JP5537476B2 - Method for producing conductive pattern - Google Patents

Description

  The present invention relates to a method for producing a conductive pattern by a subtractive method.

  As a method of manufacturing printed wiring boards and lead frames, an etching resist layer is provided on an insulating substrate having a conductive layer on the surface or a circuit portion of the conductive substrate, and the exposed conductive layer of the non-circuit portion is removed by etching. There is a subtractive method for forming a conductive pattern. In addition, there are an additive method and a semi-additive method in which a conductive layer is provided on a circuit portion of an insulating substrate by a plating method.

  As electronic devices have become smaller and more multifunctional in recent years, printed wiring boards and lead frames used inside devices are also becoming increasingly dense and conductive patterns are being refined. A conductive pattern having a conductor width of less than 50 to 80 μm and a conductor gap of 50 to 80 μm is manufactured. In addition, with higher density and finer wiring, ultrafine conductive patterns with a conductor width or conductor gap of less than 50 μm have been required. Along with this, the requirements for the accuracy and impedance of the conductive pattern are also increasing. In order to form such a fine conductive pattern, a semi-additive method has been studied instead of the subtractive method. However, there are problems such as a significant increase in the manufacturing process and insufficient adhesive strength of electrolytically plated copper. There was a problem. For this reason, the production of printed wiring boards and lead frames by the subtractive method has become the mainstream.

  In the subtractive method, the etching resist layer is formed by a photofabrication method, a screen printing method, an ink jet method or the like having an exposure and development process using a photosensitive material. Among these, the method using a sheet-like photocrosslinkable resin layer called a negative dry film resist in the photofabrication method is preferably used because it is easy to handle and can protect through holes by tenting. It has been.

  In the method using a photocrosslinkable resin layer, a photocrosslinkable resin layer is formed on a substrate, and an etching resist layer is formed through an exposure development process. In order to form a fine conductive pattern, it is indispensable to form a fine etching resist layer. For this reason, it is necessary to make the resist film thickness as thin as possible. For dry film resists that are common as photocrosslinkable resin layers, for example, if the film thickness is 10 μm or less, the resist layer may be peeled off or disconnected due to the inclusion of bubbles with dust as a core and the decrease in follow-up of unevenness. It is difficult to form a fine etching resist layer.

  In order to solve such problems, a dry film resist having a thickness of 25 μm or more is pasted on the substrate, and then the dry film resist is thinned to about 10 μm using an alkaline aqueous solution, and then exposure and development of a circuit pattern are performed. There has been proposed a method of forming an etching resist layer by performing (see, for example, Patent Document 1).

  In addition, after the photocrosslinkable resin layer on and around the hole is cured in advance, the photocuring resin layer on the uncured part is thinned to provide a tenting strength on the hole and the surrounding area. A thick etching resist layer can be formed, and the tenting film is hardly broken in the etching process, and the conductive layer in the hole is hardly etched. Further, a fine conductive pattern can be produced by exposing and etching a circuit pattern in a portion that is not necessary for tenting on and around the hole after thinning. According to this method, both the protection of the conductive layer in the hole by tenting and the production of a fine conductive pattern by the thinning process can be achieved without requiring a special dry film resist.

  However, the photocrosslinkable resin layer corresponding to and around the hole is often only a few percent to a dozen percent of the total area of the substrate, and most of the photocrosslinkable resin layer after the thinning treatment is bare. It has become. In this state, if normal handling is performed after thinning, contact with the exposure apparatus stage during double-sided exposure, contact between substrates, contact with a conveyor or suction pad during the transport process, loading and receiving processes, thinning the film Small dents called scratches or dents are generated in the resin layer, and defects that lead to chipping or disconnection of the resist pattern may occur.

  Further, in Patent Document 1, after the photocrosslinkable resin layer on and around the hole is previously cured, the photocrosslinkable resin layer in the uncured portion is thinned, and then the photocrosslinkable resin layer is formed. Although a method of re-laminating a transparent film has also been proposed, it is extremely difficult to completely follow the step of the photocrosslinkable resin layer with a normal transparent film. There have been cases where problems such as defects, film loss due to polymerization inhibition, or deterioration in resolution may occur.

  Further, in the method of precuring the photocrosslinkable resin layer on and around the hole, a step of curing the photocrosslinkable resin layer on and around the hole and a photocrosslinkable resin layer corresponding to a circuit pattern after thinning treatment There are two curing steps, the step of curing. In the curing of the photocrosslinkable resin layer, a through hole formed in the substrate is usually used as a reference (alignment mark) for the exposure position. However, when the through-hole used as an alignment mark in the step of curing the photocrosslinkable resin layer on and around the hole is used as an alignment mark even when the photocrosslinkable resin layer corresponding to the circuit pattern is cured, Since the photocrosslinkable resin layer on the through-hole is thin, tent breakage occurs, and the shape of the through-hole is difficult to be accurately recognized. As a result, misalignment occurs during the second curing of the circuit pattern. There was a case.

  Further, in order to avoid the tent tearing of the photocrosslinkable resin as described above, the photocrosslinkability on and around the through-hole used as the alignment mark when the photocrosslinkable resin layer on and around the hole is cured. By curing the resin layer, the tenting strength on the through hole that is the alignment mark is maintained. However, in general, the cured portion of the photocrosslinkable resin is designed to develop a color, and this color change changes the contrast of the edge of the through hole, making it difficult to accurately recognize the shape of the through hole. The problem of misalignment during pattern curing cannot be completely solved by this method.

