JP4676317B2 - Resist pattern forming method, circuit board manufacturing method, and circuit board - Google Patents

Description

  The present invention relates to a resist pattern forming method, a circuit board manufacturing method, and a circuit board. More specifically, the present invention relates to a method for forming a resist pattern having a landless or narrow land width suitable for increasing the density of circuit boards and miniaturizing wiring patterns, a method for manufacturing circuit boards, and a circuit board.

  As electronic devices have become smaller and more multifunctional in recent years, the density of circuit boards and the miniaturization of wiring patterns have been promoted, and means for achieving such conditions include multilayering of circuit boards. As shown in FIG. 21, a multilayer circuit board formed by laminating a plurality of wiring layers generally has a through hole 31 in which an inner wall called a through hole is covered with a conductive layer or a through hole 31 filled with a conductive layer. There is continuity.

FIG. 22 is a schematic view of the through hole as viewed from above. A conductive layer called a land 18 is formed around the through hole 17. There are various types of lands, such as a square, a circle, an ellipse, and an irregular shape, but a circular land is often used because of the occupied area or the ease of use of the design surface. Further, in order to cope with higher density, a through hole having a landless or narrow land width is required. Here, in the case of a circular land, the land width means the minimum value of the annular conductor width around the through hole. When the diameter of the through hole at the time of drilling is D ₀ and the diameter of the circular conductor of the circular land is D, the landless is (D−D ₀ ) / 2 is zero, and the narrow land width is (D−D ₀ ) / 2 is greater than 0 and 40 μm or less.

  As a method for manufacturing a circuit board, a subtractive method, an additive method, and a semi-additive method are known. When a fine circuit is formed by the subtractive method, a thin line is generated by side etching of the conductive layer, which is disadvantageous for fine circuit formation. On the other hand, the additive method is advantageous for fine circuit formation, but has a problem of high manufacturing cost because all conductive layers are formed by electroless plating. The semi-additive method is multi-step, but can be used as a fine circuit forming method because it can use electrolytic plating capable of high-speed operation.

  An example of a method for manufacturing a circuit board by a semi-additive method will be given. First, a through hole 3 called a through hole is formed in the insulating substrate 1 (FIG. 23) (FIG. 24), and a thin first conductive layer 12 is provided on the surface including the inner wall of the through hole (FIG. 25). Next, a plating resist layer 36 is formed on the non-circuit portion (FIG. 26). Subsequently, the second conductive layer 13 is formed on the surface of the portion where the first conductive layer 12 is exposed by electrolytic plating (FIG. 27). Thereafter, the plating resist layer 36 is removed (FIG. 28), and the thin first conductive layer 12 below the plating resist layer 36 is removed by flash etching to form a circuit board (FIG. 29).

  The plating resist layer can be formed by a screen printing method, a photofabrication method having an exposure and development process using a photosensitive material, an ink jet method, or the like. Can be used preferentially. As a photofabrication method, a method using a negative type (photocrosslinking type) or a positive type (photolytic type) photoresist is generally used. In the semi-additive method, since the second conductive layer is provided on the inner wall of the through hole by electrolytic plating, it is necessary that the plating resist layer does not remain on the through hole and the inner wall of the through hole.

  When using a negative type (photocrosslinking type) dry film photoresist, as shown in FIG. 30, the through hole and the land part are shielded by the light shielding part 42, and the negative type (photocrosslinking type) dry film photoresist 38 is formed. It is made not to bridge | crosslink, an unreacted dry film photoresist is removed, and it is set as the state without a plating resist layer on a through-hole and a land part. In these processes, drilling of through holes and alignment of the exposure process are important, especially for landless and narrow land width through holes required for high-density circuit boards, extremely high alignment accuracy is required. Become.

  For example, as shown in FIG. 31 (b), when the land width is large, the through hole is completely shielded from light even if the positional deviation at the time of aligning the exposure mask occurs by the distance X. (Photocrosslinking type) Dry film photoresists are not crosslinked. However, as shown in FIG. 31 (a), in the case of a narrow land width, if the positional deviation at the time of aligning the exposure mask occurs by the same distance X, the through hole is detached from the land and covers the entire outer periphery of the through hole. There is a problem that a narrow land cannot be formed.

  When manufacturing a through-hole of a landless, as shown in FIG. 32, in order to widen the allowable range of alignment accuracy, only the central part on the through-hole of the negative (photocrosslinking type) dry film photoresist 38 is not exposed. As shown in FIG. 33, there is a known method for providing the light-shielding portion 42 and causing the plating resist layer 36 to protrude toward the center of the through hole (for example, Patent Document 1). As shown in FIG. 34B, in the case of the through hole 17 having a large hole diameter, even if the light shielding portion 42 is displaced by a distance Y, a part of the through hole 17 is shielded from light. However, as shown in FIG. 34A, in the case of a through hole having a small hole diameter, if the light shielding part 42 is displaced by the same distance Y, the light shielding part 42 is detached from the through hole 17. The upper negative (photo-crosslinking type) dry film photoresist 38 is cross-linked, which causes a problem that the plating resist layer 36 on the through hole is not removed.

  Actually, the alignment accuracy is limited due to the accuracy of drilling, expansion / contraction of the substrate, dimensional change of the photomask for exposure, and the like. Moreover, since the diameters of the through holes formed on the high-density circuit board are various and the number of holes is extremely large, it is very difficult to accurately align all the through holes. Therefore, even though a high-density circuit board requires a through-hole with a landless or narrow land width, in the case of a through-hole with a narrow land width, the through-hole is surely shielded and the negative type (optical In order to prevent the cross-linking type) dry film photoresist from cross-linking, there is a problem that the land width must be designed to be large (for example, Patent Document 2). In the case of a landless through-hole, the light-shielding portion must be designed to be small so that the light-shielding of the through-hole is reliably performed and the negative (photocrosslinking) dry film photoresist is not crosslinked. Therefore, there is a problem that the plating solution is difficult to penetrate into the through hole, and plating is not performed.

  As a method for forming a plating resist layer, a method using an electrodeposition photoresist is also known. This is a method of providing a plating resist layer by uniformly providing an electrodeposited photoresist layer on a conductive layer including an inner wall of a through hole by an electrodeposition coating method, and then exposing and developing through a photomask. It is.

  Electrodeposited photoresists include negative (photocrosslinking) and positive (photolytic). In the case of the positive type (photolytic type), it is necessary to expose and decompose the photoresist, but the inside of the through hole cannot be completely exposed with the cylindrical through hole. For this reason, the electrodeposition photoresist inside the through hole cannot be completely decomposed and cannot be used as a plating resist layer.

  On the other hand, in the case of a negative type (photo-crosslinking type) electrodeposited photoresist, it is not necessary to expose the inside of the through hole, so as a means for forming a landless through hole using a photomask having only a pattern without a land. It is said to be effective. Since light does not enter through the cylindrical through hole, the negative (photocrosslinking) photoresist layer on the inner wall of the through hole can be removed. However, when the corner portion of the through hole has a taper shape, there is a problem that light partially enters the inside of the through hole and the plating resist layer on the entire inner wall of the through hole cannot be removed. .

  Further, as a technique for solving these problems and forming a through hole having a narrow land width, a first resin layer is formed on a substrate having a through hole, and then a second resin is formed on the surface of the first resin layer other than on the through hole. Next, the first resin layer on the through hole is dissolved and removed using a first resin layer developer that does not dissolve the second resin layer, and the opening is accurately formed on the through hole. The technique is known (Patent Document 3). This technology makes it possible to accurately form through-holes with a narrow land width. On the other hand, when forming the second resin layer, equipment that is not used in conventional circuit board manufacturing methods such as a liquid toner developing device. Is newly required. Therefore, when there is no space for introducing new equipment or when equipment investment cannot be made, it is not possible to accurately form a through hole having a narrow land width.

