JP2005307080A - Method for manufacturing prepreg and laminated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a prepreg with reduced warpage in a continuous production process of the prepreg that can reduce warpage of a substrate after drying without lowering production efficiency, and to provide a method for manufacturing a laminated sheet using the prepreg manufactured by the method. <P>SOLUTION: In this method for manufacturing prepreg, a resin content in a substrate or a thickness of a resin layer is measured after a process adjusting a resin varnish content. Depending on the resulting measured value, the resin varnish content is adjusted on at least one surface of the substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method capable of continuously and efficiently producing a prepreg with reduced warpage, and a method for producing a laminate using the prepreg obtained by the method.

  In producing the prepreg, in order to achieve efficient production, the substrate is impregnated with the resin varnish and semi-cured continuously and then cut. That is, as shown in FIG. 1, a substrate such as a glass cloth is immersed in a resin varnish while being transferred using a transfer means such as a roll, and the amount of the resin varnish is adjusted through a squeeze roll and then semi-cured with a dryer. After that, it is cut into a desired size or wound on a roll.

  However, in such a continuous production process, warping may occur in the prepreg that has undergone the drying process, particularly due to an imbalance in the amount of resin varnish on the front and back surfaces of the substrate. Since the prepreg that has warped may cause a failure of a laminate using the warp and eventually a mounting substrate, the difference in the amount of resin on both surfaces of the base material should be made uniform to reduce warpage.

  In recent years, warping of the prepreg is more likely to occur, and this problem is particularly noticeable. That is, due to the recent increase in the number of printed circuit boards and the increase in the soldering temperature when electronic components are mounted, the prepreg is required to have a further low thermal expansion, so an inorganic filler such as silica is added. However, when the base material is impregnated with the resin varnish to which the inorganic filler is added, since the penetration into the base material is inferior to the resin varnish without the filler, an imbalance in the amount of resin tends to occur between the front and back sides of the base material. As a result, warping occurs after drying, causing a catch in a subsequent process such as a printed board processing process, resulting in an increase in process defects.

  Therefore, in the technique disclosed in Patent Document 1, in order to reduce the warpage of the prepreg, the substrate is once dipped on both sides of the substrate by dipping in the resin varnish as in the continuous manufacturing method shown in FIG. Instead of coating the varnish on the front and back surfaces of the front and back surfaces separately, the unevenness of the resin amount is reduced. According to this technique, a uniform prepreg can surely be produced and an excellent laminated sheet can be provided. However, there is a demand for a more efficient continuous production method. Further, it is considered that the warp can be more effectively reduced by detecting the occurrence of warp of the prepreg and adjusting the manufacturing conditions according to the result.

  As a technique for directly measuring the warpage of the prepreg, there is a technique using a laser displacement meter as in Patent Document 2. However, this technology measures the warpage of prepregs and laminates as products, and can not be used in a continuous manufacturing process, but can quickly feed back measurement results to change manufacturing conditions. is not. That is, in the process of continuously producing prepreg, since the substrate is transferred while being applied with tension, accurate measurement cannot be performed during the production process. As a result, since it is necessary to measure with a finally cut sample, even if a defect is detected, the manufactured prepreg is unavoidable until the resin amount is adjusted thereafter.

By the way, the base material, which is a material of the prepreg, is subjected to processing such as removing warp yarn at the end (feathered edge) or applying a polyester resin in order to prevent the yarn from falling off during the manufacturing process. (Patent Document 3). As a result, since the amount of impregnation of the resin varnish into the substrate is reduced, the resin varnish adheres so as to rise at the end of the substrate (Patent Document 4). Therefore, in the technique of claim 6 of Patent Document 4, the end portion of the base material is cut and removed.
Japanese Patent Laid-Open No. 5-200747 (Claims) Japanese Patent Laid-Open No. 11-6726 (Claims) Japanese Patent Laid-Open No. 11-207741 (paragraph [0004], FIG. 4) JP 2001-150432 A (Claim 6, paragraph [0006])

  As described above, conventionally, manufacturing conditions for reducing the prepreg warpage have been studied. However, considering the actual implementation, it is ideal that the fundamental part of the existing manufacturing equipment should not be changed as much as possible, and it is desirable that detected defects can be fed back quickly to changes in manufacturing conditions. .

  Therefore, the problem to be solved by the present invention is to reduce the warpage of the substrate after drying without sacrificing the production efficiency in the continuous production process of the prepreg, and can efficiently produce the prepreg with reduced warpage. It is to provide a method.