International Publication No. 2009/096438 Pamphlet

  It is an object of the present invention to provide a method for producing a conductive pattern by a subtractive method. In handling after thinning, even if there is contact between substrates, contact with a conveyor or a suction pad in a transporting process, loading and receiving process. An object of the present invention is to provide a method for producing a conductive pattern which can prevent displacement even when the thinned surface has no scratches or dents and the photocrosslinkable resin layer is cured twice.

As a result of intensive studies to solve the above problems, the present inventors have
(1) In a method for producing a conductive pattern by a subtractive method, the conductive pattern includes at least a first conductive pattern portion and a second conductive pattern portion, and (a) a substrate on which a conductive layer is provided A step of forming a photocrosslinkable resin layer thereon, (b) a step of curing the photocrosslinkable resin layer corresponding to the first conductive pattern portion, and (c) thinning treatment of the photocrosslinkable resin layer with an alkaline aqueous solution. (D) a step of curing at least a portion of the photocrosslinkable resin layer corresponding to the second conductive pattern portion, (e) a development step, and (f) a method for producing a conductive pattern including an etching step in this order. A part of the cured portion of the photocrosslinkable resin layer formed in the step (b) is used as an alignment mark in the step (d) to cure the photocrosslinkable resin. A method for manufacturing the over emissions,
(2) In the method for producing a conductive pattern by a subtractive method, the conductive pattern is composed of at least a land portion, a first conductive pattern portion, and a second conductive pattern portion, and has (a ′) a hole, And a step of forming a photocrosslinkable resin layer on a substrate provided with a conductive layer inside the hole, and (b ′) a step of curing the photocrosslinkable resin layer corresponding to the land portion and the first conductive pattern portion. (C) a step of thinning the photocrosslinkable resin layer with an aqueous alkali solution, (d) a step of curing at least a portion of the photocrosslinkable resin layer corresponding to the second conductive pattern portion, (e) a developing step, (F) In the conductive pattern manufacturing method including the etching steps in this order, a part of the cured portion of the photocrosslinkable resin layer formed in the step (b ′) is used as an alignment mark in the step (d). The method for manufacturing a conductive pattern characterized in that curing the photo-crosslinkable resin,
I found.

  In the present invention, by forming at least the first conductive pattern portion and the second conductive pattern portion, in handling after the thinning process, the conveyor and suction in the contact, transfer process, loading and receiving processes between the substrates. Even if there is contact with the pad, it is possible to provide a method for producing a conductive pattern in which the thinned surface has no scratches or dents.

  That is, in the method (1) for producing a resist pattern of the present invention, after the photocrosslinkable resin layer corresponding to the first conductive pattern portion is cured, the uncured photocrosslinkable resin layer is thinned. Thereby, a 1st conductive pattern part turns into a thick cured film, and a level | step difference is formed with an uncured thinned part. Due to the formation of this step, for example, even when double-sided exposure is performed, substrates are placed on top of each other, conveyor conveyance or suction conveyance is performed, there is almost no direct contact with the thinned portion, and scratches and dents are generated. Can be prevented.

  In the method (2) for producing a resist pattern according to the present invention, after curing the photocrosslinkable resin layer corresponding to the land portion and the first conductive pattern portion, the uncured photocrosslinkable resin layer is thinned. I do. By curing the land portion in advance, a thick etching resist layer having tenting strength can be formed on and around the hole, and the tenting film is hardly broken in the etching process, and the conductive layer in the hole is etched. It becomes difficult to be done. Furthermore, the first conductive pattern part is also a thick cured film like the land part, and by forming a step with the uncured thinned part, it is possible to prevent scratches and dents due to direct contact with the thinned part. it can.

  In the present invention, the photocrosslinkable resin layer corresponding to the first conductive pattern portion is cured and the uncured portion is thinned, and then the photocrosslinkable resin layer corresponding to the second conductive pattern portion. In the step of curing the first conductive pattern and the second conductive pattern by using a part of the cured portion of the photocrosslinkable resin layer corresponding to the first conductive pattern as an alignment mark Can be provided.

  That is, in the conductive pattern manufacturing method (1) of the present invention, the photocrosslinkable resin layer corresponding to the first conductive pattern portion is cured in the step (b), and the uncured photocrosslinkable in the step (c). After thinning the functional resin layer, a part of the photocrosslinkable resin layer cured in the step (b) is used as an alignment mark in the step (d). Thereby, the position information of the alignment mark is accurately read in the step (d), and the positional deviation between the first conductive pattern and the second conductive pattern can be prevented.

  In the conductive pattern production method (2) of the present invention, the photocrosslinkable resin layer corresponding to the land portion and the first conductive pattern portion is cured in step (b ′), and uncured in step (c). After thinning the photocrosslinkable resin layer, a part of the photocrosslinkable resin layer cured in the step (b ′) is used as an alignment mark in the step (d). Thereby, the position information of the alignment mark in the step (d) is accurately read, and the positional deviation between the first conductive pattern and the second conductive pattern can be prevented.

