2, 4-cyclopentadien-1-yl)-bis(2, 6-difluoro-3-(1H-pyrrol-1-yl) Phenyl) titanium and other titanocene compounds; N-phenylglycine, N-phenylglycine derivatives, coumarin-based compounds, etc. The substituents of the aryl groups of the two 2,4,5-triarylimidazoles in the above 2,4,5-triarylimidazole dimer may be the same to form a symmetric compound, or they may be different to form an asymmetric compound. In addition, it is also possible to combine a thioxanthone-based compound and a tertiary amine compound like a combination of diethylthioxanthone and dimethylaminobenzoic acid. These may be used alone, or two or more of them may be used in combination.

In order to improve the physical strength of the solder resist layer, etc., if necessary, a thermosetting component may be contained as a curing agent. As such thermosetting components, amino resins such as melamine resins and benzoguanamine resins, blocked isocyanate compounds, cyclic carbonate compounds, polyfunctional epoxy compounds, polyfunctional oxetane compounds, episulfide resins, etc. can be used. It reacts (crosslinks) with the carboxyl group of the alkali-soluble resin, and the properties such as heat resistance and chemical resistance are improved.

Either inorganic or organic fillers can be used as fillers. 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 diameter of the filler is preferably in the range of 0.1 to 20 μm. The above-mentioned average particle diameter is more preferably 0.2 μm or more, more preferably 4 μm or less, and still more preferably 2 μm or less.

The method of forming the solder resist layer on the surface of the substrate may be any method. For example, in the case of liquid resists, screen printing methods, roll coating methods, spray methods, dipping methods, curtain coating methods, bar coating methods, air knife methods, hot melt methods, gravure coating methods, Brush coating method, offset printing method, etc. In the case of a dry film resist, a lamination method, a vacuum lamination method, etc. can be mentioned.

Examples of the substrate include flexible substrates and rigid substrates. The flexible substrate is a laminated substrate in which the insulating layer uses polyimide, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polymer, etc., and a metal layer is provided on one or both sides of the insulating layer , Great flexibility. Rigid substrates include, for the insulating layer, an insulating substrate obtained by impregnating a glass cloth with a thermosetting resin such as bismaleimide triazine resin and epoxy resin is superimposed as an insulating layer, and the insulating layer is placed on one side of the insulating substrate. Or a laminated substrate with metal layers on both sides. In addition, a multilayer board produced by laminating an insulating material for Build-Up called a prepreg after the inner layer wiring pattern is processed can also be cited. As the material of the metal layer, any metal such as copper, aluminum, silver, nickel, chromium, gold, or their alloys can be used, but copper is generally used.

In this creation, the circuit substrate has an insulating layer 51 and a bonding pad 54 formed on the surface of the insulating layer 51. On the surface of the insulating layer 51, a conductor wiring 52 is formed, and the bonding pad 54 is a part of the conductor wiring 52. In this creation, regarding the wiring board, the surface of the circuit board has a solder resist pattern formed by the solder resist layer 53, and a part of the bonding pad 54 is exposed from the solder resist layer 53. In the case of a wiring board on which an electronic component is mounted, the bonding pad 54 on one surface is used for electronic component connection, and the bonding pad 54 on the other surface is used for external connection. The bonding pad 54 for connecting the electronic component is bonded to the electronic component, and the bonding pad 54 for external connection is bonded to the conductor wiring of the external electric board.

The conductor wiring 52 and the bonding pad 54 can be formed by, for example, a subtractive method, a semi-additive method, an additive method, or the like. In the subtractive method, for example, a resist pattern is formed on a copper layer provided on the insulating layer 51, and exposure, development, etching, and resist stripping are performed to form the conductor wiring 52 and the bonding 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. Then, 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, resist stripping and flash etching of the underlying metal layer are performed to form conductor wiring 52 and bonding pad 54.

