JPS6120425B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a laminate and an apparatus therefor. Currently, industrial laminates are used in large quantities as general insulating boards for electronic components such as switches and volumes, and as copper-clad laminates for printed circuits covered with copper foil. Automation and labor saving in the process have progressed significantly, and the demand for thickness accuracy for laminates is increasing further. Normally, plate thickness accuracy depends on the characteristics of the thermosetting resin varnish used, such as specific gravity, viscosity, gel time, variations in base material weight, amount of resin impregnated during prepreg production, resin flow, and the material of cushion paper used during press molding. The resin content of the prepreg, which has the greatest effect on plate thickness accuracy, is influenced by many factors such as thickness accuracy, number of sheets, molding conditions, etc., but the present invention uses a special squeeze roll to reduce the resin content of the prepreg, which has the greatest effect on plate thickness accuracy, to create a laminate that can actually be continuously produced. The purpose is to provide a manufacturing method and device. Conventionally, the thickness of hot-press molded laminates has been determined by controlling the weight of multiple sheets of prepreg, and each sheet of prepreg has a more uniform resin content with less variation. In order to achieve this, the characteristics of the resin varnish, the weight of the base material, and the control of variations in resin flow have been taken, and improvements have been made to the selection of cushion paper and molding conditions during molding. Even if the conditions were devised, the actual situation was that the laminate was thin at the edges and thick at the center. In particular, when a laminate is formed using a multi-stage press, there is a large difference in the thickness of the board depending on the forming position within one book stage. That is, the laminate located on the hot platen side of the multi-stage press has a significant variation in plate thickness, while the laminate located in the center part away from the hot plate has less variation in plate thickness. For example, the thickness tolerance of paper base material and phenolic resin copper laminate is 1.6 ± 0.14 mm according to the JIS standard, but the variation in the thickness of the laminate formed on the heating plate side is close to this tolerance. Therefore, the variation in the thickness of the laminate formed in the central portion is very small. The present invention was made in view of the drawbacks of the conventional example, and its purpose is to reduce the variation range of the thickness of the entire lot of produced laminates, and to produce laminates with high thickness accuracy. To provide a manufacturing method and apparatus. The method for manufacturing a laminate of the present invention includes impregnating a sheet-like base material 1 such as paper, nonwoven fabric, or glass cloth with a thermosetting resin varnish 2 and drying it, so that the resin content on both sides changes from the resin content in the center. The method is characterized by forming a prepreg 3 that is 0.2 to 4% by weight larger than the amount of prepreg 3, and heating and press-molding the prepreg 3 by stacking the required number of sheets or stacking them together with other prepregs. Board manufacturing equipment is used for paper,
A resin impregnation tank 4 is used to soak a sheet-like base material 1 such as a non-woven fabric or a glass cloth to impregnate it with a thermosetting resin varnish 2, and a resin-impregnated resin-impregnated sheet base material 1 is pressed and held to determine the resin content. a pair of squeeze rolls 5 for adjusting the resin content, a dryer 8 for drying the sheet-like base material 1 whose resin content has been adjusted, and a pair for stacking the required number of prepregs 3 formed in this manner and forming them under heat and pressure. In this laminate manufacturing apparatus, the outer diameter of at least one of the squeeze rolls 5 is larger at the center than at both ends. The present invention will be explained in detail below. The sheet-like base material 1 is made of, for example, paper, non-woven fabric, glass cloth, etc., and is supplied to the laminate manufacturing apparatus in a wound state as shown in FIG. A resin impregnating tank 4 is filled with a thermosetting resin varnish 2, and squeeze rolls 5 are arranged in two upper and lower stages on the resin impregnating tank 4. The lower squeeze roll 5a is cylindrical, and about its lower half is immersed in the thermosetting resin varnish 2. The outer diameter of the upper squeeze roll 5b is changed in three steps so that the center part 6 has a large diameter and both end parts 7 have a small diameter. In addition, the squeeze roll 5' that was previously used
As shown in FIG. 4, both are cylindrical. A dryer 8 is arranged behind the squeeze rolls 5a and 5b. Then, the sheet-like base material 1 is rewound and immersed in the resin impregnation tank 4, so that the sheet-like base material 1 is sufficiently impregnated with the thermosetting resin varnish 2. Thereafter, the sheet-like base material 1 is pressed and held between squeeze rolls 5a and 5b, and excess thermosetting resin varnish 2 is squeezed out.
The resin content of the sheet-like base material 1 is adjusted to a predetermined amount. Next, this sheet-like base material 1 is introduced into a dryer 8 and dried to prepare a prepreg 3 for a laminate. In this prepreg 3, the resin content on both sides of the sheet-like base material 1 is 0.2 to 4% higher than the resin content in the central band.