It is sectional process drawing which shows an example of the production method (1) of the conductive pattern of this invention. It is sectional process drawing which shows an example of the production method (2) of the conductive pattern of this invention. It is a schematic sectional drawing which shows a 1st conductive pattern part and a 2nd conductive pattern part. It is a schematic sectional drawing which shows a 1st conductive pattern part and a 2nd conductive pattern part. It is a schematic overhead view which shows the through-hole used as an alignment mark formed in the Example and the comparative example, and the circular pattern part of the pattern data used in the Example and the comparative example.

  Hereinafter, the method for producing a conductive pattern of the present invention will be described in detail.

  FIG. 1 is a cross-sectional process diagram illustrating an example of a method (1) for producing a conductive pattern of the present invention. As the substrate 2, an insulating substrate 4 having a conductive layer 3 on the surface is used. In the step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 3 of the substrate 2. In the step (b), the photocrosslinkable resin layer 1 corresponding to the first conductive pattern portion is cured to form the first conductive pattern portion 5. In step (c), the photocrosslinkable resin layer 1 is thinned with an aqueous alkali solution to form the thinned portion 7. In the step (d), a part of the first conductive pattern portion is used as an alignment mark, and at least a portion of the photocrosslinkable resin layer 1 corresponding to the second conductive pattern portion is cured to form a thin film of the second conductive pattern portion 6. Form. In the step (e), the thinned portion 7 of the photocrosslinkable resin layer is removed by development. In the step (f), the conductive layer 3 not covered with the first conductive pattern portion 5 and the second conductive pattern portion 6 of the photocrosslinkable resin is etched to obtain a conductive pattern.

  FIG. 2 is a cross-sectional process diagram illustrating an example of a conductive pattern manufacturing method (2) according to the present invention. As the substrate 2, an insulating substrate 4 having a hole 9 and having a conductive layer 3 provided on the surface and inside the hole is used. In the step (a ′), the photocrosslinkable resin layer 1 is formed on the conductive layer 3 on the surface of the substrate 2 so as to close the hole 9. In the step (b ′), the photocrosslinkable resin layer 1 corresponding to the land portion and the first conductive pattern portion is cured to form the land portion 8 and the first conductive pattern portion 5. In step (c), the photocrosslinkable resin layer 1 is thinned with an aqueous alkali solution to form the thinned portion 7. In the step (d), a part of the first conductive pattern portion is used as an alignment mark, and at least a portion of the photocrosslinkable resin layer 1 corresponding to the second conductive pattern portion is cured to form a thin film of the second conductive pattern portion 6. Form. In the step (e), the thinned portion 7 of the photocrosslinkable resin layer is removed by development. In the step (f), the conductive layer 3 not covered with the first conductive pattern portion 5 and the second conductive pattern portion 6 of the photocrosslinkable resin is etched to obtain a conductive pattern.

<Steps (a) and (a ′)>
In the step (a), a photocrosslinkable resin layer is formed on at least one surface of a substrate having a conductive layer on the surface. In the step (a ′), a photocrosslinkable resin layer is formed on at least one surface of a substrate having a hole and a surface and a conductive layer provided inside the hole. For the formation of the photocrosslinkable resin layer, for example, a thermocompression laminator device that presses and presses a heated rubber roll can be used. The temperature is 40 ° C to 150 ° C, more preferably 60 ° C to 120 ° C. In the case of laminating with a hot roll, the pressure is linear pressure and is in the range of 1 N / cm to 100 N / cm, more preferably in the range of 5 N / cm to 50 N / cm. The substrate may be subjected to pretreatment such as alkali degreasing and pickling.

  Examples of the substrate having a conductive layer on the surface include a printed wiring board and a lead frame substrate. Examples of the printed wiring board include a flexible substrate and a rigid substrate. The thickness of the insulating substrate of the flexible substrate is 5 to 125 μm, and a metal foil layer of 1 to 35 μm is provided as a conductive layer on both sides or one side, and the flexibility is high. As the material for the insulating substrate, polyimide, polyamide, polyphenylene sulfide, polyethylene terephthalate, liquid crystal polymer, or the like is usually used. The material having the metal foil layer on the insulating substrate is an insulating substrate by an adhesive method of bonding with an adhesive, a casting method of applying a resin liquid which is an insulating substrate material on the metal foil, a sputtering method or a vapor deposition method. Produced by any method such as sputtering / plating method, which forms a metal foil layer by electrolytic plating on a thin conductive layer (seed layer) with a thickness of several nanometers formed on a resin film, or laminating method, which is attached by hot press. May be used. As the metal of the metal foil layer, any metal such as copper, aluminum, silver, nickel, chromium, or an alloy thereof can be used, but copper is generally used.

  As a rigid substrate, a paper substrate or glass substrate soaked with epoxy resin or phenol resin is laminated to form an insulating substrate, and a metal foil is placed on one or both sides as a conductive layer, and heated and pressed. A laminated layer provided with a metal foil layer can be used. Moreover, the multilayer board which has a through-hole and a non-through-hole, and the multilayer shield board produced by laminating | stacking a prepreg, metal foil, etc. after an inner layer wiring pattern process is also mentioned. The thickness is 60 μm to 3.2 mm, and the material and thickness thereof are selected according to the final use form as a printed circuit board. Examples of the material for the metal foil layer include copper, aluminum, silver, and gold. Copper is the most common. Examples of these printed circuit boards are “Printed Circuit Technology Handbook” (edited by Japan Printed Circuit Industry Association, published in 1987, published by Nikkan Kogyo Shimbun Co., Ltd.) and “Multilayer Printed Circuit Handbook” (JA Scarlet). Ed., Published in 1992, published by Modern Chemical Co., Ltd.). Examples of the lead frame substrate include iron nickel alloy and copper alloy substrates.

