JP3867673B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

【００４８】
表１から明らかなように、実施例１、２は比較例よりも層間ずれが小さくなった。また、実施例１は実施例２に比べて成形性が高くなった。
【００４９】
【発明の効果】
上記のように本発明の請求項１の発明は、プリプレグを介して複数枚の内層材を重ね、プリプレグを隣接する内層材に部分的に溶着して隣り合う内層材同士を仮止めし、最外の内層材の表面にさらにプリプレグを介して外層材を重ねた後、加熱加圧成形により各プリプレグを隣接する内層材及び外層材に全体的に溶着することによって内層材と外層材とを積層する多層プリント配線板の製造方法において、上記の加熱加圧成形を加熱加圧成形の開始から０．５〜１．０ＭＰａの１次圧力で行った後、１．５〜２．５ＭＰａの２次圧力で行い、１次圧力から２次圧力への昇圧は２０〜３０分間かけて行い、１次圧力から２次圧力への到達のタイミングは、製品温度が１〜３℃／分にて昇温している間で且つプリプレグの樹脂が最低溶融粘度に達する時点からその１０分前までの間であるので、加熱加圧成形の際の圧力を徐々に上げてプリプレグの樹脂が硬化する直前に２次圧力をプリプレグや内層材や外層材にかけるようにすることによって、内層材の位置ずれを防止することができ、内層材に形成された回路パターンの位置ずれを少なくして高精度の回路パターンを有する多層プリント配線板を製造することができるものである。
【００５０】
また本発明の請求項２の発明は、プリプレグと内層材と外層材とを重ねたものを加熱加圧成形の前に減圧状態にするので、内層材の回路パターンの形状やプリプレグの吸湿などに起因する成形ボイドの発生を低減することができ、良好な成形性を確保することができるものである。
【図面の簡単な説明】
【図１】本発明の実施の形態を示し、圧力設定と温度設定と溶融粘度カーブと製品温度との変化を示すグラフである。
【図２】同上の溶着工程を示し、（ａ）は概略の側面図、（ｂ）は概略の平面図である。
【図３】同上の加熱加圧成形工程を示す概略の側面図である。
【符号の説明】
１ プリプレグ
２ 内層材
３ 外層材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a multilayer printed wiring board having a conductor layer such as a large number of circuit patterns, and in particular, a method suitably used for producing a multilayer printed wiring board having 10 or more conductor layers. is there.
[0002]
[Prior art]
Conventionally, a multilayer printed wiring board is manufactured by laminating a plurality of printed wiring boards and metal foils. In manufacturing such a multilayer printed wiring board, mass lamination using pin lamination method or eyelet (caulking) method is used to accurately align the position of conductor layers such as circuit patterns between the laminated printed wiring boards. Construction method is adopted. However, in this case, since a clearance is generated between the pin or eyelet and the hole of the printed wiring board, the printed wiring board moves by the amount of the clearance. It was difficult to produce a multilayer printed wiring board having the same.
[0003]
Thus, it has been proposed to manufacture a multilayer printed wiring board by a welding method different from the mass lamination method (see, for example, Patent Document 1). In this welding method, a plurality of inner layer materials are stacked via a prepreg, the prepreg is partially welded to the adjacent inner layer material by heating and pressing, and the adjacent inner layer materials are temporarily fixed, and the outermost inner layer material After the outer layer material is further stacked on the surface via the prepreg, the inner layer material and the outer layer material are laminated by welding each prepreg to the adjacent inner layer material and outer layer material by heating and pressing. A printed wiring board having a conductor layer such as a circuit pattern on both sides or one side can be used as the inner layer material, and a metal foil such as a copper foil or a conductor layer such as a circuit pattern on both sides or one side can be used as the outer layer material. A printed wiring board having the following can be used.
[0004]
And in the above welding method, the prepreg is partially welded to the adjacent inner layer material, and the adjacent inner layer materials are temporarily fixed, so that when each prepreg is entirely welded to the adjacent inner layer material and outer layer material, In heat and pressure molding, the inner layer material can be made difficult to move in a direction parallel to the surface direction (direction perpendicular to the pressing direction), and the positional displacement between layers is less likely to occur, and pins and eyelets are not used. Therefore, it is possible to prevent the positional displacement between the layers due to the clearance between the pin or eyelet and the hole of the printed wiring board.