＜Thin film equipment＞ 5 to 7 are schematic diagrams showing an example of the device for thinning the solder resist layer of the present invention. In this specification, the "means for forming a thin film of a solder resist layer" may be abbreviated as a "means for forming a thin film". 5 to 7 are schematic diagrams of the thin film forming apparatus viewed from above. The thin film forming apparatus of FIGS. 5 to 7 includes: a thin film processing unit 11 that micelles the components in the solder resist layer using a thin film processing liquid 1, a micelle removal processing unit 12 that removes micelles using a micelle removing liquid 10, And the water washing treatment unit 31 that washes the surface of the solder resist layer with the water washing treatment liquid 32.

First, using FIG. 4, the common structural parts of the thin film forming apparatus of the prior art and the thin film forming apparatus of the present invention will be described. In the thin film processing unit 11, the substrate 3 on which the solder resist layer is formed, which is input from the input port 7, is conveyed by the pair of conveying rollers 4 while being immersed in the thin film processing liquid 1 in the immersion tank 2. Through these treatments, the components in the solder resist layer on the substrate 3 are micellized by the thinning treatment liquid 1 so that the micelles are insoluble in the thinning treatment liquid 1.

The thin film treatment liquid 1 is sucked from the thin film treatment liquid suction port 14 in the thin film treatment liquid storage tank 13 by a thin film treatment liquid supply pump (not shown), and to the immersion tank 2 through the thin film treatment liquid supply pipe 15 supply. The thin film treatment liquid 1 supplied to the dipping tank 2 overflows, passes through the thin film treatment liquid recovery pipe 16 and is recovered to the thin film treatment liquid storage tank 13. As described above, the thin film treatment liquid 1 circulates between the dipping tank 2 and the thin film treatment liquid storage tank 13. The remaining part of the thin film treatment liquid 1 is discharged from the thin film treatment liquid discharge pipe 17.

In the present invention, the thin film treatment liquid is preferably an aqueous solution containing a basic compound. The content of the basic compound is preferably 5 to 25% by mass, more preferably 5 to 20% by mass, and still more preferably 6 to 17% by mass. When the content of the basic compound is less than 5% by mass, the amount of film formation may become uneven. In addition, when the content is more than 25% by mass, the precipitation of the basic compound is likely to occur, and therefore the stability of the thin film treatment solution over time may become a problem. The pH of the thin film treatment liquid is preferably 10 or more. In addition, surfactants, defoamers, solvents, etc. may be appropriately added to the thin film treatment liquid.

Examples of basic compounds include inorganic basic compounds. Examples of inorganic basic compounds include alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, and alkali metal silicates. Examples of alkali metals include lithium, sodium, potassium, and the like. In addition to the above-mentioned inorganic basic compounds, inorganic basic compounds such as ammonium phosphate and ammonium carbonate can also be cited. As an organic basic compound, it may also contain monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, cyclohexylamine, tetramethylammonium hydroxide ( TMAH), tetraethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide (choline) and other organic alkaline compounds.

The basic compound may be used alone or in combination of two or more kinds. In addition, an inorganic basic compound and an organic basic compound may be used in combination.

In addition, sulfate or sulfite may be added to the thin film treatment liquid. Examples of sulfates or sulfites include sulfates or sulfites of alkali metals such as lithium, sodium, and potassium, and sulfates or sulfites of group 2 elements such as magnesium and calcium.

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

The substrate 3 discharged from the thinning processing unit 11 is put into the micelle removal processing unit 12. In the micelle removal processing unit 12, the substrate 3 on which the components of the solder resist layer are insoluble in the thinning processing liquid 1 in the thinning processing unit 11 is transported by the pair of transport rollers 6. The micelle removal liquid 10 is supplied from the spray nozzle 21 for the micelle removal liquid supply to the conveyed substrate 3, and the micelles of the components of the solder resist layer are dissolved and removed at one stroke.