Also, on the circuit board, in order to prevent solder from adhering to the land other than the pads necessary for soldering, the circuit layer conductive layer, etc., and to maintain the insulation of the circuit surface and protect the circuit unit conductive layer In general, a solder resist is coated on the surface of the substrate and filled in the through holes. At this time, if the shape of the top end portion of the land portion conductive layer is an acute angle, there is a problem that the thickness at the top end portion of the solder resist becomes extremely thin due to surface tension and curing shrinkage of the solder resist.
JP-A-10-178031 JP 07-007265 A International Publication No. 2005/085652 Pamphlet

  An object of the present invention is to provide a resist pattern forming method and a circuit board manufacturing method that can form a landless or narrow land-width through-hole without introducing new equipment, and can also provide a good solder resist. It is to provide a method and a circuit board, and in particular, to provide a resist pattern forming method, a circuit board manufacturing method, and a circuit board having a wide tolerance of alignment accuracy. In the present invention, the through-holes having a landless or narrow land width are as defined above.

As a result of intensive studies to solve the above problems, the present inventors have
(1) A step of forming a resin layer and a mask layer on a first surface of a substrate having a through-hole, and supplying a resin layer removing liquid from a second surface opposite to the first surface of the substrate, Removing the resin layer on the through-holes and the periphery of the through-holes, and a resist pattern forming method,
(2) The method for forming a resist pattern according to (1) above, wherein the resin layer and the mask layer are integrally formed,
(3) The method for forming a resist pattern according to the above (1) or (2), wherein the resin layer is a photocrosslinkable resin layer,
(4) The method for forming a resist pattern according to any one of (1) to (3) above, wherein the substrate having a through hole is an insulating substrate having a conductive layer on the substrate surface and the inner wall of the through hole.
(5) (a) preparing an insulating substrate having a first conductive layer on the first surface of the insulating substrate having a through hole, the second surface opposite to the first surface, and the inner wall of the through hole; ) A step of forming a photocrosslinkable resin layer and a mask layer on the first surface, and covering the first conductive layer and the through hole opening on the first surface with the photocrosslinkable resin layer and the mask layer; (c) the second surface Further, a photocrosslinkable resin layer removing liquid is supplied to remove the photocrosslinkable resin layer on the through hole on the first surface and the periphery of the through hole, and expose the first conductive layer on the periphery of the through hole on the first surface. (D) a step of pattern exposure of the photocrosslinkable resin layer on the first surface, (e) a photocrosslinkable resin layer and a mask layer are formed on the second surface, and the first conductive layer on the second surface and A step of covering the through-hole opening with a photocrosslinkable resin layer and a mask layer, (f) a step of removing the mask layer on the first surface, and (g) a photocrosslinkable resin layer removing solution from the first surface. The uncured photocrosslinkable resin layer on the first surface and the photocrosslinkable resin layer on the through hole on the second surface and around the through hole are removed, and the first conductive layer and the second on the first surface are removed. (H) a step of exposing the photocrosslinkable resin layer on the second surface by pattern exposure, (i) a step of removing the mask layer on the second surface, (j) ) Supplying a photocrosslinkable resin layer removing liquid from the second surface to remove the uncured photocrosslinkable resin layer on the second surface and exposing the first conductive layer on the second surface; (k) penetration Forming a second conductive layer by electrolytic plating on the inner wall of the hole and the periphery of the through hole, and on the first conductive layer exposed on the first surface and the second surface; (l) on the first surface and Removing the cured photocrosslinkable resin layer on the second surface to expose the first conductive layer on the first surface and the second surface; and (m) flashing the exposed first conductive layer. Method of manufacturing a circuit board comprising the step of removing by quenching, in this order,
(6) The method for manufacturing a circuit board according to (5), wherein the step (f) is performed before the step (e),
(7) The method for manufacturing a circuit board according to (5), wherein the step (f) is performed before the step (d),
(8) The step (g) includes (g1) supplying a photocrosslinkable resin removing liquid from the first surface to remove the uncured photocrosslinkable resin layer on the first surface, and the first conductivity on the first surface. A step of exposing the layer; and (g2) supplying a photocrosslinkable resin removing liquid from the first surface to remove the photocrosslinkable resin layer on the through hole on the second surface and in the periphery of the through hole, The method for manufacturing a circuit board according to claim 5, wherein the step (e) is performed between the step (g1) and the step (g2).
(9) From a land portion conductive layer formed in the periphery of the through hole of the insulating substrate having a through hole, a circuit portion conductive layer constituting circuit wiring on the surface of the insulating substrate, and a conductive layer on the inner wall of the through hole A circuit board, wherein the inclination angle of the outer surface of the land part conductive layer in the non-connection portion with the circuit part conductive layer is less than 90 degrees,
(10) The circuit board according to (9), wherein the inclination angle of the outer surface of the land portion conductive layer in the non-connection portion with the circuit portion conductive layer is 60 to 80 degrees,
(11) The circuit board according to (9) or (10), wherein the difference between the diameter of the outer surface of the land portion conductive layer and the diameter of the through hole at the time of drilling is 0 to 80 μm,
(12) The inclination angle of the outer surface of the land portion conductive layer in the non-connecting portion with the circuit portion conductive layer is smaller than the inclination angle of the side surface of the circuit portion conductive layer, according to any one of (9) to (11) above. Circuit board,
(13) The circuit board according to any one of (9) to (12), wherein an inclination angle of a side surface of the circuit unit conductive layer is approximately 90 degrees.
(14) The circuit board according to any one of (9) to (13), wherein the land part conductive layer is formed concentrically with respect to the through hole.
I found.

  In the resist pattern forming method (1) of the present invention, a resin layer and a mask layer are provided on one surface (first surface) of a substrate having a through hole so as to close the through hole, and the opposite surface (second surface and The resin layer on the through hole and in the periphery of the through hole is removed with the resin layer removing liquid supplied from step S1).

  The resin layer removing liquid supplied from the second surface passes through the through hole, reaches the resin layer on the first surface, and dissolves and removes the resin layer on the through hole and around the through hole. The mask layer is made of a component that is insoluble in the resin layer removing liquid. Therefore, the resin layer removing liquid can accurately and selectively remove only the through hole and the peripheral part of the through hole of the resin layer. As a result, the resin layer where the substrate is exposed can be formed with very high accuracy only in the through hole and the peripheral part of the through hole, and the landless and narrow land width patterns can be easily formed in the subsequent steps.

  In the resist pattern forming method (2) of the present invention, the process can be simplified by integrally forming the resin layer and the mask layer. Further, by forming a film in which a resin layer and a mask layer are laminated in advance and integrally forming the film on a substrate by means of lamination or the like, an extremely stable resist pattern forming method can be easily realized.

  In the resist pattern forming method (3) of the present invention, the resin layer is a photocrosslinkable resin layer. As a result, in addition to removing the resin layer on and around the through hole, it is possible to form a resist pattern by pattern exposure on the substrate surface, and the subsequent circuit pattern forming process on the through hole and substrate surface can be simplified. it can.

  In the method (4) for forming a resist pattern according to the present invention, a substrate having a through hole is an insulating substrate having a conductive layer on the surface and the inner wall of the through hole, thereby forming a more reliable circuit board. It is possible to form a resist pattern.