[0005]
[Patent Document 1]
JP 2001-203453 A (Claims etc.)
[0006]
[Problems to be solved by the invention]
However, in the welding method as described above, at the time of heat and pressure molding performed when each prepreg is entirely welded to the adjacent inner layer material and outer layer material, the temporarily welded portion is remelted and the inner layer materials are In some cases, the temporary fixing may be removed, and the multilayer printed wiring board having a highly accurate circuit pattern may not be manufactured due to the displacement of the inner layer material. In particular, when manufacturing a multilayer printed wiring board having an inner layer circuit pattern of 10 layers or more, since 5 or more inner layer materials are overlapped, each inner layer material is displaced one by one when the inner layer materials are displaced in substantially the same direction. Even if the positional deviation is small, the deviation between the layers becomes very large, and it is very difficult to manufacture a multilayer printed wiring board having a highly accurate circuit pattern.
[0007]
The present invention has been made in view of the above points, and provides a method for manufacturing a multilayer printed wiring board capable of manufacturing a multilayer printed wiring board having a high-accuracy circuit pattern by preventing displacement of an inner layer material. It is intended to do.
[0008]
[Means for Solving the Problems]
In the method for manufacturing a multilayer printed wiring board according to claim 1 of the present invention, a plurality of inner layer materials 2 are stacked via a prepreg 1, and the prepreg 1 is partially welded to the adjacent inner layer material 2 to be adjacent inner layer materials. 2 and 2 are temporarily fixed, and after the outer layer material 3 is further stacked on the surface of the outermost inner layer material 2 via the prepreg 1, the prepreg 1 is applied to the adjacent inner layer material 2 and outer layer material 3 by heat and pressure molding. In the method for manufacturing a multilayer printed wiring board in which the inner layer material 2 and the outer layer material 3 are laminated by welding as a whole, the above-described heating and pressing is performed at 0.5 to 1.0 MPa from the start of heating and pressing. After the primary pressure, the secondary pressure is 1.5 to 2.5 MPa, and the primary pressure to the secondary pressure is increased over 20 to 30 minutes. The primary pressure to the secondary pressure is reached. The timing of the product is raised at a product temperature of 1-3 ° C / min It is characterized in that and prepreg resin is between up to ten minutes before the time of reaching the minimum melt viscosity between.
[0009]
In addition to claim 1, the method for producing a multilayer printed wiring board according to claim 2 of the present invention is characterized in that a reduced pressure state is provided before heat-press molding.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0011]
The prepreg 1 used in the present invention is formed in the same manner as in the prior art, and includes a base material containing a thermosetting resin composition as a resin. As the base material of the prepreg 1, inorganic fibers such as glass, organic fibers such as polyester, polyamide, polyacryl, and polyimide, and woven fabrics, nonwoven fabrics, and papers of natural fibers such as cotton can be used. A woven fabric (glass cloth) such as glass fiber is preferable because it is excellent in heat resistance and moisture resistance and the effects of the present invention can be easily obtained. Moreover, although the thickness of a base material is not specifically limited, For example, the thing of 0.06-0.20 mm can be used.
[0012]
Further, as the thermosetting resin composition of the prepreg 1, an epoxy resin type, a phenol resin type, a polyimide resin type, an unsaturated polyester resin type, a polyphenylene ether type, etc. alone, a modified product, a mixture, etc. All resin compositions can be used.
[0013]
This thermosetting resin composition contains a thermosetting resin as an essential component, and may contain a curing agent, a curing accelerator, an inorganic filler, and the like of the thermosetting resin as necessary. Note that a thermosetting resin composition having a low self-curing property such as an epoxy resin needs to contain a cured product for curing the resin. Moreover, when a thermosetting resin composition is an epoxy resin type | system | group, the balance of an electrical property and adhesiveness is favorable and preferable.
[0014]
When using an epoxy resin as the thermosetting resin composition of the prepreg 1, examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and phenol novolac type epoxy resin. Bisphenol A novolac type epoxy resin, bisphenol F novolac type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, brominated bisphenol A type epoxy resin, and the like. Examples thereof include an epoxy resin that has been made flame retardant by partially halogenating. In the epoxy resin-based thermosetting resin composition, it is preferable to mix one or more of the above epoxy resins so that the halogen content with respect to the total amount of the resin is 15 to 20% by mass. .
