JP5444063B2 - Resin layer thinning treatment liquid management method - Google Patents

Description

  The present invention relates to a method for managing a resin layer thinning treatment liquid.

  As a method for manufacturing printed wiring boards and lead frames, an etching substrate 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 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 the devices have been increased in density and conductive patterns. Has a conductive pattern of 50 to less than 80 μm and a conductor gap of 50 to 80 μm. 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) a step of forming a photocrosslinkable resin layer on a substrate having a conductive layer on the surface, (b) an alkali metal carbonate, an alkali metal phosphate, an alkali metal A step of thinning the photocrosslinkable resin layer with a resin layer thinning treatment solution comprising an aqueous solution containing 5 to 20% by mass of at least one inorganic alkaline compound selected from hydroxide and alkali metal silicate; There has been proposed a method for producing a conductive pattern including a c) circuit pattern exposure step, (d) a development step, and (e) an etching step in this order (for example, see Patent Document 1). According to this method, since a thick photocrosslinkable resin layer is formed on the substrate, problems such as bubble mixing and a decrease in followability of irregularities are unlikely to occur, and the photocrosslinkable resin layer after thinning treatment Is used to form the etching resist layer, so that a fine conductive pattern can be formed.

  However, the method of Patent Document 1 has the following problems because a high-concentration alkaline aqueous solution is used for thinning the photocrosslinkable resin layer in the step (b). First, when the resin layer thinning treatment liquid comes into contact with air, it deteriorates by producing carbonate. Further, the reduction of the processing liquid due to the substrate taking out the processing liquid due to the thinning process is also a factor that destabilizes the thinning capability (for example, see Patent Document 2). Furthermore, concentration due to water evaporation cannot be ignored.

  In order to keep the performance of the resin layer thinning treatment liquid constant, it is essential to manage the resin layer thinning treatment liquid based on some index that reflects the thinning ability.

  In the liquid crystal substrate manufacturing process, the printed wiring board process, and the like, there is a pH of the developer itself as an index reflecting the developing ability in the management of the alkaline developer used for developing the photosensitive organic resin. In the case of a resin layer thinning treatment, an alkali-soluble resin having a carboxylic acid end contained in the photocrosslinkable resin layer and a high concentration aqueous alkali solution contact and react with each other, so that the pH is higher than the value measured at the actual concentration. Since it is observed low, it is difficult to control at the pH of the treatment liquid.

  A management method of an alkaline developer by neutralization titration has also been proposed, but when this management method is applied to the step (b) of Patent Document 1, various problems may occur (for example, see Patent Document 3). ).

  That is, in the case of the developer management method in Patent Document 3, water is replenished when the alkali concentration of the solution obtained by automatically sampling the developer is higher than the target, and when it is low, replenishment with a higher concentration than the developer is performed. Replenish the solution according to the deviation from the target concentration. The resin layer thinning treatment liquid in Patent Document 1 requires more strict management because the concentration change has a larger influence on the treatment than the alkaline developer used in the liquid crystal substrate manufacturing process, the printed wiring board process, and the like. Yes, if a high concentration replenisher is additionally replenished, the thinning process becomes unstable.

  More specifically, in the case of the development process of the photosensitive resin layer with an alkaline developer, in anticipation that the concentration of the alkaline developer changes so that the photosensitive resin layer not photocrosslinked can be developed, The treatment is performed for 1.5 to 2.0 times the time (break point) at which the entire photosensitive resin layer is eluted. The photocrosslinked portion does not peel off at this time. On the other hand, in the step (b) in Patent Document 1, a photocrosslinkable resin layer that has not been photocrosslinked has to be uniformly thinned, and a slight amount generated by additionally replenishing a high concentration replenisher. Density deviation greatly affects the thinning amount. When replenishing a high-concentration replenisher, it may be possible to perform mechanical operations to instantaneously reach the target concentration by stirring the tank all at once. Since the treatment liquid is foamed and the foam may make the thinning process non-uniform, this is also not applicable.

  Depending on the number of treatments and the treatment area, a management method that replenishes quantitatively is considered effective, but in order not to cause even a slight deviation in concentration, a large amount of treatment solution must be supplied, and the resin layer is made thin. This is not preferable because the processing liquid is wasted.