The micellar removal liquid suction port 19 in the micellar removal liquid storage tank 18 sucks the micelle removal liquid 10 by a pump (not shown) for supplying micelle removal liquid, and the micelle removal liquid is removed from the micelle removal liquid through the micelle removal liquid supply pipe 20 The spray nozzle 21 for supply sprays the micelle removal liquid 10 as the micelle removal liquid spray 22. The micelle removal liquid 10 flowing down from the substrate 3 is recovered to the micelle removal liquid storage tank 18. As described above, the micelle removal liquid 10 circulates in the micelle removal processing unit 12. The remaining part of the micellar-removed liquid 10 is discharged from the micellar-removed liquid discharge pipe 23.

As the micelle removal liquid, tap water, industrial water, pure water, etc. can be used. In addition, it is preferable to use an aqueous solution of pH 5 to 10 containing at least one basic compound as the micelle removal liquid, so that the components of the solder resist layer insoluble in the thin film treatment liquid can be easily redispersed. Examples of the basic compound include the basic compounds exemplified in the above-mentioned thin film treatment liquid. When the pH of the micelle removal liquid is less than 5, the components of the solder resist layer aggregate and become insoluble dross, which may adhere to the surface of the thinned solder resist layer. On the other hand, when the pH of the micelle removal liquid is greater than 10, the solder resist layer is excessively dissolved and diffused, and unevenness in the amount of film formation in the plane may easily occur. In addition, the micellar removal liquid can be adjusted to pH using sulfuric acid, phosphoric acid, hydrochloric acid, or the like.

The conditions (temperature, time, spray pressure, and supply flow rate) of the micelle removal liquid spray 22 can be appropriately adjusted according to the dissolution rate of the components of the solder resist layer. Specifically, the temperature of the micelle removal liquid 10 in the micelle removal liquid storage tank 18 is preferably 10 to 50°C, and more preferably 15 to 35°C. In addition, the spray pressure is preferably 0.01 to 0.5 MPa, and more preferably 0.1 to 0.3 MPa. The supply flow rate of the micelle removal liquid 10 is preferably ^{0.030 to 1.0 L/min per 1 cm 2 of the} solder resist layer, more preferably 0.050 to 1.0 L/min, and even more preferably 0.10 to 1.0 L/min. If the supply flow rate is within this range, insoluble components will not remain on the surface of the solder resist layer after thinning, and the micelles of the components of the solder resist layer will be easily removed. If the supply flow rate per 1 cm ^{2 of the} solder resist layer is less than 0.030 L/min, it may cause poor dissolution of the components of the insolubilized solder resist layer. On the other hand, if the supply flow rate exceeds 1.0 L/min, components such as pumps necessary for supply become huge, and a large-scale device may be required. In addition, when the supply amount is greater than 1.0 L/min, the effect provided by the dissolution and diffusion of the components of the solder resist layer does not change.

The substrate 3 discharged from the micelle removal processing unit 12 is put into the water washing processing unit 31. In the water washing treatment unit 31, the micelle substrate 3 from which the components of the solder resist layer have been dissolved and removed in the micelle removal treatment unit 12 is transported by the pair of transport rollers 33. The washing treatment liquid 32 is sucked in from the washing treatment liquid suction port 34 by a water washing treatment liquid supply pump (not shown), and the water washing treatment liquid 32 is supplied to the substrate 3 being transported by the water washing treatment liquid spray 37 through the water washing treatment liquid supply pipe 35 , 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 on the surface of the solder resist layer are further washed with a water washing treatment liquid. As a method of the water washing treatment, a spray method is preferred from the viewpoints of the diffusion rate and the uniformity of the liquid supply. As the water washing treatment liquid, tap water, industrial water, pure water, etc. can be used. Among them, pure water is preferably used. As the pure water, pure water generally used in industrial applications can be used.

In the drying treatment, either hot air drying or room temperature air drying can be used, and a drying method in which high-pressure air is blown from an air gun or a large amount of air is blown from a blower and water remaining on the surface of the solder resist layer is blown off with an air knife is preferable.