  For a substrate having a hole and a conductive layer provided on the surface and inside the hole, for example, a hole is formed by drilling or lasering on a substrate having a metal foil layer on the surface of the insulating substrate. It is produced by performing a plating process such as electrolytic plating or electrolytic plating to form a plated metal layer on the surface including the inside of the hole.

  The photocrosslinkable resin layer is a resin layer in which an exposed portion is crosslinked and insolubilized in a developer, and a negative dry film resist is generally used for circuit formation. A commercially available dry film resist has at least a photocrosslinkable resin layer, and is provided with a photocrosslinkable resin layer on a support layer film such as polyester. In some cases, a protective film such as polyethylene covers the photocrosslinkable resin layer. Many are sandwiched. In the present invention, commercially available dry film resists that can be used as the photocrosslinkable resin layer include, for example, Sunfort (registered trademark) series (manufactured by Asahi Kasei E-materials), Photec (registered trademark) series (manufactured by Hitachi Chemical Co., Ltd.). ), Liston (registered trademark) series (manufactured by DuPont MRC Dry Film), ALPHA (registered trademark) series (manufactured by Nichigo Morton), and the like.

  The thickness of the photocrosslinkable resin layer is preferably 15 to 100 μm, and more preferably 20 to 50 μm. If the thickness is less than 15 μm, resist peeling or disconnection may occur due to mixing of bubbles with dust as a nucleus or uneven followability, and if it exceeds 100 μm, the amount dissolved and removed by thinning increases. In some cases, the thinning time becomes longer and the productivity becomes worse. In addition, it may be difficult to maintain stable quality in continuous processing.

<Process (b) and process (b ')>
In the conductive pattern manufacturing method (1) of the present invention, in the step (b), the photocrosslinkable resin layer corresponding to the first conductive pattern portion is cured. In the handling of the substrate, when the substrates are stacked on top of each other, or when double-sided exposure is performed, the photocrosslinkable resin layer corresponding to the first conductive pattern portion serves as a support and becomes a thinned photocrosslinkable resin. It is possible to prevent the layers from coming into direct contact. Exposure methods include xenon lamps, high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, reflection image exposure using UV fluorescent lamps as light sources, single-sided or double-sided contact exposure systems using photo tools, proximity systems, projection systems, and laser scanning. Examples include an exposure method.

  In the conductive pattern production method (2) of the present invention, in the step (b ′), the photocrosslinkable resin layer of the land portion and the first conductive pattern portion is cured. The land portion is exposed by setting a desired land width so that tenting is possible. Thick film tents on the hole and its surroundings, and the first conductive pattern part of the thick film as well as the land part are formed to prevent scratches and dents due to direct contact with the thinned part. Can do.

  As the area of the first conductive pattern portion increases, the contact risk of the thin resin layer decreases. The area of the first conductive pattern portion is preferably 30% to 99%, more preferably 50% to 99% of the total area of the substrate. As a specific example of the first conductive pattern portion and the second conductive pattern portion, as shown in FIG. 3, a wide space portion is used as the first conductive pattern portion, and the second conductive pattern portion is used as a narrow space wiring portion. An example in which only the periphery is used or the entire pattern is the second conductive pattern portion, and a pattern in which the line width of the second conductive pattern portion is uniformly reduced as shown in FIG. 4 is used as the first conductive pattern portion. Examples are given. Moreover, the example which makes the pattern which reduced the line | wire width of the 2nd conductive pattern part other than a land part uniformly the 1st conductive pattern part is also mentioned.

  The alignment in the step (b) can be performed on the basis of a through hole used as an alignment mark in the step (a). The alignment in the step (b ′) can be performed on the basis of forming a through hole different from the hole in which the conductive layer is provided in the step (a ′). As a method of providing a through hole used as an alignment mark in a substrate, for example, a method of forming a hole by a drill or a laser on a substrate having a metal foil layer on the surface of an insulating substrate can be mentioned. The through hole used as the alignment mark may be either plated or unplated.

  In the steps (b) and (b ′), by using a through hole formed in the substrate as an alignment mark, it is possible to prevent the positional deviation between the front surface and the back surface in the first conductive pattern and the positional deviation between the layers of the multilayer substrate. it can. Then, by using a part of the cured portion of the photocrosslinkable resin layer corresponding to the first conductive pattern as the alignment mark when the portion of the photocrosslinkable resin layer corresponding to the second conductive pattern is cured, the first With both the conductive pattern and the second conductive pattern, it is possible to prevent positional deviation between the front surface and the rear surface and interlayer positional deviation of the multilayer substrate.

<Step (c)>
In the step (c), the uncured photocrosslinkable resin layer is thinned with an aqueous alkali solution to form a thinned portion. When the support layer film is provided on the photocrosslinkable resin layer, the thinning treatment is performed after the film is peeled off. The thinning treatment is a treatment for reducing the thickness of the photocrosslinkable resin layer substantially uniformly. Specifically, the thickness is reduced to 0.05 to 0.9 times the thickness before the thinning treatment. That means.