International Publication No. 2009/096438 Pamphlet JP 2006-133560 A JP-A-9-236931

  The subject of this invention is (a) The process of forming a photocrosslinkable resin layer on the board | substrate with which the conductive layer is provided in the surface, (b) Alkali metal carbonate, alkali metal phosphate, alkali metal hydroxide A step of thinning the photocrosslinkable resin layer with a resin layer thinning treatment solution comprising an aqueous solution containing 5 to 20% by mass of at least one inorganic alkaline compound selected from alkali metal silicates, (c) circuit In the management method of the resin layer thinning treatment liquid in the conductive pattern production method including the pattern exposure step, (d) development step, and (e) etching step in this order, the resin layer thinning treatment containing a high concentration inorganic alkaline compound An object of the present invention is to provide a management method that makes it possible to keep the liquid thinning ability constant.

  (A) a step of forming a photocrosslinkable resin layer on a substrate having a conductive layer on the surface, (b) an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide, an alkali metal silicate A step of thinning the photocrosslinkable resin layer with a resin layer thinning treatment solution comprising an aqueous solution containing 5 to 20% by mass of at least one inorganic alkaline compound selected from: (c) a circuit pattern exposure step; d) In the management method of the resin layer thinning treatment liquid in the method for producing a conductive pattern including the developing step and (e) the etching step in this order, the concentration of the inorganic alkaline compound in the resin layer thinning treatment solution is obtained by a neutralization titration method. A method of managing a resin layer thinning treatment liquid characterized in that the concentration of the inorganic alkaline compound is maintained within a predetermined range by replenishing a liquid having the same concentration as the initial concentration. Akira issue has been solved.

  According to the present invention, by performing liquid management using the neutralization titration method, it is possible to perform strict management as compared with the liquid management method based on pH management, so that the resin layer thinning treatment liquid can be consumed wastefully. In addition, the environmental load can be reduced. In addition, by replenishing the liquid with the same concentration as the initial concentration, it is possible to perform stricter management compared to the case of replenishing the replenisher with a high concentration, and the resin layer thin film containing a high concentration inorganic alkaline compound can be used. The thinning ability of the treatment liquid can be kept constant.

It is a cross-sectional process drawing which shows an example of the production method of the conductive pattern including the process of thinning a photocrosslinkable resin layer.

  Hereinafter, the management method of the resin layer thinning treatment liquid of the present invention will be described in detail.

  FIG. 1 is a cross-sectional process diagram illustrating an example of a method for producing a conductive pattern including a process of thinning a photocrosslinkable resin layer. The substrate 2 is formed by providing a conductive layer 4 on one surface of an insulating substrate 5. In the step (a), the photocrosslinkable resin layer 1 is formed on the conductive layer 4 of the substrate 2. Step (b) includes steps (b1) to (b3). In the step (b1), an alkaline aqueous solution is infiltrated into the upper layer portion of the photocrosslinkable resin layer 1 to form a micellar photocrosslinkable resin layer 6. In the step (b2), the micellar photocrosslinkable resin layer 6 is dissolved and removed, and the photocrosslinkable resin layer 1 is thinned. In the step (b3), the photocrosslinkable resin layer 1 after thinning is washed with water, and then water droplets are removed. The step (b2) is not essential, and the step (b3) may be performed after the step (b1) to dissolve and remove the photocrosslinkable resin layer 6 that has been micellized by washing with water. In the step (c), a portion of the photocrosslinkable resin layer 1 corresponding to the circuit pattern is exposed to form a crosslinked portion 3. In the step (d), the photocrosslinkable resin layer (uncrosslinked portion) 1 is removed by development. In the step (e), the conductive layer 4 not covered with the cross-linked portion 3 of the photo-crosslinkable resin is etched to obtain a conductive pattern.

  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 heating temperature is preferably 100 ° C. or higher. 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 a 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.

  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 a photocrosslinkable resin layer include, for example, the Sunfort series (trade name, manufactured by Asahi Kasei E-Materials), the Fotec series (trade name, manufactured by Hitachi Chemical Co., Ltd.). , Liston series (trade name, manufactured by DuPont MRC Dry Film), ALPHA series (trade name, 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 the mixing of bubbles with dust as a core and the uneven followability. On the other hand, when the thickness exceeds 100 μm, not only the production cost of the photocrosslinkable resin layer is increased, but also the edge fusion of the produced photocrosslinkable resin layer is remarkable and the storage stability may be deteriorated.