  Another object of the present invention is to provide a method for producing a laminate using the prepreg produced by the method.

  In order to solve the above-mentioned problems, the present inventors have conducted earnest research on a method capable of reducing the warp without reducing the continuous production efficiency of the prepreg. The present invention has been completed by finding that an imbalance of a certain amount of resin can be measured without waste during the production process and that the measurement result can be quickly fed back to adjust the production conditions.

  That is, the method for producing a prepreg according to the present invention includes a step of impregnating at least a substrate with a resin varnish (hereinafter referred to as “resin varnish impregnation step”), a step of adjusting the amount of resin varnish (hereinafter referred to as “resin varnish amount adjustment step”). ) And a step of drying and semi-curing the substrate impregnated with the resin varnish (hereinafter referred to as “semi-curing step”). The resin amount or the resin layer thickness of the material is measured, and the amount of the resin varnish on at least one surface of the substrate is adjusted according to the value.

  In the above manufacturing method, the resin amount of the base material is measured as the amount of resin scraped by a scraping jig in a certain time, and the resin layer thickness is measured by scraping the resin layer with a scraping jig. It is preferable to do. This is because the scraping jig can be used as an effective means in the present invention.

  In the said manufacturing method, it is preferable to adjust the quantity of the resin varnish in at least one surface of a base material according to the difference of the resin amount or resin layer thickness in the surface of a base material, and a back surface. Recognizing the cause of prepreg warpage as an imbalance in the amount of resin on the front and back surfaces of the substrate, and obtaining such an imbalance as a quantitative value, and promptly feeding this back to changes in manufacturing conditions It is.

  The difference in the resin amount or the resin layer thickness is preferably obtained from an average value obtained by measuring the resin amount or the resin layer thickness at at least two positions on the front surface and the back surface of the substrate. It is intended for more accurate measurement.

  Moreover, the manufacturing method of the laminated board which concerns on this invention laminates | stacks the prepreg manufactured by the said method, distribute | arranges copper foil to the at least single side | surface of the said laminated body, and heat-presses.

  According to the method for producing a prepreg according to the present invention, warpage can be reduced without reducing the efficiency of a continuous production process, and a defect detected in the production process is detected as a resin amount or a resin layer thickness. Can be fed back promptly to adjust the manufacturing conditions. Therefore, the method of the present invention is extremely industrially regarded as being able to efficiently produce a prepreg or a laminate with reduced warpage even under conditions where a filler is added to the resin varnish and warping of the prepreg is likely to occur. Useful.

  Hereinafter, embodiments of the present invention and effects thereof will be described.

  The method for producing a prepreg according to the present invention includes at least a resin varnish impregnation step, a resin varnish amount adjustment step, and a semi-curing step, and after the resin varnish amount adjustment step, the resin amount or resin layer thickness of the substrate is determined. The gist is to adjust the amount of the resin varnish on at least one surface of the substrate in accordance with the measured value.

  As a general continuous production method of a prepreg including a resin varnish impregnation step, a resin varnish amount adjustment step, and a semi-curing step, a known method schematically shown in FIG. 1 may be applied as it is. Specifically, first, the resin varnish in the impregnation tank 1 is continuously impregnated while transferring a substrate such as a glass cloth by a transfer means such as a roll (resin varnish impregnation step). In addition, 2 in FIG. 1 is a dip roll, and has a role which makes a base material fully immerse in a resin varnish, or changes the advancing direction of a base material.

  The component structure of the resin varnish used in the present invention is not particularly limited. For example, a resin in which a thermosetting resin such as an epoxy resin, a curing agent, a curing accelerator, a filler, and other additives are dissolved or uniformly dispersed in a solvent may be used.

  The base material impregnated with the resin varnish is subsequently passed between the squeeze rolls 3 to adjust the amount of the resin varnish on the surface of the base material or to make the amount of unevenness uniform (resin varnish amount adjusting step). . Such adjustment and the like will be described with reference to FIG. Excess resin varnish is adhered to the surface of the base material immediately after leaving the impregnation tank 1, or the amount of resin varnish present on the surface is uneven due to dripping. Furthermore, an imbalance in the amount of the resin varnish may occur between the front surface and the back surface of the base material, and this may be the main cause of warping of the prepreg. Therefore, when warping occurs in the product prepreg, the distance between the squeeze roll 3 and the base material is changed by moving at least one of the squeeze rolls 3 in the direction of the arrow in FIG. It has been performed to reduce the unevenness. In some cases, the distance between the squeeze roll 3 and the base material may be changed by moving the position of the dip roll 2.