[0015]
Examples of the curing agent contained in the epoxy resin-based resin composition include amide-based curing agents such as dicyandiamide and aliphatic polyamide, amine-based curing agents such as ammonia, triethylamine, and diethylamine, phenol novolac resins, and cresols. Examples thereof include phenolic curing agents such as novolak resin and p-xylene-novolak resin, and acid anhydrides. In the epoxy resin-based thermosetting resin composition, a mixture of one or more of the above curing agents is contained in an amount of 1.5 to 5% by mass based on the total amount of the thermosetting resin composition. It is preferable.
[0016]
Moreover, as a hardening accelerator, an imidazole compound etc. can be used. When especially 2-ethyl-4-methylimidazole (2E4MZ) is mix | blended, hardening at the time of the preservation | save of a resin composition will become difficult to advance, and preservability is good. It can improve and is preferable at the point which can maintain a varnish life. In the epoxy resin-based thermosetting resin composition, it is preferable that 2E4MZ is contained in an amount of 0.01 to 0.05% by mass with respect to the total amount of the thermosetting resin composition.
[0017]
Examples of the inorganic filler that can be contained in the thermosetting resin composition include inorganic powder fillers such as silica, calcium carbonate, aluminum hydroxide, and talc, glass fibers, pulp fibers, synthetic fibers, and ceramics. Examples thereof include fibrous fillers such as fibers, and these inorganic fillers can be blended in the range of 0 to 80% by mass with respect to the total amount of the thermosetting resin composition.
[0018]
The method for producing the prepreg 1 from the thermosetting resin composition and the base material is not particularly limited. For example, the base material is immersed in a resin varnish whose viscosity is adjusted with a solvent. After impregnation, if necessary, it is obtained by heat drying and semi-curing. For example, when using an epoxy resin-based thermosetting resin composition, 120 to 200 ° C. for 3 to 5 minutes Heat drying is possible. Examples of the solvent that can be used to adjust the viscosity of the thermosetting resin composition include amides such as N, N-dimethylformamide, ethers such as ethylene glycol monomethyl ether, ketones such as acetone and methyl ethyl ketone, methanol, Examples include alcohols such as ethanol, aromatic hydrocarbons such as benzene and toluene, and a mixture of one or more of these solvents in a range of 5 to 60% by mass with respect to the total amount of the resin varnish. Can be blended.
[0019]
Moreover, it is preferable that the resin amount in the prepreg 1 is 40 to 70 parts by mass with respect to 100 parts by mass of the prepreg 1 (total mass of the thermosetting resin composition and the base material). When the amount is less than 40 parts by mass, bubbles may remain inside the base material when the laminate 15 is heat-pressed and the electrical characteristics may be deteriorated. When heating and pressurizing, there are many resin flows, and the dispersion | variation in board thickness may become large.
[0020]
As the inner layer material 2 and the outer layer material 3 used in the present invention, a known printed wiring board (such as FR-4) having a conductor layer such as a circuit pattern on one side or both sides of the insulating layer can be used. Moreover, although the inner layer material 2 and the outer layer material 3 can use the thing of thickness 0.06-0.30mm, it is not limited to this. Furthermore, as the outer layer material 3, a known metal foil such as a copper foil having a thickness of 0.009 to 0.070 mm can be used.
[0021]
And the manufacturing method of the multilayer printed wiring board of this invention is performed as follows. First, a plurality of inner layer materials 2 are stacked via the prepreg 1. At this time, when the inner layer material 2 having a circuit pattern on both surfaces is used and five or more inner layer materials 2 are used, a multilayer printed wiring board having an inner layer circuit pattern of 10 layers or more can be manufactured. Further, the adjacent inner layer material 2 and the prepreg 1 are in close contact with each other over the entire surface, and the inner layer material 2 is overlapped at an accurate position so as not to be displaced in a direction parallel to the surface direction. Further, by providing the laminating guide hole 10 at the end of each inner layer material 2 and each prepreg 1 and disposing the fixing pin 11 so as to penetrate the laminating guide hole 10, the above-mentioned positional deviation is caused in the inner layer material 2. It does not occur.