  In the circuit board manufacturing method (5) of the present invention, the photocrosslinkable resin layer and the mask layer are formed on the first surface of the insulating substrate having the first conductive layer on the surface and the inner wall of the through hole. Thereafter, the photocrosslinkable resin layer on the through hole and in the peripheral part of the through hole is removed by the photocrosslinkable resin layer removing liquid supplied from the second surface. Thereby, alignment is unnecessary and the 1st conductive layer of a through-hole and a through-hole periphery part can be exposed accurately. In addition, by controlling the removal method using the photocrosslinkable resin layer removing liquid, it is possible to control the removal status of the photocrosslinkable resin layer on the through hole and the periphery of the through hole, and the exposed width of the periphery of the through hole Can be controlled. Thereafter, the photocrosslinkable resin in the non-circuit portion is cured by pattern exposure on the photocrosslinkable resin layer on the first surface. Next, after a step of forming a photocrosslinkable resin layer and a mask layer on the second surface and a step of removing the mask layer on the first surface, a photocrosslinkable resin layer removing liquid is supplied from the first surface, The uncured photocrosslinkable resin layer on one surface and the photocrosslinkable resin layer on the through holes on the second surface and in the periphery of the through holes are removed. At this time, since the cured photocrosslinkable resin is insoluble in the photocrosslinkable resin layer removing liquid, a resist pattern of the cured photocrosslinkable resin is formed on the first surface. In the same manner for the second surface, the step of exposing the photocrosslinkable resin layer on the second surface to a pattern after exposing the through hole and the first conductive layer in the periphery of the through hole with high precision, and the mask layer on the second surface A step of removing, a step of supplying a photocrosslinkable resin layer removing liquid and a step of removing the uncured photocrosslinkable resin layer on the second surface, and curing that functions as a plating resist layer on both the first surface and the second surface It is possible to form a resist pattern made of the photocrosslinkable resin. Subsequently, a step of forming a second conductive layer on the exposed first conductive layer by electrolytic plating, a step of removing the first surface and the cured photocrosslinkable resin layer on the second surface, an exposed first conductive layer A circuit board having a landless or narrow land width is manufactured through a step of removing the layer by flash etching.

  Since both the first surface and the second surface are exposed before the step of pattern exposure of the photocrosslinkable resin layer, the through hole and the first conductive layer around the through hole are exposed. Even if the peripheral portion of the through hole is not exposed in the step of performing, a good land shape can be secured. In other words, the landless and narrow land widths can be accurately and reliably formed without aligning, and the excellent effect of widening the allowable range of alignment during pattern exposure is brought about.

  In the resist pattern forming method and the circuit board manufacturing method of the present invention, the removal amount of the photocrosslinkable resin layer is controlled in the step of removing the photocrosslinkable resin layer in the state having the mask layer. The width can be adjusted. Further, according to this method, the land around the through hole has a uniform width as shown in FIG.

  As described above, in the resist forming method and the circuit board manufacturing method of the present invention, the plating resist layer does not exist accurately and selectively with respect to the through-hole and the peripheral portion of the through-hole only by a process that does not require alignment. The state can be formed, and the excellent effect that the land width can be arbitrarily controlled is brought about.

  The circuit board (9) of the present invention includes a land part conductive layer formed in a peripheral part of a through hole of an insulating substrate having a through hole manufactured by the method for manufacturing a circuit board of the present invention, and a surface of the insulating substrate. The circuit board is composed of a circuit layer conductive layer constituting the circuit wiring and a conductive layer on the inner wall of the through hole, and the inclination angle of the outer surface of the land conductive layer at the non-connection portion with the circuit part conductive layer is 90 degrees. A smaller circuit board. Further, in the circuit boards (10) to (14) of the present invention, the inclination angle of the outer surface of the land portion conductive layer in the non-connection portion with the circuit portion conductive layer is 60 to 80 degrees, respectively. The circuit board according to (9) or (10) above, wherein the difference between the diameter of the outer surface of the land conductive layer and the diameter of the through hole at the time of drilling is 0 to 80 μm; The circuit board according to any one of the above (9) to (11), wherein an inclination angle of an outer side surface of the land portion conductive layer in a non-connecting portion with the conductive layer is smaller than an inclination angle of a side surface of the circuit portion conductive layer; The circuit board according to any one of the above (9) to (12), wherein the side surface of the conductive layer has an inclination angle of approximately 90 degrees; the land conductive layer is formed concentrically with respect to the through hole; (9) It is a circuit board in any one of (13). As a result, a circuit board having a landless or a land having a narrow land width can be realized, and in particular, there is an effect that the subsequent application of the solder resist can be performed extremely well.

  That is, on the circuit board, solder resist is used to prevent lands and circuit parts other than the pads necessary for soldering from being applied to the solder, and to maintain the insulation of the circuit surface and protect the conductor pattern. The substrate surface is covered, and a solder resist is filled in the through holes. At this time, since the shape of the top end portion of the land conductive layer is an obtuse angle larger than 90 degrees, the thickness at the top end portion of the solder resist becomes extremely thin due to surface tension and curing shrinkage of the solder resist. Good solder resist is imparted without the occurrence of. In general, the cross-sectional shape of the circuit portion conductive layer is considered to be rectangular in order to obtain a good signal transmission speed. In the conventional circuit board manufacturing method, it is difficult to make the shape of the top end portion of the land portion conductive layer obtuse while the shape of the circuit portion conductive layer is rectangular, but in the circuit board of the present invention, the circuit portion conductive layer While the cross-sectional shape of the layer is rectangular, that is, the inclination angle of the side surface of the circuit portion conductive layer is approximately 90 degrees, the shape of the top end portion of the land portion conductive layer is obtuse, that is, the inclination angle of the outer surface of the land portion conductive layer is 90 °. Can be smaller than degrees. As a result, not only the circuit board having a landless or narrow land width but also the problem that the thickness of the solder resist of the land portion becomes extremely thin due to the surface tension and the curing shrinkage of the solder resist can be avoided. There is an effect.

  Hereinafter, a resist pattern forming method, a circuit board manufacturing method, and a circuit board according to the present invention will be described in detail.

  In the resist pattern forming method, circuit board manufacturing method, and circuit board according to the present invention, as shown in FIG. 4, the resin layer 25 is formed so as to block the through hole on one side (first surface) of the substrate having the through hole. The mask layer 6 is provided, and the resin layer on the through hole in the first surface and around the through hole is removed by a resin layer removing liquid supplied from the surface opposite to the first surface (referred to as the second surface). FIG. 5).

  The resin layer according to the present invention is not particularly limited as long as it is a resin that can be dissolved and removed by the resin layer removing solution. Acrylic resin, vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, polyethylene, polypropylene and its chloride, polyester resin such as polyethylene terephthalate and polyethylene isophthalate, polyamide resin, vinyl modified alkyd Resins such as resin, phenol resin, xylene resin, polyimide resin, gelatin, and cellulose ester derivatives such as carboxymethyl cellulose can be used. Moreover, the photocrosslinkable resin described below can also be used as the resin layer. Even if these resins are the same type of resin, the solubility varies depending on the type and amount of the functional groups contained in the resin and the difference in molecular weight. When using an aqueous alkali solution as the resin layer removing solution, the resin layer removing solution can be dissolved and removed by using a resin having high solubility in the aqueous alkaline solution as the resin layer. When an aqueous alkali solution is used as the removing solution, a resin having an acid value of 1 mgKOH / g or more, more preferably 10 mgKOH / g or more can be suitably used as the resin layer. When an alkaline aqueous solution is used as a removing solution, the resin layer contains a monomer having a carboxylic acid group, a methacrylic acid amide, a phenolic hydroxyl group, a sulfonic acid group, a sulfonamide group, a sulfonimide group, or a phosphonic acid group. Examples thereof include a copolymer, a phenol resin, and a xylene resin. Specific examples include styrene / maleic acid monoalkyl ester copolymer, methacrylic acid / methacrylic acid ester copolymer, styrene / methacrylic acid / methacrylic acid ester copolymer, acrylic acid / methacrylic acid ester copolymer, Methacrylic acid / methacrylic acid ester / acrylic acid ester copolymer, styrene / methacrylic acid / acrylic acid ester copolymer, styrene / acrylic acid / methacrylic acid ester copolymer, vinyl acetate / crotonic acid copolymer, vinyl acetate / Crotonic acid / methacrylic acid ester copolymer, vinyl benzoate / acrylic acid / methacrylic acid ester copolymer such as styrene, acrylic ester, methacrylate, vinyl acetate, vinyl benzoate and the above carboxylic acid-containing monomer The copolymer of these is mentioned. These resins may be used alone or in combination of two or more. Moreover, if the solubility with respect to a removal liquid is ensured, another additive can also be added.