  Examples of the alkaline aqueous solution according to the present invention include alkali metal carbonates such as lithium, sodium or potassium carbonate or bicarbonate, alkali metal phosphates such as potassium and sodium phosphate, lithium, sodium or potassium water. Inorganic alkaline compounds selected from alkali metal hydroxides such as oxides, alkali metal silicates such as potassium and sodium silicates, alkali metal sulfites such as potassium and sodium sulfites, ethanolamines, ethylamines Organic alkaline compounds such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, trimethyl-2-hydroxyethylammonium hydroxide (choline), ethylenediamine, diethylenetriamine, triethylenetetramine Containing at least one kind of. Among these, it is preferable to include at least one of inorganic alkali compounds selected from alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, and alkali metal silicates. Furthermore, alkali metal carbonates are particularly preferred from the viewpoints of the ability to dissolve the photocrosslinkable resin layer, the buffering ability to maintain the pH of the treatment liquid, the maintainability of the apparatus, and the like.

  The content of the alkaline compound is preferably 5 to 20% by mass. If it is less than 5% by mass, the micelles are hardly insolubilized, so that the micelles solubilized in the middle of dissolution and removal are dissolved and diffused, and in-plane unevenness occurs in the thinning process. Moreover, when it exceeds 20 mass%, precipitation and isolation | separation of an alkaline compound will occur easily and it is inferior to the temporal stability of a liquid, and workability | operativity. The pH of the solution is preferably in the range of 9-12. In addition, a small amount of a surfactant, an antifoaming agent, a solvent and the like can be added as appropriate.

  The step (c), which is a thinning treatment of the photocrosslinkable resin layer, is preferably processed separately in at least two steps. First, by supplying an excessively high concentration aqueous alkali solution, the photocrosslinkable resin layer component that has been micellized in the middle of dissolution is once insolubilized to suppress dissolution and diffusion into the treatment liquid. Next, an aqueous solution or water having a pH of 5 to 10, more preferably a pH of 6 to 8, containing at least any one of inorganic alkali compounds selected from alkali metal carbonates, alkali metal phosphates, and alkali metal silicates is supplied. Then, the insolubilized photocrosslinkable resin layer component is redispersed and dissolved and removed. When the pH of the aqueous solution is less than 5, the photocrosslinkable resin component dissolved by redispersion aggregates and becomes insoluble sludge and adheres to the thinned photocrosslinkable resin layer surface. On the other hand, if the pH of the aqueous solution exceeds 10, dissolution and diffusion of the photocrosslinkable resin layer is promoted, and film thickness unevenness occurs in the surface, which is not preferable. The pH of the aqueous solution is appropriately adjusted using sulfuric acid, phosphoric acid, hydrochloric acid or the like. Further, it is preferable that the supply flow rate of the aqueous solution is large. If the supply flow rate is insufficient, the redispersibility of the insolubilized photocrosslinkable resin layer component is deteriorated, and poor dissolution tends to occur. As a result, precipitation of insoluble components is observed on the surface of the photocrosslinkable resin layer after thinning, and tackiness may become a problem.

  There are dipping method, paddle method, spray method, brushing, scraping and the like as the thinning treatment method, and the spray method is most suitable from the viewpoint of the dissolution rate of the photocrosslinkable resin layer. In the case of the spray method, the treatment conditions (temperature, time, spray pressure) are appropriately adjusted according to the dissolution rate of the photocrosslinkable resin layer to be used. Specifically, the treatment temperature is preferably 10 to 50 ° C, more preferably 15 to 40 ° C, and further preferably 15 to 35 ° C. The spray pressure is preferably 0.01 to 0.5 MPa, and more preferably 0.02 to 0.3 MPa.

<Step (d)>
In the step (d), a part of the photocrosslinkable resin layer corresponding to the first conductive pattern cured in the steps (b) and (b ′) is used as an alignment mark, and at least in the second conductive pattern portion. The corresponding part of the photocrosslinkable resin layer is cured. As the shape of the photocrosslinkable resin layer used as the alignment mark, a binarizable point-symmetric figure is suitable, and examples thereof include a perfect circle and a square.

  In the method for producing a conductive pattern of the present invention, a step is formed between the land portion and the first conductive pattern portion and the thinned photocrosslinkable resin layer, and therefore, the contact exposure method is used in the exposure of the second conductive pattern. In this case, the influence of the diffracted light is large, and the resolution may be lowered. Furthermore, since there are two exposure steps, the exposure method that requires a photo tool is disadvantageous in terms of cost. Therefore, if non-contact direct imaging exposure is performed, the resolution is not reduced by the diffracted light that occurs at the level difference between the land and the thin resin layer, and no photo tool is required. You can say that.

<Process (e)>
In the step (e), the uncured photocrosslinkable resin layer is removed with a developer to form an etching resist layer. As a development method, a developer suitable for the photocrosslinkable resin layer to be used is used, spray is sprayed from the vertical direction of the substrate toward the substrate surface, and unnecessary portions are removed as an etching resist pattern to form a circuit pattern. A corresponding etching resist layer is formed. In general, an aqueous sodium carbonate solution of 0.3 to 2% by mass is used.