  Then, the resin is semi-cured to the B stage by passing through the dryer 4 (semi-curing step). And after removing a base-material edge part by the edge part cutting removal means 5, the base material is cut | disconnected to a desired magnitude | size by the cutting means 6, and a prepreg is obtained. Or you may wind up on a roll etc., without cut | disconnecting.

  In the present invention, the resin amount or the resin layer thickness of the substrate is measured after the resin varnish amount adjusting step during the prepreg continuous manufacturing step. 3 and 4 show schematic diagrams of the measuring method using the scraping jig.

  The scraping jig is a member for scraping off the resin during the semi-curing process from the substrate, and the material thereof is not particularly limited. One end of the scraping jig is fixed, while the other end can come into contact with or away from the base material, and the resin can be scraped off at intervals. However, when measuring the resin layer thickness, the resin layer may be scraped off continuously without dividing time.

  In the continuous manufacturing process of the prepreg, after the semi-curing process, the edge part of the substrate is generally cut and removed as in the technique described in Patent Document 4. Therefore, in the present invention, it is preferable to scrape the resin layer at the end of the base material to be cut and removed (in FIG. 3, outside the dotted line). This is because removing the resin layer at this portion does not affect the quality of the product prepreg.

  The resin amount or the resin layer thickness of the substrate is measured at any point after the resin varnish amount adjusting step. In the present invention, the measurement result is fed back to the conditions of the resin varnish amount adjusting step to stabilize the product quality, so that even if it is measured before the resin varnish amount adjusting step, it does not make sense. The measurement is preferably performed before the end of the substrate is cut off. Measurement may be performed at the edge of the base material after being cut and removed, but the measurement result is reflected in the production conditions (adjustment of the amount of resin varnish) more quickly when measurement is performed in the course of the continuous production process. Because it can and is efficient. In addition, the resin scraped off from the semi-curing process before the edge cutting and removing process adheres to (1) the scraping jig, (2) falls from the scraping jig, or (3) the resin layer. It will be peeled off from the substrate while maintaining the shape.

  In other words, from the resin varnish dipping process to the initial stage of the semi-curing process, the fluidity of the resin varnish remains high, so the scraped resin adheres to the scraping jig or drops from the scraping jig. To do. In this case, the amount dropped is received by the tray 8 in FIG. 3, and the amount attached to the scraping jig is removed, and the scraped jig is removed, and then the scraped resin amount (weight) is measured. Good. Alternatively, as shown in FIG. 5, for example, a scraping jig made of a fixed portion and a moving portion (preferably a tray-shaped one is used so that the scraped resin can be held) is used. The moving part may be moved in the same direction as the transfer direction with respect to the substrate and faster than the transfer speed, and the resin layer between the fixed part and the moving part may be scraped off to measure the resin amount.

  Further, the substrate immersed in the resin varnish in the impregnation tank 1 is heated by the dryer 4. At this time, the solvent in the resin varnish adhering to the substrate is gradually distilled off, and the resin varnish is semi-cured. As a result, the fluidity of the resin layer decreases. Therefore, in the latter half of the semi-curing step and thereafter, the semi-curing of the resin layer is almost completed, and thus the scraped resin is peeled off from the substrate while maintaining the shape of the resin layer. In this case, the scraped resin amount (weight) may be measured, or the resin layer thickness may be measured. However, in this case, the resin layer may not be separated even if the scraping jig is separated from the base material. Therefore, consider the measurement position, or remove the resin layer continuously to increase the timely resin layer thickness. It is necessary to measure. Further, when the semi-curing is completely completed, the scraped resin may be powdered and scattered, so the measurement position needs to be before (for example, immediately after the drying step).

  In the present invention, it is preferable to measure the resin amount at a certain time or the resin layer thickness at a certain time point on the front surface and the back surface of the base material, and obtain the difference. The largest cause of prepreg warpage is the difference in resin amount or resin thickness between the front and back surfaces of the substrate, and by adjusting the amount of resin varnish on at least one surface of the substrate according to this difference, the warp This is because it is possible to reduce this. Therefore, the measurement conditions for one surface must be the same as for the other surface. For example, the measurement position on one surface must be the top, bottom, left, and right positions opposite the other surface (back) via the base material, and the shape of the scraping jig to be used is the same And shall be.