  Examples of the photocrosslinkable resin according to the present invention include a photocrosslinkable dry film photoresist for manufacturing a circuit board. Examples will be given below, but any photocrosslinkable resin layer can be applied as long as it does not differ from the gist of the present invention. For example, a negative photosensitive resin composition comprising a binder polymer containing a carboxylic acid group, a photopolymerizable polyfunctional monomer, a photopolymerization initiator, a solvent, and other additives can be used. Their blending ratio is determined in accordance with required properties such as sensitivity, resolution, hardness, tenting property and the like. Examples of these include “Photopolymer Handbook” (edited by Photopolymer Social Society, Kogyo Kenkyukai, 1989) and “Photopolymer Technology” (edited by Yamao Ao, Nagamatsu Mototaro, Nikkan Kogyo Shimbun, 1988). It is described in. As commercial products, for example, Liston from DuPont MRC Dry Film Co., Ltd., Fotec from Hitachi Chemical Co., Ltd., Sunfort from Asahi Kasei Electronics Co., Ltd. can be used. In the commercial product, the photocrosslinkable resin film is sandwiched between a support film such as a polyester film and a protective film such as a polyethylene film.

  As the mask layer according to the present invention, a resin or metal that is insoluble or hardly soluble in the resin layer removing solution or the photocrosslinkable resin layer removing solution can be used. As the resin, acrylic resin, vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin, vinyl acetal resin such as polyvinyl butyral, polystyrene, polyethylene, polypropylene and its chloride, polyester resin such as polyethylene terephthalate and polyethylene isophthalate, polyamide Resins such as resins, vinyl-modified alkyd resins, phenol resins, xylene resins, polyimide resins, gelatin, and cellulose ester derivatives such as carboxymethyl cellulose can be used. From the viewpoint of versatility, a polyester resin, a polyimide resin, or the like can be preferably used. Copper, aluminum, etc. can be used as a metal. When pattern exposure related to the formation of a resist pattern is performed through a mask layer, a resin having light transparency is used so that there is no obstacle to pattern exposure. If the mask layer is formed in a film shape and integrated with the resin layer on the substrate, it is preferable because the resin layer and the mask layer can be easily and stably formed in the process. When the above-mentioned dry film photoresist is used as the photocrosslinkable resin, the support film can be used as it is as a mask layer, which is preferable. Even if these resins are the same type of resin, the solubility varies depending on the type and amount of the functional groups contained in the resin and the difference in molecular weight. When using alkaline aqueous solution as a resin layer removal liquid, it becomes insoluble or hardly soluble in resin layer removal liquid by using resin with low solubility with respect to alkaline aqueous solution among these resins as a mask layer. In the case of using an alkaline aqueous solution as the removing solution, a resin having an acid value of the mask layer that is one-tenth or less, preferably one-hundredth or less of the acid value of the resin layer can be suitably used.

  The resin layer removal liquid or photocrosslinkable resin layer removal liquid (hereinafter collectively referred to as “removal liquid”) according to the present invention is a liquid that can dissolve or disperse the resin layer or the photocrosslinkable resin layer. The liquid suitable for the composition of the resin layer or photocrosslinkable resin layer to be used is used. The removal liquid removes the resin layer or the photocrosslinkable resin layer on the through hole and in the periphery of the through hole, thereby forming a region where the resin layer or the photocrosslinkable resin layer does not exist on the through hole and in the periphery of the through hole. The removal of the resin layer or the photocrosslinkable resin layer on the through hole means that at least a part of the resin layer or the photocrosslinkable resin layer immediately above the through hole is removed and an opening is formed on the through hole. State. In the opening of the resin layer or the photocrosslinkable resin layer, the opening diameter of these resin layers may be smaller than the diameter of the through hole. Even if the removal liquid is a liquid that does not dissolve the mask layer, or a liquid that dissolves the mask layer, the mask layer swells under conditions that dissolve the resin layer or the photocrosslinkable resin layer by an appropriate amount, Use liquid that does not change shape. In general, an alkaline aqueous solution is usefully used, for example, an aqueous solution of an inorganic basic compound such as alkali metal silicate, alkali metal hydroxide, phosphoric acid or alkali metal carbonate, phosphoric acid or ammonium carbonate, Organic basic compounds such as ethanolamine, ethylenediamine, propanediamine, triethylenetetramine and morpholine can be used. In order to control the solubility of these aqueous solutions in the resin layer or the photocrosslinkable resin layer, it is necessary to adjust the concentration, temperature, spray pressure, and the like. The removal liquid may be supplied by any method as long as the removal liquid can be supplied from the surface opposite to the surface having the mask layer through the through-hole so that the removal liquid is in contact with the resin layer or the photocrosslinkable resin layer. A dip treatment device, a double-sided shower spray device, a single-sided shower spray device, or the like can be used. The removal of the resin layer or the photocrosslinkable resin layer can be quickly stopped by washing with water or acid treatment following the treatment with the removing solution.

  As a method for integrally forming the resin layer or the photocrosslinkable resin layer and the mask layer according to the present invention, a dry film in which a resin layer or a photocrosslinkable resin layer is previously formed on a film support serving as a mask layer is used as a laminator. Thus, a method of laminating to a substrate can be suitably used.

  As the insulating substrate according to the present invention, a paper substrate phenol resin or glass substrate epoxy resin substrate, a polyester film, a polyimide film, a liquid crystal polymer film, or the like can be used. As the conductive layer, copper, silver, gold, aluminum, stainless steel, 42 alloy, nichrome, tungsten, ITO, conductive polymer, various metal complexes, and the like can be used. Examples of these are described in “Handbook of Printed Circuit Technology” (edited by Japan Printed Circuit Industry Association, Nikkan Kogyo Shimbun, 1987).

  As a method of providing the first conductive layer on the insulating substrate according to the present invention, a sputtering method, a vapor deposition method, an electroless plating method, a method of attaching an ultrathin conductive layer such as a metal foil to the insulating substrate, For example, there is a method of forming a thin film by etching the conductive layer of the laminated laminate. After the through hole is formed in the insulating substrate, the first conductive layer can be provided on the surface of the insulating substrate and the inner wall of the through hole, or after the first conductive layer is provided on the surface of the insulating substrate, the through hole is formed. You may make a hole and provide a 1st conductive layer in the surface and the inner wall of a through-hole again. The second conductive layer can be formed by an electrolytic plating method for the first conductive layer.

  For the electroless plating treatment and the electrolytic plating treatment according to the present invention, for example, those described in "Handbook of Printed Circuit Technology" (edited by Japan Printed Circuit Industry Association, Nikkan Kogyo Shimbun, 1987) should be used. Can do.

  In the circuit board manufacturing method (5) of the present invention, resist patterns are sequentially formed on both sides as follows, and a circuit board is manufactured by a semi-additive method. As a method for forming a resist pattern, any one of (1) to (4) of the present invention is used.