  The thinning treatment of the photocrosslinkable resin layer in the present invention comprises three steps (b1) to (b3). First, in the step (b1), at least one inorganic alkaline compound selected from alkali metal carbonates, alkali metal phosphates, alkali metal hydroxides, and alkali metal silicates is 5 to 20% by mass, more preferably By supplying a resin layer thinning treatment liquid comprising an aqueous solution containing 10 to 15% by mass, the photocrosslinkable resin layer components that have been micellized in the middle of dissolution are once insolubilized, and dissolution and diffusion into the treatment liquid is suppressed. . If it is less than 5% by mass, the micelles are hardly insolubilized, so that the micelles solubilized in the course of dissolution and removal are dissolved and diffused, and in-plane unevenness occurs in the thinning process. Moreover, when it exceeds 20 mass%, precipitation of an inorganic alkaline compound will occur easily and it is inferior to the temporal stability of a liquid, and workability | operativity. In addition, a small amount of a surfactant, an antifoaming agent, a solvent and the like can be added as appropriate.

  In the step (b1), the resin layer thinning treatment liquid is repeatedly used. However, concentration by evaporation of water, removal of the treatment liquid at the time of substrate transfer, contact with carbon dioxide in the air, formation of carbonate by reaction, etc. It is difficult to keep the liquid thinning ability constant. However, if the state of the resin layer thinning treatment liquid is not controlled at a constant level, the thinning ability is destabilized, resulting in a difference in the film thickness after treatment, leading to a decrease in stable productivity and a decrease in yield.

  Therefore, in the present invention, the state of the resin layer thinning solution is made constant by a method of keeping the alkali concentration obtained by the neutralization titration method within a predetermined range.

  Specifically, a predetermined amount of the resin layer thinning solution is collected from a continuously operating thinning device, and while measuring pH, hydrochloric acid or sulfuric acid is added dropwise until the neutralization point is reached. The concentration of the inorganic alkaline compound is determined from the amount of the added acid. The concentration of the inorganic alkaline compound is calculated from the obtained titration curve. However, in the acidic region, the titration curve shifts due to the influence of the binder having a carboxylic acid group, and thus the exact concentration may not be estimated. Therefore, it is necessary to calculate the concentration in the alkaline region. When this concentration has shifted out of the predetermined range of the resin layer thinning treatment liquid, in the present invention, a liquid having the same concentration as the initial concentration of the resin layer thinning treatment liquid is added. The “predetermined range” refers to a concentration range of −5% to + 5% with respect to the initial concentration of the resin layer thinning treatment liquid, and is hereinafter also referred to as “target concentration”. By performing the operation of measuring the concentration of the inorganic alkaline compound by neutralization titration and adding the resin layer thinning treatment liquid every predetermined time, the thinning ability of the resin layer thinning treatment liquid is maintained within a certain range. It becomes possible.

  The process from neutralization titration to the addition of the resin layer thinning solution can also be performed automatically. As an automatic system, for example, at least automatically a function of sampling a thinning solution at predetermined intervals (metering pump, metering tube, etc.), a pH meter, a function of stirring the liquid (magnetic stirrer, etc.), A function to drop titrant (acid) (pulse motor driven pump, etc.), a function to set an estimated neutralization point pH, stop dropping the titrant, and a function to calculate the amount of titrant dropped , The function of calculating the concentration of the inorganic alkaline compound from the dripping amount, the function of setting the target concentration, and the initial amount calculated by [(target concentration−measured concentration) × resin layer thinning treatment liquid tank volume / target concentration] Examples thereof include a system including a function of supplying a liquid having the same concentration as the concentration (such as a metering pump) and a function of washing the titration container after completion of a series of titration measurements. The calculation formula for replenishing the liquid is based on the above, but it is preferable to make various corrections while observing the actual process.

  In the above example, the estimated neutralization point pH was set, and the concentration of the inorganic alkaline compound was calculated from the amount of acid dropped until that pH was reached. To increase the measurement accuracy, the titration end pH was neutralized. Set the pH past the point pH (about 7 to 6 if the neutralization point is pH 8), determine the amount of acid dripping that gives the largest rate of pH change from the start of acid dripping to the end of dripping, It is preferable to calculate the concentration of the inorganic alkaline compound from the amount of acid dropped so far as the neutralization point.