The features of the thin filming device created by this invention will be described in detail with the use of drawings. The device for thinning the solder resist layer in FIG. 5 has a pair of conveying rollers 6 that convey the substrate 3 on which the solder resist layer is formed. In the micelle removal processing unit 12, the micelle removal liquid supply spray nozzle 21 It is a fixed type, and is arranged so that the ejection direction is the same direction. The arrow 40 in the figure indicates the flow direction of the micelle removal liquid 10. In order to make it easier to understand the spray pattern 25 of the micellar removal solution 10, the upper micelle removal solution supply pipe 20 and the micelle removal solution supply spray nozzle 21 that should be provided are not shown.

FIG. 9 is a schematic diagram showing an example of the arrangement of the spray nozzle 21 for supplying micelle removal liquid in the thin film forming apparatus of the present invention. 9-1 is a state diagram when the flow of the micelle removal liquid supply spray nozzle 21 and the micelle removal liquid spray 22 inside the micelle removal processing unit 12 is observed from above the thinning device. 9-2 is a diagram showing the arrangement state of the spray nozzles 21 for the micelle removal liquid supply and the state of the micelle removal liquid spray 22 when viewed from the discharge side in the substrate conveying direction of the thin film forming apparatus. The arrow 44 in FIG. 9-1 indicates the conveyance direction of the substrate, and the arrow 43 indicates the spray direction of the spray nozzle for supplying the micelle removal liquid. In order to realize a state where all the micelle removal liquid flowing on the substrate 3 flows in the same direction, all the spray nozzles 21 for supplying the micelle removal liquid may be inclined in the same direction. In this state, when the substrate 3 being transported is viewed from above, the spray directions 43 of the spray nozzles for supplying all the micelle removal liquids face the same direction (FIG. 9-1 ). As described above, the micelle removal process is performed in a state where the spray nozzles 21 for the micelle removal liquid supply are inclined in the same direction so that the spray directions 43 of all the spray nozzles for the micelle removal liquid supply are in the same direction. As a result, the micelle removal liquid flow in the same direction can be sprayed toward the surface of the solder resist layer of the substrate 3 (Figure 9-2). In addition, in order to prevent the micelle removal liquid from flowing into the upstream equipment (thinning treatment unit 11) and the downstream equipment (water washing treatment unit 31) of the micelle removal processing unit 12 that performs the micelle removal treatment, it is preferable to supply the micelle removal liquid The spray direction 43 by the spray nozzle is unified to be inclined rightward or leftward orthogonal to the conveyance direction 44 of the substrate. As a result, the micelle removal liquid flows in the same direction from the upstream side of the spraying direction 43 of the spray nozzle for the micelle removal liquid supply to the downstream side (the flow direction of the micelle removal liquid 40), so the slow and uneven flow can be solved. The problem of unevenness in the amount of thinning of the solder resist layer in the surface of the substrate 3 caused by the liquid flow.

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 spraying direction 43 of the spray nozzle for supplying micelle removal liquid, a straight roller is used as the conveyance. The conveying roller 6 of the substrate 3. The surface of the straight roller has no unevenness and can be closely adhered to the surface of the solder resist layer. When the surface of the solder resist layer is in close contact with the straight rollers, the micelle removal liquid spray 22 can form a large flow of linear liquid flow between the paired conveying rollers 6 in the front and rear rows, and the liquid flow will not be disorderly. It becomes a turbulent flow and flows to the downstream side while following the conveying roller 6. Examples of the types of straight rollers include rubber rollers, sponge rollers, metal rollers, and resin rollers. Among them, olefin-based thermoplastic elastomer rolls are preferred, which have excellent rubber elasticity (sealing properties, recovery properties), small specific gravity, light weight, and hardness ranging from low to medium hardness due to contact with the solder resist layer The impact is small, and the chemical resistance is also excellent in the thin film treatment liquid which is a high-concentration alkaline aqueous solution. As the olefin-based thermoplastic elastomer, THERMORUN (registered trademark) can be cited.