  First, the through hole 3 is formed in the insulating substrate 1 (FIG. 1) (FIG. 2). Next, the first conductive layer 12 is provided on the surface of the insulating substrate 1 and the inner wall of the through hole 3 (FIG. 3). Thereafter, the photocrosslinkable resin layer 25 is provided on the first surface so as to be tented in the through hole (FIG. 4). At that time, the mask layer 6 is formed on the photocrosslinkable resin layer 25 in contact with the photocrosslinkable resin layer 25. Next, a photocrosslinkable resin layer removing liquid is supplied from the second surface opposite to the first surface, and the photocrosslinkable resin layer 25 on and around the through holes on the first surface is dissolved and removed (FIG. 5). Photocrosslinkability on and around the through hole by adjusting the conditions of the removal process such as the type and concentration of the removal liquid, the time and temperature of the removal process, and the spray pressure and discharge rate of the removal liquid in the case of spraying. The removal amount of the resin layer 25 can be adjusted, and the exposed width of the first conductive layer can be controlled. Therefore, it is possible to control the land width thereafter from the landless to the narrow land and the wide land. If necessary, washing and drying are performed, and then pattern exposure is performed on the photocrosslinkable resin layer 25 on the first surface.

  Pattern exposure is performed by laser direct drawing, contact exposure through a photomask, proximity exposure, projection exposure, or the like. As the light source, in addition to various laser light sources, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like can be used. By this pattern exposure, the photocrosslinkable resin in the non-circuit portion is cured (FIG. 6).

  The photocrosslinkable resin layer 25 and the mask layer 6 are also formed on the second surface by the same method as that applied to the first surface (FIG. 7). After removing the mask layer 6 on the first surface (FIG. 8), the treatment with the photocrosslinkable resin layer removing liquid is performed again. The removal liquid is supplied from at least the first surface, and the uncured photocrosslinkable resin layer 25 on the surface of the first surface is dissolved and removed, and the light on the through holes on the second surface and the periphery of the through holes is passed through the through holes. The crosslinkable resin layer 25 is dissolved and removed (FIG. 9). At this time, similarly to the treatment of the first surface, the removal amount of the photocrosslinkable resin layer 25 on the through hole of the second surface and the peripheral portion of the through hole can be adjusted, and the exposed width of the first conductive layer 12 can be adjusted. Can be controlled. If necessary, the photocrosslinkable resin layer 25 on the second surface is subjected to pattern exposure to cure and dry the photocrosslinkable resin in the non-circuit portion (FIG. 10).

  If the removal of the mask layer on the first surface is after the step of removing the photocrosslinkable resin layer on the through hole on the first surface and in the periphery of the through hole, the photocrosslinkable resin layer and the mask layer on the second surface are removed. You may carry out before formation. If there is a possibility of damage or contamination of the first surface during the formation of the photocrosslinkable resin layer and the mask layer on the second surface, the first after the formation of the photocrosslinkable resin layer and the mask layer on the second surface. It is preferable to remove the mask layer on the surface because the first surface after pattern exposure can be protected by the mask layer. On the other hand, after the treatment of the photocrosslinkable resin layer removing liquid from the first surface, the mask layer is removed, and then drying, exposure, and the like can be performed. Further, after removing the uncured photocrosslinkable resin layer on the first surface, the photocrosslinkable resin layer and the mask layer on the second surface are formed, and then on the through holes on the second surface and the periphery of the through holes. The photocrosslinkable resin layer may be removed.

  After the pattern-exposed mask layer 6 on the second surface is removed (FIG. 11), a treatment with a photocrosslinkable resin layer removing solution is performed. The removal liquid is supplied at least from the second surface, and the uncured photocrosslinkable resin layer 25 on the surface of the second surface is dissolved and removed (FIG. 12).

  Thereby, the resist pattern which consists of the hardened | cured photocrosslinkable resin 26 which functions as a plating resist layer can be formed in a 1st surface and 2nd surface both surfaces. Next, the second conductive layer 13 is formed on the exposed first conductive layer 12 by electrolytic plating (FIG. 13), and then the cured photocrosslinkable resin layer 26 on the first surface and the second surface is removed ( 14), and the first conductive layer 12 that is exposed can be flash-etched to produce a circuit board having a landless or narrow land width (FIG. 15).

  In the method for producing a circuit board of the present invention, examples of a method for removing the cured photocrosslinkable resin layer used as the plating resist layer include a method for removing with a high pH alkaline aqueous solution, an organic solvent, and the like.

  The etchant used for flash etching of the first conductive layer according to the present invention may be any solution that can dissolve and remove the first conductive layer 12. For example, common etching solutions such as alkaline ammonia, sulfuric acid-hydrogen peroxide, cupric chloride, persulfate, and ferric chloride can be used. Moreover, as an apparatus and a method, apparatuses and methods, such as horizontal spray etching and immersion etching, can be used, for example. These details are described in “Printed Circuit Technology Handbook” (edited by Japan Printed Circuit Industry Association, Nikkan Kogyo Shimbun, 1987).

  FIG. 16 is a schematic plan view showing a land portion and a circuit portion of the circuit board of the present invention. The land portion conductive layer according to the present invention is a conductive layer forming a land, and is a region indicated by reference numeral “18” in FIG. Further, the circuit portion conductive layer according to the present invention is a conductive layer constituting wiring formed on the surface other than the through hole and the land, and is a region indicated by reference numeral “28” in FIG.

  Further, the non-connection portion of the land according to the present invention with the circuit portion conductive layer is a region of the land portion conductive layer that is not in contact with the circuit portion conductive layer.

  The inclination angle of the outer side surface of the land portion conductive layer and the inclination angle of the side surface of the circuit portion conductive layer according to the present invention will be described below with reference to FIGS.

  17A is a schematic cross-sectional view taken along line B in FIG. 16, and FIG. 18A is a schematic cross-sectional view taken along line C in FIG. FIG. 17A shows a cross section of the land portion conductive layer 18 that is not connected to the circuit portion conductive layer of the land, and the inclination angle α of the outer surface of the land portion conductive layer is the top of the land portion conductive layer. An angle formed by a line segment connecting the portion 18a and the land portion conductive layer bottom end portion 18b and the surface of the insulating substrate 1, and means an angle on the side sandwiching the conductive layer. Here, the land portion conductive layer bottom end portion 18b is an outer peripheral contour portion of the surface where the land portion conductive layer 18 is in contact with the insulating substrate 1, as shown in FIG.

  FIG. 18A shows a cross section of the circuit unit conductive layer 28. The inclination angle β of the side surface of the circuit unit conductive layer is defined as the circuit unit conductive layer top end portion 28a and the circuit unit conductive layer bottom end portion 28b. The angle formed by the connecting line segment and the surface of the insulating substrate 1 means the angle on the side sandwiching the conductive layer. Here, the circuit portion conductive layer bottom end portion 28b is a contour portion of the surface where the circuit portion conductive layer 28 is in contact with the insulating substrate 1, as shown in FIG.

  In FIG. 17, in addition to the case where the inclination angle α of the outer surface of the land portion conductive layer is smaller than 90 degrees (FIG. 17A), the inclination angle of the outer surface of the land portion conductive layer for comparison. When α is approximately 90 degrees (FIG. 17B), the cross section of the land conductive layer when the inclination angle α of the outer surface of the land conductive layer is greater than 90 degrees (FIG. 17C) is also shown. Yes. Also in FIG. 18, in addition to the case where the inclination angle β of the side surface of the circuit unit conductive layer is approximately 90 degrees (FIG. 18A), for the sake of comparison, the inclination angle β of the side surface of the circuit unit conductive layer is A cross section of the circuit portion conductive layer when the inclination angle β of the side surface of the circuit portion conductive layer is smaller than 90 degrees (FIG. 18C) when it is larger than 90 degrees (FIG. 18B) is also shown. Here, “approximately 90 degrees” refers to 85 to 95 degrees.