<Step (f)>
In the step (f), a fine conductive pattern is produced by etching a conductive layer that is not protected by the etching resist layer. In the etching process, a method described in “Handbook of Printed Circuit Technology” (edited by Japan Printed Circuit Industry Association, published in 1987, published by Nikkan Kogyo Shimbun) can be used. The etching solution may be one that can dissolve and remove the metal foil layer, and at least the etching resist layer has resistance. In general, when copper is used for the conductive layer, a ferric chloride aqueous solution, a cupric chloride aqueous solution, or the like can be used. Following the etching, the conductive resist pattern can be prepared by removing the etching resist layer with a high pH aqueous solution containing an alkaline compound such as sodium hydroxide, an organic solvent, or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example.

Example 1
<Process (a)>
A glass substrate epoxy resin copper-clad laminate (area 406 mm × 510 mm, copper foil thickness 18 μm, substrate thickness 0.1 mm, trade name: CCL-E170, manufactured by Mitsubishi Gas Chemical Company) is used in FIG. As shown, four through holes A having a diameter of 3 mm were formed. On top of this, using a laminator for dry film equipped with a laminate roll having a heat-resistant silicone rubber lining surface treatment, while peeling off the protective film, the roll temperature was 100 ° C., the air pressure was 0.3 MPa, and the laminating speed was 1.00 m / min. Then, a dry film resist (trade name: Sunfort (registered trademark) AQ4059, thickness 40 μm, manufactured by Asahi Kasei E-Materials Co., Ltd.) was laminated.

<Step (b)>
A circuit pattern portion and a non-circuit pattern portion in which patterns of line / space = 120/30 μm, 110/40 μm, 100/50 μm, and 90/60 μm are mixed using the through hole A having a diameter of 3 mm formed in the step (a) as an alignment mark Using pattern data (for example, the guide portion, the solid portion, the circular pattern portions B and C shown in FIG. 5, etc.) (the area ratio of the non-circuit pattern portion is 10% of the total area of the substrate) The photocrosslinkable resin layer corresponding to the first conductive pattern portion was exposed under the trade name: LI-8500 (manufactured by Dainippon Screen Mfg. Co., Ltd.). The first conductive pattern portion was a non-circuit pattern portion and a circuit pattern portion of line / space = 110/40 μm, 100/50 μm, 90/60 μm. The ratio of the first conductive pattern portion to the total area of the substrate was 80%. In addition, the diameter of the circular pattern part B is 1.5 mm, and the diameter of the circular pattern part C is 50 μm, each of which is four pieces. In addition, the tent tearing of the photocrosslinkable resin layer on the through hole used as the alignment mark at the time of exposure did not occur.

<Step (c)>
After the support film of the dry film resist was peeled off, a thinning treatment was performed using a 10% by mass sodium carbonate aqueous solution so that the photocrosslinkable resin layer had an average thickness of 15 μm (liquid temperature 25 ° C., spray pressure 0.05 MPa), sufficient water washing, and cold air drying, to obtain a thinned photocrosslinkable resin layer.

<Step (d)>
Using the entire pattern data as the second conductive pattern portion, double-sided exposure of the photocrosslinkable resin layer after thinning was performed in a direct drawing apparatus (trade name: LI-8500, manufactured by Dainippon Screen Mfg. Co., Ltd.). Exposure was performed using a total of four circular pattern portions B having a diameter of 1.5 mm cured in step (b) as alignment marks.

<Process (e)>
Development processing was performed using a 1% by mass aqueous sodium carbonate solution (solution temperature 30 ° C., spray pressure 0.15 MPa) to form an etching resist layer. When the obtained etching resist layer was observed with an optical microscope, no defects such as line thinning, disconnection, line thickening, and short-circuiting were observed in any of the thick film part and the thinned part. Further, when observed with a laser microscope (trade name: VK-8510, manufactured by Keyence Corporation), the distance between the centers of the first conductive pattern portion and the second conductive pattern portion was measured for a total of four circular pattern portions C having a diameter of 50 μm. The average was 8 μm.

<Step (f)>
Etching was performed by treating the substrate on which the etching resist layer was formed with a ferric chloride solution (liquid temperature: 45 ° C., spray pressure: 0.20 MPa) and removing the copper foil that was not protected by the etching resist layer. Subsequently, the remaining etching resist layer was removed with a 3% by mass sodium hydroxide solution at a liquid temperature of 40 ° C. to obtain a conductive pattern. When the obtained conductive pattern was observed with an optical microscope, no disconnection or short defect, which was a practical problem, was found.

Examples 2-4
About the exposure area | region of the 1st conductive pattern part, except having changed as follows, preparation of the conductive pattern was performed by the same method as Example 1. FIG. The ratio of each first conductive pattern portion to the total area of the substrate is 60%, 35%, and 10%. For the four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in the step (e), the average distance between the centers of the first conductive pattern portion and the second conductive pattern portion is 7 μm, 8 μm, and 8 μm, respectively. there were. In addition, in the conductive pattern obtained in the step (f), no disconnection or short-circuit defect that was a practical problem was found.