  In measuring the amount of resin, the resin scraping time must naturally be the same on the front surface and the back surface. In addition, the resin thickness is measured at the same time regardless of whether the resin layer is scraped in a certain time or continuously. Furthermore, when calculating the difference in the resin amount or resin thickness between the front and back surfaces of the substrate, measure the resin amount or resin thickness at two or more locations on the front and back surfaces, calculate the average value, and then calculate the difference. Is preferable. This is to obtain more accurate results.

  If it is necessary to increase or decrease the amount of resin varnish on at least one surface of the base material after measuring the resin amount or the resin layer thickness, it is possible to quickly warp by adjusting the distance between the squeeze roll and the base material. The production of a prepreg having the above can be suppressed. That is, since the resin varnish contains a solvent and volatilizes in the dryer, if an imbalance occurs in the amount of the resin varnish on both sides of the substrate, the degree of shrinkage of the surface with the larger amount increases and warpage occurs. Result. Therefore, the amount of the resin varnish on the surface can be reduced by bringing the squeeze roll inside the warp of the substrate surface closer to the substrate. As a result, in the past, a sample was taken from the product prepreg to measure the warpage, and since the manufacturing conditions were changed on that, a loss was inevitably generated. Can be quickly reflected on the manufacturing conditions, and the loss can be remarkably reduced. In particular, in the present invention, the measurement position of the resin amount and the resin thickness is close to the dip roll which is the main part for adjusting the resin varnish amount (during the drying process, etc.), so that the measurement result can be adjusted more quickly. It becomes possible to reflect.

  The movement distance when moving the squeeze roll can be reduced more efficiently if the difference in the resin amount or resin layer thickness between the front and back surfaces of the base material is grasped as a quantitative value and adjusted according to that value. .

  The prepreg obtained by the present invention can be made into a laminate by laminating a plurality of prepregs, and further heat-pressing a metal foil such as a copper foil on both upper and lower surfaces or one surface thereof. Since this laminated board is made of a prepreg with reduced warpage, the warpage is naturally suppressed.

It is the figure which showed typically the manufacturing method of the prepreg including the process of impregnating a base material with a resin varnish, and the process of drying and semi-hardening the base material which impregnated the resin varnish. It is a figure for demonstrating the effect | action of a squeeze roll. It is a schematic diagram which shows the one aspect | mode which scrapes off resin with a scraping jig | tool. It is a schematic diagram which shows the one aspect | mode which scrapes off resin with a scraping jig | tool. It is a schematic diagram which shows the one aspect | mode which scrapes off resin with a scraping jig | tool.

Explanation of symbols

1: Impregnation tank (having resin varnish)
2: Dip roll 3: Squeeze roll 4: Dryer 5: End cutting / removing means Cutting means 6: Cutting means 7: Scraping jig 8: Trays 9: End of base material to be cut and removed

Claims (8)

Including a step of impregnating at least a base material with a resin varnish, a step of adjusting the amount of the resin varnish (hereinafter referred to as “resin varnish amount adjustment step”), and a step of drying and semi-curing the base material impregnated with the resin varnish. A method for producing a prepreg,
After the resin varnish amount adjustment step, measure the resin amount or resin layer thickness of the base material,
According to the value, the amount of the resin varnish on at least one surface of the substrate is adjusted.   2. The method for producing a prepreg according to claim 1, wherein the resin amount of the base material is measured as a scraped resin amount in a predetermined time by a scraping jig.   The method for producing a prepreg according to claim 1, wherein the resin layer thickness is measured by scraping the resin layer with a scraping jig.   3. The method for producing a prepreg according to claim 1, wherein the amount of the resin varnish on at least one surface of the substrate is adjusted according to the difference in the amount of resin between the front surface and the back surface of the substrate.   The method for producing a prepreg according to claim 1 or 3, wherein the amount of the resin varnish on at least one surface of the substrate is adjusted according to a difference in resin layer thickness between the front surface and the back surface of the substrate.   The manufacturing method according to claim 4, wherein the amount of resin is measured at at least two locations on each of the front and back surfaces of the substrate, and the difference between the resin amounts on the front and back surfaces of the substrate is determined from the average value. Method.   6. The prepreg according to claim 5, wherein the thickness of the resin layer is measured at at least two positions on each of the front surface and the back surface of the substrate, and the difference between the resin layer thicknesses on the front surface and the back surface of the substrate is determined from the average value. Manufacturing method.   A method for producing a laminate comprising laminating a plurality of prepregs produced by the method according to claim 1, placing a copper foil on at least one side of the laminate and heating and pressing.

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