  In general, the cross-sectional shape of the circuit portion conductive layer is considered to be rectangular in order to obtain a good signal transmission speed. However, in the conventional circuit board manufacturing method, the shape of the circuit portion conductive layer is rectangular. However, it has been difficult to change the shape of the top end portion of the land portion conductive layer. However, in the circuit board of the present invention, as shown in FIG. 17A, the cross-sectional shape of the circuit part conductive layer is rectangular, that is, the inclination angle of the side surface of the circuit part conductive layer is approximately 90 degrees. On the other hand, the inclination angle α of the outer surface at the non-connection portion of the land portion conductive layer and the circuit portion conductive layer formed concentrically and continuously in the periphery of the through hole is made smaller than 90 degrees.

  That is, in the circuit board of the present invention, the inclination angle α of the outer surface of the land portion conductive layer 18 and the inclination angle β of the side surface of the circuit portion conductive layer 28 are different, and the inclination angle β of the side surface of the circuit portion conductive layer is approximately 90 degrees. In this circuit board, the inclination angle α of the outer surface of the land portion conductive layer is smaller than 90 degrees. By adopting the cross-sectional shapes of the land portion conductive layer 18 and the circuit portion conductive layer 28 of such a circuit board, the thickness at the top end portion of the solder resist is extremely caused by the surface tension and the curing shrinkage of the solder resist. The signal transmission speed of the circuit layer conductive layer can be kept good while having a favorable effect that a good solder resist can be applied without causing the problem of thinning. The inclination angle α of the outer surface of the land portion conductive layer is preferably in the range of 30 degrees to 80 degrees, and more preferably in the range of 60 degrees to 80 degrees.

  The inclination angle α of the outer surface of the land portion conductive layer varies depending on the thickness of the photocrosslinkable resin layer and the removal condition of the photocrosslinkable resin layer with the photocrosslinkable resin layer removing liquid, in addition to the plating thickness by electrolytic plating. For example, if the removal conditions of the photocrosslinkable resin layer are the same, the inclination angle α of the outer surface of the land portion conductive layer decreases as the plating thickness by electrolytic plating increases. If the removal conditions for the photocrosslinkable resin layer are the same, the inclination angle α of the outer surface of the land portion conductive layer becomes smaller as the photocrosslinkable resin layer is thicker. However, optimization of the removal conditions for the photocrosslinkable resin layer is also effective in reducing the inclination angle α of the outer surface of the land conductive layer. When the removal by the photocrosslinkable resin layer removing liquid is increased to widen the land width, the inclination angle of the outer surface of the land portion conductive layer increases and changes in a direction approaching 90 degrees. The inclination angle α of the outer surface of the land portion conductive layer becomes small. As described above, the removal amount of the photocrosslinkable resin layer is adjusted by adjusting the removal treatment conditions such as the type and concentration of the removal solution, the removal treatment time and temperature, and the spray pressure of the removal solution and the discharge amount when using the spray. Control. By forming the landless or narrow land width by the circuit board manufacturing method of the present invention, a circuit board having a good inclination angle of the outer surface of the land portion conductive layer can be obtained. In the method for producing a circuit board of the present invention, the removal condition of the resin layer or the photocrosslinkable resin layer depends on the thickness of these resin layers. For example, when the thickness of the photocrosslinkable resin layer is 20 to 30 μm The preferable removal conditions are a 1% by mass sodium carbonate solution as the removal solution, a removal temperature of 30 ° C., a treatment time of 20 to 60 seconds, and a spray pressure of 0.1 to 0.3 MPa.

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

  A glass substrate epoxy resin substrate (area 340 mm x 510 mm, substrate thickness 0.1 mm) is drilled with a 0.1 mmφ through-hole using a drilling machine, then desmeared, and then electroless plated. Then, an electroless copper plating layer having a thickness of about 0.5 μm was provided as a first conductive layer on the surface including the inner wall of the through hole. Using a laminator for dry film photoresist, a dry film photoresist for circuit formation consisting of a 25 μm photocrosslinkable resin layer and a 12 μm mask layer (support film, material: polyester) is applied to one side (first side and And a photo-crosslinkable resin layer and a mask layer (support film).

  Next, using a 1% by mass aqueous solution of sodium carbonate (30 ° C.), shower spray was applied for 32 seconds from the second surface side of the substrate at a spray pressure of 0.2 MPa, and the first surface was penetrated on and through the through holes. The photocrosslinkable resin layer around the hole was dissolved and removed. When the through hole and the periphery of the through hole were observed with an optical microscope, the photocrosslinkable resin layer in the periphery of the through hole was removed concentrically with the through hole. The various parameters for the through-hole shown in FIG. 19 are as follows: through-hole diameter L1 = 100 μm during drilling, through-hole diameter L2 = 99 μm during plating, photocrosslinkable resin layer removal portion diameter L3 = 139 μm, photocrosslinkable resin The diameter L4 at the top of the layer was 121 μm. In addition, the diameter L3 of the photocrosslinkable resin layer removing portion is measured by the opening diameter at the portion where the photocrosslinkable resin layer is in contact with the first conductive layer, and the diameter L4 above the photocrosslinkable resin layer is the photocrosslinkable resin. The opening at the part where the layer was in contact with the mask layer was measured.

  A photomask (conductor width and gap: 35 μm) on which a circuit pattern is drawn is placed on the first surface of the substrate, and a high pressure mercury lamp light source device for printing (Unirec URM300, manufactured by Ushio Inc.) having a suction adhesion mechanism is used for 30 seconds. Pattern exposure was performed.

  Next, using the dry film photoresist laminator on the second surface of the substrate after the exposure processing, the same circuit forming dry film photoresist as that on the first surface is thermocompression-bonded to form a photocrosslinkable resin layer and a mask. A layer was provided. Thereafter, the mask layer on the first surface was peeled off and removed.

  Next, using a removing solution of 1% by mass sodium carbonate aqueous solution (30 ° C.), shower spray was applied for 33 seconds from the first surface side of the substrate at a spray pressure of 0.2 MPa to form a photocrosslinkable resin layer on the first surface. The uncured portion was removed, and the photocrosslinkable resin layer on the through hole on the second surface and in the periphery of the through hole was dissolved and removed. When the through hole on the second surface and the periphery of the through hole were observed with an optical microscope, the photocrosslinkable resin layer in the periphery of the through hole was removed concentrically with the through hole. The through-hole diameter L1 at the time of drilling was 100 μm, the through-hole diameter L2 at the time of plating was 99 μm, the diameter L3 of the photocrosslinkable resin layer removal portion was 139 μm, and the upper diameter L4 of the photocrosslinkable resin layer was 121 μm.

  A photomask (conductor width and gap: 35 μm) on which a circuit pattern is drawn is placed on the second surface of the substrate, and a high pressure mercury lamp light source device for baking (Unirec URM300, manufactured by USHIO) is used for 30 seconds with ultraviolet light. Pattern exposure was performed. Thereafter, the mask layer on the second surface was peeled off and removed.

  Next, using a 1% by mass aqueous solution of sodium carbonate (30 ° C.), a shower spray was applied for 25 seconds from the second surface side of the substrate at a spray pressure of 0.2 MPa, and the photocrosslinkable resin layer on the second surface The part of was removed.