(First conductive pattern part)
Example 2: Non-circuit pattern part and line / space = 100/50 μm, 90/60 μm circuit pattern part Example 3: Non-circuit pattern part and line / space = 90/60 μm circuit pattern part Example 4: Non-circuit Pattern part

Example 5
<Step (a ′)>
Glass substrate epoxy resin copper clad laminate (area 406 mm x 510 mm, copper foil thickness 18 μm, substrate thickness 0.1 mm, trade name: CCL-E170, manufactured by Mitsubishi Gas Chemical Company) 5 mm in diameter using a drill As shown in FIG. 5, after forming 4 through-holes A with a diameter of 3 mm, a copper-clad laminate with holes in which a plated copper layer with a thickness of 15 μm is formed on the inside of the through-hole with a diameter of 5 mm and on the copper foil A plate was made. Using a laminator for dry film provided with a laminate roll having a heat-resistant silicon rubber lining surface-treated on the perforated copper-clad laminate, the roll temperature is 100 ° C., the air pressure is 0.3 MPa, and the laminating speed is 1 while peeling off the protective film. A dry film resist (trade name: Sunfort (registered trademark) AQ4059, thickness 40 μm, manufactured by Asahi Kasei E-Materials) was laminated at 0.000 m / min.

<Process (b ')>
Using the through hole A having a diameter of 3 mm formed in the step (a ′) as an alignment mark, a land pattern (the area ratio of the land pattern is 10% of the total area of the substrate) and line / space = 120/30 μm, 110/40 μm, 100 / Pattern data (non-circuit pattern) having a circuit pattern portion in which 50 μm and 90/60 μm patterns are mixed, and a non-circuit pattern portion (for example, a guide portion, a solid portion, and the circular pattern portions B and C shown in FIG. 5) The area ratio of the portion is 10% of the total area of the substrate), and the portion of the photocrosslinkable resin layer corresponding to the first conductive pattern portion of the direct drawing apparatus (trade name: LI-8500, manufactured by Dainippon Screen Mfg. Co., Ltd.) is used. Exposure was performed. The first conductive pattern portion was a non-circuit pattern portion, land pattern and line / space = 110/40 μm, 100/50 μm, 90/60 μm circuit pattern portion. The ratio of the first conductive pattern portion to the total area of the substrate was 80%. In addition, the diameter of the circular pattern part B is 1.5 mm, and the diameter of the circular pattern part C is 50 μm, each of which is four pieces. In addition, the tent tearing of the photocrosslinkable resin layer on the through hole used as the alignment mark did not occur.

<Step (c)>
After peeling off the support layer film, thinning treatment was performed using a 10% by mass aqueous sodium carbonate solution so that the average thickness of the photocrosslinkable resin layer was 15 μm (liquid temperature 25 ° C., spray pressure 0.05 MPa). After sufficient washing with water and drying with cold air, a thinned photocrosslinkable resin layer was obtained.

<Step (d)>
Using the entire pattern data as the second conductive pattern portion, double-sided exposure of the photocrosslinkable resin layer after thinning was performed in a direct drawing apparatus (trade name: LI-8500, manufactured by Dainippon Screen Mfg. Co., Ltd.). At this time, exposure was performed using four circular pattern portions B having a diameter of 1.5 mm cured in step (b) as alignment marks.

<Process (e)>
Development processing was performed using a 1% by mass aqueous sodium carbonate solution (solution temperature 30 ° C., spray pressure 0.15 MPa) to form an etching resist layer. When the obtained etching resist layer was observed with an optical microscope, no defects such as line thinning, disconnection, line thickening, and short-circuiting were observed in any of the thick film part and the thinned part. Further, when observed with a laser microscope (trade name: VK-8510, manufactured by Keyence Corporation), the distance between the centers of the first conductive pattern portion and the second conductive pattern portion was measured for a total of four circular pattern portions C having a diameter of 50 μm. The average was 7 μm.

<Step (f)>
The substrate on which the etching resist layer was formed was treated with a ferric chloride solution (liquid temperature: 45 ° C., spray pressure: 0.20 MPa), and etching was performed by removing the copper foil other than the etching resist layer. Subsequently, the remaining etching resist layer was removed with a 3% by mass sodium hydroxide solution at a liquid temperature of 40 ° C. to obtain a conductive pattern. When the obtained conductive pattern was observed with an optical microscope, no disconnection or short defect, which was a practical problem, was found.

Examples 6-8
About the exposure area | region of the 1st conductive pattern part, except having changed as follows, preparation of the conductive pattern was performed by the same method as Example 5. FIG. The ratio of each first conductive pattern portion to the total area of the substrate is 60%, 40%, and 20%. For the four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in step (e), the average distance between the centers of the first conductive pattern portion and the second conductive pattern portion is 8 μm, 7 μm, and 7 μm, respectively. Met. In addition, the conductive pattern obtained in the step (f) had no practical disconnection or short-circuit defect, and no disconnection of the inner wall of the hole was observed.

(First conductive pattern part)
Example 6: Circuit pattern part of non-circuit pattern part, land pattern and line / space = 100/50 μm, 90/60 μm Example 7: Circuit pattern part of non-circuit pattern part, land pattern and line / space = 90/60 μm Example 8: Non-circuit pattern portion, land pattern

Comparative Example 1
A conductive pattern was produced in the same manner as in Example 1 except that the entire photo-resin layer was thinned without curing the photocrosslinkable resin layer corresponding to the first conductive pattern portion. After the thinning treatment, the uncured thinned resin layer was exposed on the entire surface, and pattern disconnection or short defects due to scratches or dents occurred frequently during handling during double-sided exposure and when placing the substrates on top of each other. .