  Next, in the step (b2), the pH is 5 to 10, and more preferably the pH is 6 to 8 including at least one of inorganic alkali compounds selected from alkali metal carbonates, alkali metal phosphates, and alkali metal silicates. Then, the photocrosslinkable resin layer component insolubilized in the step (b1) is redispersed and dissolved and removed. In this way, by separating the step (b1) and the step (b2), the photocrosslinkable resin layer hardly dissolves in the treatment liquid in the step (b1), so that the change in solubility of the treatment liquid is small and stable continuous. There is an advantage that thinning processing can be performed. Further, in step (b2), carbonate, phosphate, and silicate all have an excellent buffer capacity in the alkaline region, and therefore when a part of the high-concentration alkaline aqueous solution is mixed from step (b1). However, it is possible to prevent an abrupt increase in pH, and it is possible to suppress a change in pH caused by uneven stirring and spray unevenness of the local treatment liquid and dissolution unevenness of the photocrosslinkable resin layer to the minimum. Furthermore, by using an aqueous solution having a pH of 5 to 10, the redispersibility of the photocrosslinkable resin layer component in (b2) can be kept constant, and a stable continuous thinning process can be performed.

In the step (b2), when the pH of the aqueous solution is less than 5, the photocrosslinkable resin component dissolved by redispersion may aggregate and become insoluble sludge and adhere to the thinned photocrosslinkable resin layer surface. On the other hand, when the pH of the aqueous solution exceeds 10, the dissolution and diffusion of the photocrosslinkable resin layer is promoted, and the film thickness unevenness may occur in the surface. The treatment liquid in step (b2) may be used after adjusting the pH of the liquid using sulfuric acid, phosphoric acid, hydrochloric acid, or the like. In the step (b2), it is preferable that the supply flow rate of the aqueous solution is large, and it is preferably 0.030 to 1.0 L / min per 1 cm ^{2 of the} photocrosslinkable resin layer. In the step (b2), when the supply flow rate is insufficient, the re-dispersibility of the insolubilized photocrosslinkable resin layer component is deteriorated, so that poor dissolution is likely 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.

  Subsequent to the step (b2), the surface of the photocrosslinkable resin layer after the treatment in the step (b3) is washed with water, and then water droplets are removed, thereby completing the thinning process of the photocrosslinkable resin layer. Examples of the washing water include industrial water, tap water, ion exchange water, and distilled water. Examples of the method for removing water droplets on the surface of the resin layer include an air knife, a liquid-absorbing roll, and hot air drying. An air knife is particularly preferable because there is no physical contact and good removal efficiency.

  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.

  There are a dipping method, a battle method, a spray method, brushing, scraping and the like as a thinning 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.

  In step (c), the circuit pattern is exposed. Circuit pattern exposure methods include xenon lamps, high-pressure mercury lamps, low-pressure mercury lamps, ultra-high-pressure mercury lamps, reflected image exposure using UV fluorescent lamps as light sources, single-sided or double-sided contact exposure systems using photo tools, proximity systems, and projection systems. In particular, single-sided and double-sided exposure using a photo tool is preferably used with a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, or a UV fluorescent lamp as a light source.

  In the step (d), the photocrosslinkable resin layer that has not been photocrosslinked is removed with a developing solution 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.

  In the step (e), a fine conductive pattern is formed by etching the exposed conductive layer other than 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.

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

Example 1
<Process (a)>
A heat-resistant silicone rubber lining was surface-treated on a glass substrate epoxy resin copper clad laminate (area 170 mm × 255 mm, copper foil thickness 12 μm, substrate thickness 0.4 mm, trade name: FR-4, manufactured by Mitsubishi Gas Chemical Company). Dry film resist (trade name: Sunfort AQ5038) at a roll temperature of 100 ° C., an air pressure of 0.30 MPa, and a laminating speed of 0.50 m / min while peeling off the protective film using a laminator for dry film equipped with a laminate roll. And a thickness of 50 μm, manufactured by Asahi Kasei E-Materials Co., Ltd.).

<Step (b1)>
The dry film resist was thinned using a horizontal conveyance type continuous processing apparatus. The treatment was performed under conditions of a liquid temperature of 25 ° C. and a spray pressure of 0.05 MPa. After peeling off the support layer film, the photocrosslinked resin layer component of the dry film resist was once insolubilized with a resin layer thinning solution containing 10% by mass of sodium carbonate as an inorganic alkaline compound. The tank capacity was 150 kg. At this time, a liquid management system based on neutralization titration was used to replenish a liquid having the same concentration as the initial concentration to keep the alkali concentration constant. For every 10 sheets processed, 50 ml of the processing solution was collected using a metering pump and a metering tube, diluted twice and neutralized, and the concentration of the inorganic alkaline compound was calculated. When the measured concentration was less than 9.5% by mass or more than 10.5% by mass, the liquid having the same concentration as the initial concentration was replenished until the concentration in the tank became 9.5 to 10.5% by mass. The replenishment volume averaged 100 ml .