[0022]
As described above, a plurality of the prepregs 1 and the inner layer material 2 are alternately stacked, and then, as shown in FIGS. Are partially welded to the adjacent inner layer material 2 to temporarily fix the adjacent inner layer materials 2 and 2 together. Here, in order to heat and press a part of the prepreg 1, a plurality of heater jigs 13 are brought into contact with the surface end portions of the inner layer material 2 located on the uppermost side and the inner layer material 2 located on the lowermost side. The heater jigs 13 arranged in the vertical direction are sandwiched between the plurality of prepregs 1 and the inner layer material 2 and heated while being pressed, whereby the heater of the prepreg 1 is heated. A portion (end portion) sandwiched between the jigs 13 is cured, and the prepreg 1 is partially welded to the adjacent inner layer material 2 to temporarily fix the adjacent inner layer materials 2 and 2 together. And the inner-layer core material 14 can be formed by temporarily fixing the prepreg 1 and the inner-layer material 2 which were piled up in this way.
[0023]
As the heater jig 13, it is preferable to use a heater jig having a width in the range of 2 to 20 mm in contact with the inner layer material 2. At this time, when an epoxy resin-based thermosetting resin composition is used as the prepreg 1, the pressure applied by the heater jig 13 is preferably 0.4 to 1 MPa. The heater jig 13 can be exemplified by applying ultrasonic vibration to the prepreg 1 and heating it. The heating temperature is 170 to 300 ° C., and the heating and pressing time is 10 to 120 seconds. Is preferred. Moreover, when applying ultrasonic vibration, it is preferable that the frequency shall be 10-50 kHz, and pressurization and ultrasonic vibration application time shall be 10-120 seconds.
[0024]
After forming the inner layer core material 14 as described above, the outer layer material 3 is further stacked on the surface of the inner layer core material 14, that is, on the surfaces of both outermost inner layer materials 2 via another prepreg 1. Here, the prepreg 1 and the outer layer material 3 are stacked with the fixing pin 11 being removed from the stacking guide hole 10 of the inner layer core material 14. Further, the surface of the inner layer core material 14, the prepreg 1 and the outer layer material 3 are in close contact with each other over the entire surface.
[0025]
After the prepreg 1 and the outer layer material 3 are stacked on the surface of the inner layer core material 14 as described above, all the prepregs 1 disposed between the adjacent inner layer materials 2 and between the inner layer material 2 and the outer layer material 3 are By curing by heating and pressing, the prepreg 1 and the inner layer material 2 adjacent thereto are welded as a whole, and the prepreg 1 and the outer layer material 3 adjacent thereto are welded as a whole. Thus, a multilayer printed wiring board can be formed by integrating and laminating a plurality of inner layer materials 2 and outer layer materials 3 by curing the prepreg 1.
[0026]
A laminate 15 in which the inner layer core material 14, the prepreg 1 and the outer layer material 3 are overlapped is, for example, as shown in FIG. As shown in FIG. 1, molding is performed while the pressure setting applied to the laminate 15 by the pressure plate 16 and the temperature setting of the pressure plate 16 are changed over time.
[0027]
The pressure setting by the pressure plate 16 at the time of heat and pressure molding is shown by the curve A in FIG. 1, and after the heat pressure and pressure molding is performed at a constant primary pressure (range A1), 20 The pressure is increased from the primary pressure to the secondary pressure over a period of ˜30 minutes (in the range of A2, t2−t1 = 20 to 30 minutes), and then a certain amount until the end of the heat and pressure molding The pressure is changed so as to be performed at the secondary pressure (range A3). In addition, the timing of arrival from the primary pressure to the secondary pressure (time t2 when the secondary pressure is reached) is the product temperature (the temperature of the laminate 15 shown by the curve C) of 1 to 3 ° C./min. Between the time t3 when the resin of the prepreg 1 (thermosetting resin composition) reaches the minimum melt viscosity and the time 10 minutes before the minimum melt viscosity is reached. That is, in the heat-press molding of the laminate 15, while the product temperature is rising at 1 to 3 ° C. per minute, and 10 minutes when the resin (thermosetting resin composition) of the prepreg 1 reaches the minimum melt viscosity. The pressure is allowed to reach the secondary pressure before reaching the lowest melt viscosity from the front, and t3−t2 = 0 to 10 minutes.