It is formed so that it increases within a range of % by weight (hereinafter simply referred to as %). A plurality of sheets of this prepreg 3 are stacked and hot-pressed to form a laminate. In this case, a laminate may be formed by using the prepreg 3 according to the present invention in a part and heat-pressing the remaining part as a conventional prepreg (with a uniform resin content over the entire surface). be. In addition, from the above point, the range of resin impregnated amount was set at 0.2 to 4% because if it is less than 0.2%, it is within the range of variation in conventional drying methods and the effect is weak, and if it exceeds 4%, This is not practical because it causes local thickness unevenness and increases the variation in thickness. Next, we will list points that are desirable to consider when actually producing laminates. When carrying out the process, depending on the relationship between the specific gravity of the thermosetting resin varnish used and the degree to which the resin content is locally changed, the specific gravity of the varnish should be set high if the range of change is large, and if the range is small, the specific gravity of the varnish should be set high. It is better to keep it low. Naturally, in the case of multi-stage presses, the width of variation varies depending on the molding position within one book stage, so the hot platen side has a large local resin impregnation amount, and the center side has a small width. By using these properly, it becomes possible to improve the accuracy of thickness variations across the entire press slot. Regarding the relationship between resin content and resin flow, it is desirable to locally increase the degree of dryness on both sides of the sheet-like base material 1, which has a high resin content, and to reduce the resin flow. Further effects can be obtained if the sheet-like base material 1 is locally heated along the threading direction by infrared irradiation or the like in addition to the usual steam hot air drying. In the method for manufacturing a laminate of the present invention, a sheet-like base material such as paper, nonwoven fabric, or glass cloth is impregnated with a thermosetting resin varnish and dried, so that the resin content on both sides is equal to the resin content in the center. A prepreg that is 0.2 to 4% by weight larger than the content is formed, and the required number of prepregs are stacked or stacked together with other prepregs and hot-press molded, so the central part of the laminate becomes thick during hot-press molding. In addition, in the laminate manufacturing apparatus of the present invention, the sheet-like base material impregnated with resin is held by pressure. Of the pair of squeeze rolls that adjust the resin content,
Since the outer diameter of at least one squeeze roll is larger at the center than at both ends, it is possible to continuously increase the resin content on both sides of the sheet-like base material from the resin content in the central band. This allows efficient mass production of prepregs with locally varying resin contents. Next, examples of the present invention will be described. Example 1 A normal resol type phenolic resin varnish with a specific gravity of 0.995, a viscosity of 90 cps, and a gel time of 15 minutes 30 seconds was used.
Both ends of Mils thick kraft sheet base material
Impregnation coating was carried out using a squeeze roll designed to allow approximately 0.5% more resin content in only the 100 mm width than in other parts. The characteristics of the prepreg after drying are that the resin content is 49.8% on average at both ends and 49.3% on average in other parts.
% and resin flow were 10.4% and 10.1%, respectively. Stack 8 sheets of this prepreg and 1 piece of 35μ thick copper foil.
Place the sheet and place it in the center of one stage of a multi-stage press using a conventional method and heat-press mold it (100Kg/cm ² , 154℃, 60℃
) to obtain a laminate A. Comparative Example 1 Using the same varnish and sheet-like base material as above, impregnated with resin by a conventional method, the resin content was 49.2 to 49.4% regardless of the location, and the resin flow was in the range of 9.9 to 10.2%. After sorting, one sheet of 35μ thick copper foil was placed on eight of the sheets, and the sheets were molded at the same position in a multistage press under the same conditions as in Example 1 to obtain laminate B. Example 2 Four sheets of prepreg prepared according to Example 1 and four sheets of prepreg used in Comparative Example 1 were mixed and combined, one sheet of 35μ thick copper foil was placed in the same way, and the same position and the same conditions were pressed using a multistage press. A laminate C was obtained by molding. Example 3 When impregnating and coating a resol-type phenolic resin varnish with a specific gravity of 1.010, a viscosity of 105 cps, and a gel time of 14 minutes and 10 seconds using 10 mils thick kraft paper as a sheet-like base material, both sides of the sheet-like base material in the flow direction were coated. The edge 100 mm width was processed using the squeeze roll shown in Fig. 2, which was designed in advance so that the average resin content of the other parts could be increased by about 1.8% and the center band 200 mm width could be reduced by about 1%. In addition, infrared irradiation lamps were installed parallel to the flow direction in order to increase the amount of heating and drying on both sides of the sheet-like base material, approximately 100 mm wide, near the final step of the drying process. In this case, the characteristics of the prepreg are such that the resin content is averaged at both ends.
51.1%, resin flow 8.5%, center band has an average resin content of 48.4%, resin flow 9.1%, other areas have a resin content of about 49.3%, resin flow 9.3%
It was hot. Eight sheets of this were stacked in the same manner as in Example 1, one sheet of 35μ foil was placed, and molded by placing it on the upper hot platen side of a multistage press to obtain a laminate D. Comparative Example 2 Using the same resol type phenolic resin varnish and sheet-like base material as above, the resin content was 49.2 to 49.4.
% and a resin flow of 9.2% to 9.5%, a prepreg having an average composition of 9.2% to 9.5% was prepared and similarly molded by placing it on the upper hot platen side of a multistage press to obtain a laminate E. Example 4 Glass cloth (Nittobo WE-18G) was used as a sheet-like base material with bisphenol type epoxy resin varnish having a specific gravity of 1.095 and a stroke cure of 195 seconds, and both ends of the glass cloth (Nittobo WE-18G) were
Only the 80 mm width was impregnated and coated using a squeeze roll designed to increase the resin content by about 1.2% compared to other parts. Regarding the prepreg properties after drying, the resin content was 39.1% at both ends and an average of 37.9% at the other parts. 9 sheets of this prepreg were stacked, one sheet of 35 μ thick copper foil was placed, and placed in the center of one stage of a multi-stage press using a conventional method, and hot-press molded (20 Kg/cm ² , 170°C, 60 minutes).
A laminate F was obtained. Comparative Example 3 Using the same bisphenol type epoxy resin varnish and sheet-like base material as in Example 4, it was impregnated with resin by a conventional method, and the resin content was 37.6 to 37.6% regardless of the location.
One sheet of 35μ thick copper foil was placed on eight sheets of prepreg falling within the range of 38.2%, and molded at the same position in the multi-stage press under the same conditions as in Example 4 to obtain a laminate G.