In the spray pattern of the spray nozzle, there are solid cone, fan shape, linear shape, layered shape and so on. In this creation, since it is important to form the liquid flow in the same direction, the spray nozzle 21 for supplying micelle removal liquid is not a swing type or a swing type, but a fixed type. In addition, the fixed spray nozzles are sprayed obliquely in the same direction. When a fixed spray nozzle is used, in order to make the spray pattern always uniform, it is preferable to fix the inclination angle of the spray nozzle. In the method in which the spray nozzle 21 for supplying micelle removal liquid is directly attached to the supply tube 20 for micelle removal liquid at a desired inclination angle and fixed, there is no need to adjust the inclination angle when replacing the spray nozzle 21 for supplying micelle removal liquid. Therefore preferred. In addition to this, the following method may also be adopted. That is, a connector capable of adjusting the inclination angle (for example, manufactured by Ikeuchi Co., product name: UT Ball Joint) is installed in the micelle removal liquid supply pipe 20, and the micelle removal liquid is adjusted. The inclination angle of the spray nozzle 21 for supply is fixed.

In the thinning of the solder resist layer where the dissolution of micelles and the removal rate are extremely slow, if the spray pattern is a solid cone, the micelles cannot be completely removed and remain. This is because the basic compound required for the dissolution and removal of the insoluble micelles is eluted, so that the insoluble micelles are restored to the original state of the components of the solder resist layer. In this creation, when the spray pattern of the spray nozzle 21 for the micellar removal liquid supply is fan-shaped, the area of the spray pattern (spray range) is small compared to the case where the spray pattern is a solid cone, so it can be increased per unit area In addition, the spray pressure per unit area can be increased. That is, a strong impact can be provided in a short period of time, so while the elution of the alkaline compound from the insolubilized solder resist layer can be suppressed, the insolubilized micelles can be dissolved and removed at one stroke. There are fan-shaped spray patterns that are evenly distributed in all areas in the width direction; patterns that are distributed in a mountain shape that are strong at the center and weaker at the ends can be used.

The difference in the area of the spray pattern of a solid cone and a fan will be described. 11 is a schematic diagram showing the spray pattern of the micellar removal liquid, which is the arrangement state of the spray nozzle 21 for the micelle removal liquid supply when viewed from the discharge side of the substrate conveying direction of the thinning device, and viewed from above the thinning device The ejection state of the micelle removing liquid and the ejection range (spray pattern) of the micelle are shown in the state diagram. Compared with the spray pattern (solid cone) 24, the spray pattern (fan shape) 25 has a small area. Although this area changes with the supply flow rate, spray pressure, the distance from the surface of the solder resist layer, and the inclination angle 47 of the spray nozzle 21 for supplying micelle removal liquid, the area ratio of the sector to the solid cone (sector/solid cone ) About 15-20%.

The so-called solder resist with a very slow rate of dissolution and removal of micelles includes, for example, solder resists containing alkali-soluble resins with few free carboxyl groups, solder resists containing alkali-soluble resins with a large mass average molecular weight, and low-alkali-soluble resins and photopolymerizable. Solder resist with many compounds, etc.

In the solder resist layer thinning device of FIG. 6, in the micelle removal processing unit 12, the micelle removal liquid supply pipe 20 is arranged with the spray nozzle 21 for the micelle removal liquid supply relative to the conveying direction of the substrate 3, The front and back rows of the micelle removal liquid supply pipe 20 are staggered positions. Thereby, the spray position of the spray pattern 25 in the vertical direction of the conveyance direction of the substrate 3 can be equalized. In addition, in the water washing treatment unit 31, the arrangement of the spray nozzles 36 for the water washing treatment liquid supply of the water washing treatment liquid supply pipe 35 is staggered before and after the water washing treatment liquid supply pipe 35 with respect to the conveying direction of the substrate 3. The position can equalize the spray position of the spray pattern 38 in the direction perpendicular to the conveyance direction of the substrate 3.