Comparative Example 2
A conductive pattern was produced in the same manner as in Example 5 except that the exposure area of the first conductive pattern portion was only the land pattern. In the obtained conductive pattern, no disconnection of the inner wall of the hole was observed, but there was no pattern disconnection or short-circuit defect derived from scratches or dents that were thought to have occurred during handling during double-sided exposure or when stacking substrates. It was sporadic.

Comparative Example 3
A conductive pattern was prepared in the same manner as in Example 5 except that the exposure area of the first conductive pattern portion was only a land pattern, and a polyethylene terephthalate film having a thickness of 16 μm was re-laminated after the thinning process. The polyethylene terephthalate film did not follow the step between the land pattern, which is the first conductive pattern portion, and the thinned portion, and line thickening due to diffracted light and a short defect occurred around the step. In addition, film loss due to polymerization inhibition occurred due to the presence of air (oxygen) around the step.

Comparative Example 4
A conductive pattern was produced in the same manner as in Example 1 except that the through hole A4 formed in the step (a) was used as the alignment mark in the step (d). At this time, when the photocrosslinkable resin layer was thinned in the step (c), the tent was broken on the through hole. For a total of four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in the step (e), the average distance between the centers of the first conductive pattern portion and the second conductive pattern portion was 25 μm. In the conductive pattern obtained in the step (f), short-circuit defects derived from misalignment between the first conductive pattern portion and the second conductive pattern portion frequently occurred.

Comparative Example 5
In the step (b), the photocrosslinkable resin layer on and around the through hole A used as the alignment mark (within 300 μm range from the outer edge of the through hole) is also cured, and then in the step (d), the through hole (A) A conductive pattern was produced in the same manner as in Example 1 except that was used as an alignment mark. The average distance between the centers of the first conductive pattern portion and the second conductive pattern portion was 20 μm for a total of four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in the step (e). In the conductive pattern obtained in the step (f), short-circuit defects derived from misalignment between the first conductive pattern portion and the second conductive pattern portion frequently occurred.

Comparative Example 6
A conductive pattern was produced in the same manner as in Example 5 except that in the step (d), the through hole A4 having a diameter of 3 mm formed in the step (a ′) was used as the alignment mark. In the step (c), when the photocrosslinking resin layer was thinned, the tenting film on the through hole having a diameter of 3 mm was broken. For a total of four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in the step (e), the average distance between the centers of the first conductive pattern portion and the second conductive pattern portion was 28 μm. In the conductive pattern obtained in the step (f), short-circuit defects derived from misalignment between the first conductive pattern portion and the second conductive pattern portion frequently occurred.

Comparative Example 7
In the step (b ′), the photocrosslinkable resin layer on and around the through hole A used as the alignment mark (within 300 μm from the outer edge of the through hole) is also cured, and then in the step (d), the through hole A A conductive pattern was produced in the same manner as in Example 5 except that was used as an alignment mark. The average distance between the centers of the first conductive pattern portion and the second conductive pattern portion was 20 μm for a total of four circular pattern portions C having a diameter of 50 μm of the etching resist layer obtained in the step (e). In the conductive pattern obtained in the step (f), short-circuit defects derived from misalignment between the first conductive pattern portion and the second conductive pattern portion frequently occurred.

  The present invention is widely used for producing a fine conductive pattern using a subtractive method, and can be used for a method of manufacturing a lead frame in addition to the printed wiring board described in the embodiments.

1 Photocrosslinkable resin layer (uncured part)
2 Substrate 3 Conductive layer 4 Insulating substrate 5 First conductive pattern part (thick film curing part)
6 Second conductive pattern part (thin film hardening part)
7 Thinning part 8 Land part (thick film hardening part)
9 Hole A Through hole with a diameter of 3 mm B Circular pattern with a diameter of 1.5 mm C Circular pattern with a diameter of 50 μm

Claims (2)

  In a method for producing a conductive pattern by a subtractive method, the conductive pattern is composed of at least a first conductive pattern portion and a second conductive pattern portion, and (a) on a substrate on which a conductive layer is provided on the surface A step of forming a photocrosslinkable resin layer, (b) a step of curing the photocrosslinkable resin layer corresponding to the first conductive pattern portion, and (c) performing a thinning process of the photocrosslinkable resin layer with an alkaline aqueous solution. Formed in step (b), including a step, (d) a step of curing at least a portion of the photocrosslinkable resin layer corresponding to the second conductive pattern portion, (e) a development step, and (f) an etching step in this order. A method for producing a conductive pattern, wherein the photocrosslinkable resin is cured by using a part of the cured portion of the photocrosslinkable resin layer as an alignment mark in the step (d).   In the method for producing a conductive pattern by a subtractive method, the conductive pattern is composed of at least a land portion, a first conductive pattern portion, and a second conductive pattern portion, and has (a ′) a hole, and a surface and a hole. A step of forming a photocrosslinkable resin layer on a substrate having a conductive layer therein; (b ′) a step of curing the photocrosslinkable resin layer corresponding to the land portion and the first conductive pattern portion; c) a step of thinning the photocrosslinkable resin layer with an aqueous alkali solution, (d) a step of curing the photocrosslinkable resin layer corresponding to at least the second conductive pattern portion, (e) a developing step, (f) ) Including etching steps in this order, and using the part of the cured portion of the photocrosslinkable resin layer formed in step (b ′) as an alignment mark in step (d), curing the photocrosslinkable resin. The method for manufacturing a conductive pattern to.

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