<Steps (b2) to (b3)>
In step (b2), a resin layer thinning treatment solution containing 0.1% by mass of sodium carbonate (liquid temperature: 25 ° C., spray pressure: 0.05 MPa) is used as the resin layer thinning treatment solution, and the photocrosslinking is insolubilized. The resin component is re-dispersed and dissolved and removed. In step (b3), the surface of the photocrosslinkable resin layer after treatment is washed with water (liquid temperature: 25 ° C., spray pressure: 0.05 MPa), and then thinned with an air knife. Water droplets on the surface of the resin layer were removed. After the thinning treatment, the film thickness of the photocrosslinkable resin layer was measured at 10 points. Under the above conditions, when the thinning treatment of 50 sheets per day was continued for 100 days, the film thickness after the thinning of the photocrosslinkable resin layer was within the range of −1 μm to +1 μm from the average value. Liquid management was performed stably.

<Step (c)>
Using a photo tool in which a pattern of line / space = 25/25 μm is drawn, contact exposure is performed with a vacuum contact exposure apparatus equipped with a 3 kw ultrahigh pressure mercury lamp (trade name: URM-300, manufactured by Ushio Lighting Co., Ltd.) as a light source. went.

<Step (d)>
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. As a result of observing the obtained etching resist layer with an optical microscope, in the pattern of line / space = 25/25 μm, defects such as line thinning, disconnection, line thickening, and short-circuit were not observed.

<Process (e)>
Etching was performed by treating the substrate on which the etching resist layer was formed with a ferric chloride solution (liquid temperature 40 ° C., spray pressure 0.20 MPa) and 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 40 ° C. to obtain a conductive pattern. In the obtained conductive pattern, no disconnection or short defect, which was a practical problem, was observed.

(Comparative Example 1)
A conductive pattern was obtained under the same conditions as in Example 1 except that the neutralization titration was not used for the management of the resin layer thinning treatment liquid, and the liquid management was performed using pH. If the pH in the tank is managed so as not to deviate from the initial value, every time one sheet is processed, the liquid with the same concentration as the initial concentration must be replenished with an average of 1000 ml. Consumed wastefully.

(Comparative Example 2)
The same conditions as in Example 1 except that the neutralization titration is not used for the management of the resin layer thinning treatment liquid, the liquid is controlled by pH, and a high-concentration replenisher (11 mass% sodium carbonate aqueous solution) is used. Thus, a conductive pattern was obtained. Every time one sheet was processed, an average of 200 ml of high-concentration solution was replenished, and the pH in the tank was controlled so as not to deviate from the initial value. When 15 days have elapsed from the start of the treatment, the thinning amount varies and does not fall within the range of −1 μm to +1 μm. After that, the thinning amount varies continuously for up to 100 days, and proper management is not performed. It was. Moreover, when the density | concentration of the inorganic alkaline compound after 15-day progress was calculated | required, it was 10.6 mass% and was not an appropriate density | concentration value.

(Comparative Example 3)
A conductive pattern was obtained under the same conditions as in Example 1 except that a high-concentration replenisher (11 mass% sodium carbonate aqueous solution) was used instead of a liquid having the same concentration as the initial concentration. The number of processed sheets is 10th, 20th, 30th, etc., and the thinning amount varies immediately after neutralization titration, and the thinning amount does not fall within the range of -1 μm to +1 μm, and the maximum In some cases, the amount of thinning treatment was −2 μm.

  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 (uncrosslinked part)
2 Substrate 3 Crosslinked part of photocrosslinkable resin layer 4 Conductive layer 5 Insulating substrate 6 Micellarized photocrosslinkable resin layer

Claims (1)

  (A) a step of forming a photocrosslinkable resin layer on a substrate having a conductive layer on the surface, (b) an alkali metal carbonate, an alkali metal phosphate, an alkali metal hydroxide, an alkali metal silicate A step of thinning the photocrosslinkable resin layer with a resin layer thinning treatment solution comprising an aqueous solution containing 5 to 20% by mass of at least one inorganic alkaline compound selected from: (c) a circuit pattern exposure step; d) In the management method of the resin layer thinning treatment liquid in the method for producing a conductive pattern including the developing step and (e) the etching step in this order, the concentration of the inorganic alkaline compound in the resin layer thinning treatment solution is obtained by a neutralization titration method. A method for managing a resin layer thinning treatment liquid, wherein the concentration of the inorganic alkaline compound is maintained within a predetermined range by replenishing a liquid having the same concentration as the initial concentration.

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