In the apparatus for thinning the solder resist layer in FIG. 7, the micelle removal processing unit 12 is provided with a ring-shaped pair of conveying rollers 41. When the ring-shaped pair of conveying rollers 41 are used, the spray pattern 25 of the micelle removal liquid 10 spreads largely in the conveying direction of the substrate 3 between the pair of conveying rollers 41 in the front and rear rows. Therefore, it is difficult to form a large flow straight liquid flow compared with the straight cylindrical paired conveying rollers 4 shown in FIGS. 5 and 6. This shortcoming can be eliminated by the following operation, that is, in the range of not impairing the strength and durability of the toroidal roll, use a roll with a spoke or mesh roll, or a roll provided with through holes as the roll section. The ring-shaped conveying roller 41 allows the liquid flow from the upstream side to the downstream side in the ejection direction 43 to pass a certain amount. In addition, when the ring-shaped conveying roller 41 is used, it is only necessary to arrange the ring-shaped rollers at regular intervals in the vertical direction of the conveying direction of the substrate 3. In the staggered position, the interval between the conveying rollers 41 in the conveying direction of the substrate 3 can be equal to or less than the diameter of the ring rollers. As a result, the substrate 3 is prevented from falling during transportation, and there is an advantage that the substrate 3 with a thinner plate thickness can be transported. Examples of ring-shaped rollers include rubber rollers, sponge rollers, metal rollers, and resin rollers. Among them, polyethylene and polypropylene can be used which have a small specific gravity, light weight, less impact due to contact with the resist layer, and excellent chemical resistance in a thin film treatment liquid that is a high-concentration aqueous alkali solution. , Polycarbonate, polystyrene, rigid polyvinyl chloride, acrylic resin (PMMA), fluororesin (such as Teflon (TEFLON, registered trademark)), etc. In addition, rolls of olefin-based thermoplastic elastomers can also be used. As the olefin-based thermoplastic elastomer, THERMORUN (registered trademark) can be cited.

In the solder resist layer thinning device 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, in addition, the spray patterns 25 are arranged on a straight line in a direction perpendicular to the conveying direction of the substrate 3. The fan-shaped spray pattern 25 can adjust the spray direction by rotating the installation angle of the spray nozzle 21 for supplying micelle removal liquid. As a result, the high-pressure spray can be sprayed more efficiently to the solder resist layer on the substrate 3, and even when the amount of thinning is large, the insoluble solder resist layer can be removed without leaving any residue.

Example Hereinafter, an embodiment is used to further describe the creation in detail, but the creation is not limited to the embodiment.

(Example 1) For copper-clad laminates (area 170 mm×200 mm, copper foil thickness 18 μm, base material thickness 0.4 mm), dry-film solder resist (manufactured by Taiyo Ink Manufacturing Co., Ltd., trade name: PFR-800　AUS　SR1) Vacuum thermocompression bonding was performed on the above-mentioned circuit board (lamination temperature 75°C, suction time 30 seconds, pressing time 10 seconds) to form a solder resist layer with a film thickness of 30 μm.

Then, after peeling off the carrier film, a thin filming device including a solder resist layer of a thinning treatment unit 11 having a dipping tank 2 and a micelle removal treatment unit 12 for removing micelles with a micelle removal liquid 10 is used (FIG. 7 ), Thin the solder resist layer.