  As a result of observing the resist pattern made of the photocrosslinkable resin on the first surface and the second surface, a resist pattern is formed in the through hole and the periphery of the through hole so that the first conductive layer is accurately exposed concentrically. The resist pattern on the substrate surface was also formed well.

  Next, electrolytic copper plating was performed to form an electrolytic copper plating layer having a thickness of about 12 μm on the first conductive layer as the second conductive layer. Then, it processed with 3 mass% sodium hydroxide aqueous solution, and peeled and removed the bridge | crosslinking part of the photocrosslinkable resin used as a plating resist layer.

  Furthermore, it processed with the sulfuric acid-hydrogen peroxide type etching liquid (Mitsubishi Gas Chemical make, product name CPE, 30 degreeC, spray pressure 0.2MPa), and the exposed 1st conductive layer was removed. When the obtained circuit board was observed with an optical microscope, the lands were formed concentrically with the through holes. The through hole diameter L5 after flash etching shown in FIG. 20 was 76 μm, the land diameter L6 was 138 μm, and the land width was 19 μm. There was no disconnection in the circuit board, and a circuit board with a good narrow land width could be produced. In addition, when the solder resist was applied to the circuit board, the solder resist was satisfactorily applied without causing the problem that the thickness of the solder resist becomes extremely thin at the top end portion of the land conductive layer. It was broken.

  Further, the cross section of the circuit board was observed and the land diameter was examined in detail. As a result, the land diameter L6 at the land end at the bottom of the land (contact surface with the insulating substrate) was 138 μm. The land diameter L7 at the top end of the land at the top (the contour of the highest portion of the land portion conductive layer) was 129 μm, and the inclination angle α of the outer surface of the land portion conductive layer was 70 degrees. The cross-sectional shape of the circuit part conductive layer was 34 μm for both the top line width and the bottom line width of the wiring, and the inclination angle β of the side surface of the circuit part conductive layer was 90 degrees.

  In Example 1, when removing the photocrosslinkable resin layer on the through-holes on the first surface and the second surface and around the through-holes, a removal solution of 1% by mass sodium carbonate aqueous solution (30 ° C.) was used. A circuit board was fabricated in the same manner as in Example 1 except that the processing time was set to 26 seconds on the first surface and 28 seconds on the second surface.

  When the through hole just before electrolytic copper plating and the peripheral part of the through hole were observed with an optical microscope on each of the first and second surfaces, the photocrosslinkable resin layer on the peripheral part of the through hole was removed concentrically with the through hole. The through hole diameter L1 at the time of drilling is 100 μm, the through hole diameter at the time of plating is L2 = 99 μm, the diameter L3 of the photocrosslinkable resin layer removal portion is 115 μm, and the diameter L4 of the upper portion of the photocrosslinkable resin layer is 86 μm. It was.

  The same processing as in Example 1 was performed, and the circuit board obtained after the flash etching treatment was observed with an optical microscope. The lands were removed concentrically with the through holes, and the through hole diameter L5 after flash etching was 76 μm. The land diameter L6 = 114 μm and the land width was 7 μm. There was no disconnection in the circuit board, and a circuit board with a good narrow land width could be produced. In addition, when the solder resist was applied to the circuit board, the solder resist was satisfactorily applied without causing the problem that the thickness of the solder resist becomes extremely thin at the top end portion of the land conductive layer. It was broken.

  Further, the cross section of the circuit board was observed and the land diameter was examined in detail. As a result, the land diameter L6 at the land end portion at the bottom of the land (contact surface with the insulating substrate) was 114 μm. The land diameter L7 at the top end of the land at the top (the contour of the highest portion of the land conductive layer) was 100 μm, and the inclination angle α of the outer surface of the land conductive layer was 60 degrees. The cross-sectional shape of the circuit part conductive layer was 34 μm for both the top line width and the bottom line width of the wiring, and the inclination angle β of the side surface of the circuit part conductive layer was 90 degrees.

  In Example 1, when removing the photocrosslinkable resin layer on the through-holes on the first surface and the second surface and around the through-holes, a removal solution of 1% by mass sodium carbonate aqueous solution (30 ° C.) was used. A circuit board was fabricated in the same manner as in Example 1 except that the processing time was set to be as long as 50 seconds for both the first and second surfaces.

  When the through hole just before electrolytic copper plating and the peripheral part of the through hole were observed with an optical microscope on each of the first and second surfaces, the photocrosslinkable resin layer on the peripheral part of the through hole was removed concentrically with the through hole. The through hole diameter L1 at the time of drilling processing is 100 μm, the through hole diameter L2 at the time of plating processing is 99 μm, the diameter L3 of the photocrosslinkable resin layer removal portion is 149 μm, and the upper diameter L4 of the photocrosslinkable resin layer is 140 μm. It was.

  The same processing as in Example 1 was performed, and the circuit board obtained after the flash etching treatment was observed with an optical microscope. The lands were removed concentrically with the through holes, and the through hole diameter L5 after flash etching was 76 μm. The land diameter L6 = 148 μm and the land width was 24 μm. There was no disconnection in the circuit board, and a circuit board with a good narrow land width could be produced. In addition, when the solder resist was applied to the circuit board, the solder resist was satisfactorily applied without causing the problem that the thickness of the solder resist becomes extremely thin at the top end portion of the land conductive layer. It was broken.

  Further, the cross section of the circuit board was observed and the land diameter was examined in detail. As a result, the land diameter L6 at the end of the land at the bottom of the land (contact surface with the insulating substrate) was 148 μm. The land diameter L7 at the top end of the land at the top (the contour of the highest portion of the land conductive layer) was 144 μm, and the inclination angle α of the outer surface of the land conductive layer was 80 degrees. The cross-sectional shape of the circuit part conductive layer was 34 μm for both the top line width and the bottom line width of the wiring, and the inclination angle β of the side surface of the circuit part conductive layer was 90 degrees.

  In Example 1, using a dry film photoresist for circuit formation composed of a 40 μm photocrosslinkable resin layer and a 12 μm mask layer (support film, material: polyester), on the through holes on the first surface and the second surface, When dissolving and removing the photocrosslinkable resin layer around the through-hole, the treatment time using the removal solution of 1% by mass sodium carbonate aqueous solution (30 ° C.) was set to 88 seconds for both the first and second surfaces. A circuit board was produced in the same manner as in Example 1 except for the above point.

  When the through hole just before electrolytic copper plating and the peripheral part of the through hole were observed with an optical microscope on each of the first and second surfaces, the photocrosslinkable resin layer on the peripheral part of the through hole was removed concentrically with the through hole. The through hole diameter L1 at the time of drilling is 100 μm, the through hole diameter L2 at the time of plating is 99 μm, the diameter L3 of the photocrosslinkable resin layer removal portion is 181 μm, and the diameter L4 of the upper part of the photocrosslinkable resin layer is 166 μm. It was.

  The same processing as in Example 1 was performed, and the circuit board obtained after the flash etching treatment was observed with an optical microscope. The lands were removed concentrically with the through holes, and the through hole diameter L5 after flash etching was 76 μm. The land diameter L6 = 180 μm and the land width was 40 μm. There was no disconnection in the circuit board, and a circuit board with a good narrow land width could be produced. In addition, when the solder resist was applied to the circuit board, the solder resist was satisfactorily applied without causing the problem that the thickness of the solder resist becomes extremely thin at the top end portion of the land conductive layer. It was broken.

  Further, the cross section of the circuit board was observed and the land diameter was examined in detail. As a result, the land diameter L6 at the land end at the bottom of the land (contact surface with the insulating substrate) was 180 μm, The land diameter L7 at the top end of the land at the top (the contour of the highest portion of the land conductive layer) was 176 μm, and the inclination angle α of the outer surface of the land conductive layer was 80 degrees. The cross-sectional shape of the circuit part conductive layer was 34 μm for both the top line width and the bottom line width of the wiring, and the inclination angle β of the side surface of the circuit part conductive layer was 90 degrees.