[0028]
The magnitude of the primary pressure can be set to 0.5 to 1.0 MPa. When the primary pressure is less than 0.5 MPa, voids, scrapes, etc. are likely to occur, and when the primary pressure is greater than 1.0 MPa, molding deviation is likely to occur. Moreover, pressurization with primary pressure can be performed for 5 to 30 minutes, for example.
[0029]
The magnitude of the secondary pressure can be set to 1.5 to 2.5 MPa. When the secondary pressure is less than 1.5 MPa, voids, scrapes, and the like are likely to occur, and when the secondary pressure is greater than 2.5 MPa, molding deviation is likely to occur. Moreover, pressurization with a secondary pressure can be performed for 30 to 125 minutes, for example.
[0030]
Further, if the pressure increase from the primary pressure to the secondary pressure is performed in a time shorter than 20 minutes, molding deviation is likely to occur, and if it is performed in a time longer than 30 minutes, voids, scumming, etc. are likely to occur.
[0031]
Further, as shown by the melt viscosity curve B in FIG. 1, the resin (thermosetting resin composition) of the prepreg 1 is gradually melted with time from immediately after the start of heating and pressing, and the viscosity gradually decreases. Then, it turns so that it hardens gradually at a certain point in time t3, and the viscosity gradually rises again and finally hardens. Therefore, the minimum melt viscosity of the resin (thermosetting resin composition) of the prepreg 1 means the viscosity at the time when the resin (thermosetting resin composition) of the prepreg 1 is melted to become the lowest viscosity. This minimum melt viscosity is measured before heat-press molding of the laminate 15. First, a predetermined amount of resin (thermosetting resin composition) is sampled from the prepreg 1 and placed in a measurement pot. The resin (thermosetting resin composition) in the measurement pot is heated from room temperature to 150 ° C. at a temperature rising rate of 1.5 ° C./min. Then, the melt viscosity of the resin (thermosetting resin composition) in the measurement pot is measured using a solid meter or the like to obtain a melt viscosity curve B as shown in FIG. This is used for heat and pressure molding.
[0032]
Further, if the timing of reaching the secondary pressure from the primary pressure (time point t2 when the secondary pressure is reached) is earlier than 10 minutes before the above-mentioned minimum melt viscosity is reached, molding deviation tends to occur. If it is after the time point when the above-mentioned minimum melt viscosity is reached, voids, blurring and the like are likely to occur.
[0033]
On the other hand, the temperature setting of the pressure plate 16 at the time of heat and pressure molding is shown by the curve D in FIG. 1, and the temperature is increased from the normal temperature at the start of heat and pressure molding to the primary temperature of a certain size. After being performed (D1 range), after being held at this constant primary temperature for a certain period of time (D2 range), after this, the temperature was raised from the primary temperature to the secondary temperature (D3 range). The temperature is changed so as to be performed at this constant secondary temperature (the range of D4) until the end of heating and pressing.
[0034]
Said primary temperature can be set to 100-130 degreeC, and it heats up to primary temperature over 1-15 minutes from normal temperature. The holding time at the primary temperature is 20 to 30 minutes. Furthermore, said secondary temperature can be set to 170-200 degreeC, and is heated up to secondary temperature over 20 to 70 minutes from primary temperature. The holding time at the secondary temperature is 50 minutes or longer (until the end of molding). Furthermore, the change of the temperature (product temperature) of the laminate 15 in the above-described heat and pressure molding is shown by a dashed line curve C in FIG.
[0035]
In the present invention, since the pressure setting is changed as described above in the heat and pressure molding, the secondary pressure is increased immediately before the resin of the prepreg 1 is cured by gradually increasing the pressure during the heat and pressure molding. In addition, by applying to the inner layer material 2 and the outer layer material 3, it is possible to prevent displacement of the inner layer material 2, and to manufacture a multilayer printed wiring board having a highly accurate circuit pattern.