The spray nozzle 21 for supplying micelle removal liquid used is a fixed type, and the spray pattern 25 is fan-shaped. In addition, in Fig. 9-1 (a view of the state of the micelle removal liquid supply spray nozzle 21 and the micelle removal liquid spray 22 inside the micelle removal processing unit 12 viewed from above the thinning device), the micelle removal liquid The spraying directions 43 of the spray nozzles for supply are all facing the same direction. The arrangement state of the spray nozzles 21 for the micelle removal liquid supply and the micelle removal liquid when viewed from the discharge side of the substrate conveying direction of the thinning device in Fig. 9-2 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 is 25 degrees. That is, in the micelle removal processing unit 12, all the spray nozzles 21 for supplying micelle removal liquid are installed at an angle of 25 degrees to the left with respect to the conveying direction 44 of the substrate.

Use 10% by mass of sodium metasilicate (temperature 25°C) as the thin film treatment liquid 1, and perform the thin film treatment so that the immersion treatment time in the immersion tank 2 of the thin film treatment unit 11 is 30 seconds, and the solder resist The components of the layer are micellized. Thereafter, in the micelle removal processing unit 12, an aqueous solution of pH=8 (temperature 25°C) containing sodium metasilicate was used as the micelle removal liquid 10, and the micelle removal liquid supply spray nozzle 21 was supplied at a flow rate of 1.2 L/min is supplied to the substrate 3 to remove insoluble micelles and thin the solder resist layer. The supply flow rate of the micelle removal liquid per 1 cm ^{2 of the} solder resist layer was 0.10 L/min, and the spray pressure was 0.2 MPa. After that, water washing treatment and drying treatment are performed.

After the water washing treatment and the drying treatment, the thickness of the thinned portion of the solder resist layer was measured at 10 points. As a result, the maximum value was 16.0 μm, the minimum value was 14.0 μm, and the average thickness was 15.0 μm. In addition, the surface of the thinned solder resist layer was observed with an optical microscope, and it was confirmed that it was a smooth thinned surface without uneven processing.

(Example 2) The solder resist layer was thinned by the same method as in Example 1, except that the device for thinning the solder resist layer of FIG. 8 was used. In Embodiment 1, the spray pattern 25 is not arranged in a straight line in a direction perpendicular to the conveying direction of the substrate 3 (FIG. 7), while in Embodiment 2, the spray pattern 25 is arranged in a direction perpendicular to the conveying direction of the substrate 3. Arranged in a straight line in the direction (Figure 8). In addition, the inclination angle 47 formed by the vertical line 45 with respect to the substrate and the center line 46 of the spray nozzle is 25 degrees.

After the water washing treatment and the drying treatment, the thickness of the thinned part of the solder resist layer at 10 points was measured. As a result, the maximum value was 15.5 μm, the minimum value was 14.5 μm, and the average thickness was 15.0 μm. In addition, the surface of the thinned solder resist layer was observed with an optical microscope, and it was confirmed that it was a smooth thinned surface without uneven processing.

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

After the water washing treatment and the drying treatment, the thickness of the thinned part of the solder resist layer at 10 points was measured. As a result, the maximum value was 9.0 μm, the minimum value was 7.0 μm, and the average thickness was 8.0 μm. In addition, the surface of the thinned solder resist layer was observed with an optical microscope, and it was confirmed that it was a smooth thinned surface without uneven processing.

(Comparative example 1) The solder resist layer was thinned by the same method as in Example 1, except that the device for thinning the solder resist layer of FIG. 10 was used. That is, the spray nozzle 21 for supplying micelle removal liquid used is a fixed type, and its spray pattern 24 is a solid cone.

After the water washing treatment and the drying treatment, the thickness of the thinned part of the solder resist layer was measured at 10 points. As a result, the maximum value was 16.0 μm, the minimum value was 10.0 μm, and the average thickness was 13.0 μm. In addition, the surface of the thinned solder resist layer was observed with an optical microscope, and it was confirmed that there was no solder resist layer completely removed by the micelle removing liquid spray 22 remaining.