[Table] (Measurement method for plate thickness) As shown in Figure 3, measure 45 points in total in 3 rows (a, b, c), 15 points each, on one laminate plate, average the measured values, and then Thickness. In this case, the distance h between rows a and c and the end of the laminate is 10 mm. Next, in the same way, the variation in the thickness of one laminate is determined as a from the difference between the measured values at 45 points. In addition, the minimum value was set as Xmin and the maximum value was set as Xmax among the measured values at 45 points, and the thickness range R was calculated from Xmax - Xmin. In FIG. 3, arrow A indicates the vertical direction of the laminate, and black dots indicate measurement points. The thickness measuring device used was a laminate thickness statistical processing device KH-75 manufactured by Sun Electronics Co., Ltd.

[Brief explanation of the drawing]

Fig. 1 is a schematic structural diagram of an embodiment of a laminate manufacturing apparatus according to the present invention, Fig. 2 is a front view of an embodiment of a squeeze roll used in the same, and Fig. 3 shows measurement points in the present invention. A front view of the laminate, and FIG. 4 is a front view of a conventional squeeze roll. 1... Sheet-like base material, 2... Thermosetting resin varnish,
3... Prepreg, 4... Resin impregnation tank, 5... Squeeze roll, 6... Center part of squeeze roll, 7... End part of squeeze roll, 8... Dryer.

Claims (1)

[Claims] 1. A sheet-like base material such as paper, nonwoven fabric, or glass cloth is impregnated with a thermosetting resin varnish and dried so that the resin content on both sides is higher than the resin content in the center part.
A method for producing a laminate, which comprises forming a prepreg 0.2 to 4% larger by weight, and forming a required number of prepregs by stacking them or stacking them together with other prepregs under heat and pressure. 2 A resin impregnation bath for dipping sheet-like substrates such as paper, non-woven fabric, and glass cloth to impregnate them with thermosetting resin varnish, and a resin-impregnating bath for press-clamping the sheet-like substrates after resin impregnation to reduce the resin content. A pair of squeeze rolls for adjusting the resin content, a dryer for drying the sheet-like base material whose resin content has been adjusted, and a pair of heating plates for stacking the required number of prepregs formed in this way and forming them under heat and pressure. 1. A laminate manufacturing apparatus comprising: an outer diameter of at least one of the squeeze rolls, wherein the outer diameter of at least one squeeze roll is larger at the center than at both ends.