  The present invention can be used for manufacturing circuit boards such as printed wiring boards and semiconductor devices.

Sectional drawing which shows 1 process in the method of this invention. Sectional drawing which shows the process following FIG. 1 in the method of this invention. Sectional drawing which shows the process following FIG. 2 in the method of this invention. Sectional drawing which shows the process following FIG. 3 in the method of this invention. Sectional drawing which shows the process following FIG. 4 in the method of this invention. Sectional drawing which shows the process following FIG. 5 in the method of this invention. Sectional drawing which shows the process following FIG. 6 in the method of this invention. Sectional drawing which shows the process following FIG. 7 in the method of this invention. Sectional drawing which shows the process following FIG. 8 in the method of this invention. Sectional drawing which shows the process following FIG. 9 in the method of this invention. Sectional drawing which shows the process following FIG. 10 in the method of this invention. Sectional drawing which shows the process following FIG. 11 in the method of this invention. Sectional drawing which shows the process following FIG. 12 in the method of this invention. Sectional drawing which shows the process following FIG. 13 in the method of this invention. Sectional drawing which shows the process following FIG. 14 in the method of this invention. The top view showing the hole land part of the circuit board of this invention. Sectional drawing in the line B part of FIG. FIG. 17 is a cross-sectional view taken along line C in FIG. 16. Sectional drawing which shows the through-hole diameter at the time of drilling in the method of this invention, the through-hole diameter at the time of metal-plating, and the diameter of a photocrosslinkable resin layer removal part. Sectional drawing showing the hole land part of the circuit board of this invention. 1 is a schematic cross-sectional view showing an example of a multilayer circuit board. Schematic plan view showing through holes and lands Sectional drawing which shows 1 process in the manufacturing method of the circuit board by a semi-additive method. FIG. 24 is a cross-sectional view showing a step following FIG. 23 in the method for manufacturing a circuit board by a semi-additive method. Sectional drawing which shows the process following FIG. 24 in the manufacturing method of the circuit board by a semi-additive method. FIG. 26 is a cross-sectional view showing a step following FIG. 25 in the method for manufacturing a circuit board by a semi-additive method. FIG. 27 is a cross-sectional view showing a step following FIG. 26 in the method for manufacturing a circuit board by a semi-additive method. FIG. 28 is a cross-sectional view showing a step following FIG. 27 in the method for manufacturing a circuit board by a semi-additive method. FIG. 29 is a cross-sectional view showing a step following FIG. 28 in the method for manufacturing a circuit board by a semi-additive method. Sectional drawing which shows an exposure process in the manufacturing method of the circuit board using the photocrosslinking type dry film photoresist which is a prior art. Schematic showing the positional deviation of a through-hole and a land. Sectional drawing which shows an exposure process in the manufacturing method of the circuit board using the photocrosslinking type dry film photoresist which is a prior art. Sectional drawing which shows 1 process in the manufacturing method of the circuit board using the photocrosslinking type dry film photoresist which is a prior art. Schematic showing the position shift of a through-hole and a photomask light-shielding part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Conductive layer 3 Through-hole 6 Mask layer 12 1st conductive layer 13 2nd conductive layer 17 Through-hole 18 Land part conductive layer 18a Land part conductive layer top end part 18b Land part conductive layer bottom end part 25 Photocrosslinkability Resin layer 26 Cross-linked portion 28 Circuit portion conductive layer 28a Circuit portion conductive layer top end portion 28b Circuit portion conductive layer bottom end portion 31 Through hole 36 Plating resist layer 38 Dry film photoresist 41 Photomask 42 Light shielding portion

Claims (10)

(A) preparing an insulating substrate having a first conductive layer on a first surface of the insulating substrate having a through hole, a second surface opposite to the first surface, and an inner wall of the through hole;
(B) forming a photocrosslinkable resin layer and a mask layer on the first surface, and covering the first conductive layer and the through hole opening on the first surface with the photocrosslinkable resin layer and the mask layer;
(C) The photocrosslinkable resin layer removing liquid is supplied from the second surface to remove the photocrosslinkable resin layer on the through hole on the first surface and the peripheral portion of the through hole, and on the peripheral portion of the through hole on the first surface. Exposing the first conductive layer;
(D) pattern exposing the photocrosslinkable resin layer on the first surface;
(E) forming a photocrosslinkable resin layer and a mask layer on the second surface, and covering the first conductive layer and the through hole opening on the second surface with the photocrosslinkable resin layer and the mask layer;
(F) removing the mask layer on the first surface;
(G) A photocrosslinkable resin layer removing liquid is supplied from the first surface, and the uncured photocrosslinkable resin layer on the first surface and the photocrosslinkable resin layer on the through holes on the second surface and around the through holes are provided. Removing the first conductive layer on the first surface and exposing the first conductive layer around the through hole on the second surface;
(H) pattern exposing the photocrosslinkable resin layer on the second surface;
(I) removing the mask layer on the second surface;
(J) supplying a photocrosslinkable resin layer removing liquid from the second surface, removing the uncured photocrosslinkable resin layer on the second surface, and exposing the first conductive layer on the second surface;
(K) forming a second conductive layer by electrolytic plating on the inner wall of the through hole and the periphery of the through hole, and the first conductive layer exposed on the first surface and the second surface;
(L) removing the cured photocrosslinkable resin layer on the first surface and the second surface to expose the first conductive layer on the first surface and the second surface;
(M) A method of manufacturing a circuit board, which includes a step of removing the exposed first conductive layer by flash etching in this order. (F) performed before step (e) a step method of manufacturing a circuit board according to claim 1, wherein. (F) performed before step (d) is step method of manufacturing a circuit board according to claim 1, wherein. (G) The step (g1) supplies a photocrosslinkable resin removing liquid from the first surface, removes the uncured photocrosslinkable resin layer on the first surface, and exposes the first conductive layer on the first surface. And (g2) supplying a photocrosslinkable resin removing liquid from the first surface to remove the photocrosslinkable resin layer on and around the through holes on the second surface, It consists of a step of exposing the first conductive layer in the peripheral portion, (e) performing step a (g1) between the step and (g2) process, a manufacturing method of a circuit board according to claim 1, wherein. It is manufactured by the method for manufacturing a circuit board according to claim 1,
A circuit board comprising: a land portion conductive layer formed around a through hole of an insulating substrate having a through hole; a circuit portion conductive layer constituting circuit wiring on the surface of the insulating substrate; and a conductive layer on the inner wall of the through hole A circuit board in which the inclination angle of the outer surface of the land portion conductive layer in the non-connection portion with the circuit portion conductive layer is smaller than 90 degrees. The circuit board according to claim 5 , wherein an inclination angle of an outer surface of the land portion conductive layer in a non-connection portion with the circuit portion conductive layer is 60 to 80 degrees. The circuit board according to claim 5 or 6 , wherein a difference between a diameter of the outer surface of the land portion conductive layer and a diameter of the through hole at the time of drilling is 0 to 80 µm. The circuit board according to any one of claims 5 to 7 , wherein an inclination angle of an outer surface of the land portion conductive layer in a non-connecting portion with the circuit portion conductive layer is smaller than an inclination angle of a side surface of the circuit portion conductive layer. The circuit board according to any one of claims 5 to 8 , wherein an inclination angle of a side surface of the circuit part conductive layer is approximately 90 degrees. Land portion conductive layer is formed concentrically with respect to the through-holes, the circuit board of any one of claims 5-9.

Images