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

1: Thin film treatment liquid 2: Dipping tank 3: substrate 4: Conveying roller (straight cylinder type) 6: Conveyor roller (straight type) 7: Put in the mouth 10: Micellar removal liquid 11: Thin film processing unit 12: Micellar removal processing unit 13: Thin film treatment liquid storage tank 14: Thin film treatment liquid suction port 15: Thin film treatment liquid supply pipe 16: Thin film treatment liquid recovery pipe 17: Thin film treatment liquid discharge pipe 18: Micellar removal liquid storage tank 19: Micellar removal liquid suction port 20: Micellar removal liquid supply pipe 21: Spray nozzle for micellar removal liquid supply 22: Micelle removal liquid spray 23: Micellar removal liquid discharge pipe 24: Spray pattern (solid cone) 25: Spray pattern (fan shape) 31: Washing treatment unit 32: Washing treatment liquid 33: Conveying roller (ring type) 35: Water washing treatment liquid supply pipe 36: Spray nozzle for water washing treatment liquid supply 37: Water washing treatment liquid spray 38: Spray pattern (fan shape) 40: Flow direction of micellar removal liquid 41: Conveying roller (ring type) 43: Spray direction of the spray nozzle for the supply of micellar removal liquid 44: The conveying direction of the substrate 45: Vertical line relative to the substrate 46: Center line of spray nozzle 47: Tilt angle 51: Insulation layer 52: Conductor wiring 53: Solder resist layer 54: Bonding pad

FIG. 1 is an explanatory diagram showing a cross-sectional structure (SMD structure) of a solder resist pattern. FIG. 2 is an explanatory diagram showing a cross-sectional structure (NSMD structure) of a solder resist pattern. 3 is an explanatory diagram showing an example of a cross-sectional structure of a solder resist pattern formed by using the device for thinning a solder resist layer of the present invention. Fig. 4 is a schematic cross-sectional view showing a part of a device for thinning a solder resist layer. Fig. 5 is a schematic diagram showing an example of the device for thinning the solder resist layer of the present invention. Fig. 6 is a schematic diagram showing an example of the device for thinning the solder resist layer of the present invention. Fig. 7 is a schematic diagram showing an example of the device for thinning the solder resist layer of the present invention. Fig. 8 is a schematic diagram showing an example of the device for thinning the solder resist layer of the present invention. 9 is a schematic diagram showing an example of the arrangement of spray nozzles for micelle removal liquid supply in the device for thinning the solder resist layer of the present invention, in which FIG. 9-1 is a view of the spray nozzle for micelle removal liquid supply from above the thinning device Fig. 9-2 shows the state of the spray nozzles for the supply of micelle removal liquid and the spray state of the micelle removal liquid when viewed from the discharge side of the substrate conveying direction of the thinning device. picture. Fig. 10 is a schematic diagram showing an example of a device for thinning a solder resist layer outside of the present invention. FIG. 11 is a schematic diagram showing the spray pattern of the micelle removal liquid of the device for thinning the solder resist layer.

3: substrate

12: Micellar removal processing unit

20: Micellar removal liquid supply pipe

21: Spray nozzle for micellar removal liquid supply

22: Micelle removal liquid spray

43: Spray direction of the spray nozzle for the supply of micellar removal liquid

44: The conveying direction of the substrate

45: Vertical line relative to the substrate

46: Center line of spray nozzle

47: Tilt angle

Claims (2)

A device for thinning a solder resist layer includes a thin film processing unit that micellizes the components of the solder resist layer that has not been cured using a thin film processing liquid, and a micelle removal processing unit that removes micelles using a micelle removing liquid, It is characterized by The micelle removal processing unit has a spray nozzle for supplying micelle removal liquid, The spray nozzle for supplying the micelle removal liquid is a fixed type and is arranged so that the spray direction is the same direction, The spray pattern of the spray nozzle for supplying the micelle removal liquid is fan-shaped. The device for forming a thin film of a solder resist layer according to claim 1, wherein The spray nozzle for supplying the micelle removal liquid is arranged in a direction perpendicular to the conveying direction so that the spray pattern is aligned on a straight line.

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