[0036]
In the above-described method for producing a multilayer printed wiring board, it is preferable to put the laminate 15 in a reduced pressure state prior to heat and pressure molding. That is, after the laminate 15 is disposed between the pair of pressure plates 16 and 16, the atmosphere of the laminate 15 is reduced to a reduced pressure state by evacuation without pressing the laminate 15 with the pressure plates 16 and 16. For example, the laminate 15 can be subjected to a reduced pressure treatment by holding the laminate 15 for 30 to 60 minutes in a reduced pressure state of 1.3 to 6.7 kPa (10 to 50 Torr).
[0037]
And by making the laminate 15 in a reduced pressure state prior to heat and pressure molding, generation of molding voids due to the shape of the circuit pattern and moisture absorption of the prepreg 1 can be reduced, and good moldability is ensured. Is something that can be done.
[0038]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
[0039]
Example 1
As the prepreg 1, “R-1661” (FR-4 prepreg, size 510 × 610 mm, thickness 0.1 mm, resin content 52%) manufactured by Matsushita Electric Works Co., Ltd. was used. In addition, as the inner layer material 2, a circuit is formed on a double-sided copper-clad laminate (“R-1766” manufactured by Matsushita Electric Works Co., Ltd., FR-4 core, size 510 × 610 mm, thickness 0.1 mm, copper foil thickness 35 μm). A printed wiring board on which a pattern was formed was used. Further, as the outer layer material 3, a copper foil having a size of 510 × 610 mm and a thickness of 12 μm was used.
[0040]
Then, first, as shown in FIG. 2, after four prepregs 1 and five inner layer materials 2 are alternately stacked, the prepreg 1 is partially welded to the inner layer material 2 with a heater jig 13, and the prepreg The inner layer core material 14 was formed by temporarily fixing 1 and the inner layer material 2. In this welding process, a heater jig 13 using ultrasonic vibration is brought into contact with the surface end portion of the outermost inner layer material 2 with a pressure of 6 kPa, and a part of the prepreg 1 corresponding to the contact portion is 300. The heating was performed at a temperature of 0 ° C., and the size of the welded portion was 3 × 20 mm.
[0041]
After forming the inner layer core material 14 as described above, the prepreg 1 similar to the above is stacked on both surfaces of the inner layer core material 14, and the outer layer material 3 is further stacked on the outer side of the stacked prepreg 1 to form the laminate 15. Formed. Next, as shown in FIG. 3, the laminate 15 is disposed between the pair of pressure plates 16, 16, and the laminate 15 is sandwiched between the pair of pressure plates 16, 16, and is heated and pressed to form a multilayer. A printed wiring board was manufactured.
[0042]
The pressure setting applied to the laminate 15 during the heat and pressure molding was changed as follows. First, a pressure of 0.5 MPa is used as the primary pressure for 20 minutes (A1 range) from the start of heat and pressure molding, and then the pressure is increased from the primary pressure to a secondary pressure of 2.0 MPa over 20 minutes. (Range of A2). At this time, the resin of the prepreg 1 draws a melt viscosity curve as shown by the curve C in FIG. 1, and the time t2 when the secondary pressure is reached is 10 minutes before the time t3 when the resin of the prepreg 1 reaches the minimum melt viscosity. Met. And it shape | molded for 60 minutes with this secondary pressure (the range of A3), and the heat | fever pressurization shaping | molding was complete | finished.
[0043]
Moreover, the temperature setting applied to the laminate 15 at the time of heat and pressure molding was changed as follows. First, after raising the temperature to 130 ° C., which is the primary temperature, over 5 minutes from the start of heat and pressure molding (D1 range), this primary temperature was maintained for 10 minutes (D2 range). Next, the temperature was raised from a primary temperature to a secondary temperature of 180 ° C. over a period of 25 minutes (range D3). And it shape | molded for 80 minutes at this secondary temperature (range of D4), and the heat | fever pressurization shaping | molding was complete | finished. Moreover, the product temperature (temperature of the laminate 15) in such heat-pressure molding was increased from 1 to 3 ° C./min from the start to the end of the heat-pressure molding.
[0044]
(Example 2)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that the laminate 15 was left in a reduced pressure state of 6.7 kPa for 30 minutes and subjected to a reduced pressure treatment prior to heat and pressure molding.
[0045]
(Comparative example)
A multilayer printed wiring board was produced in the same manner as in Example 1 except that the change in pressure applied to the laminate 15 during the heat and pressure molding was different from that in Example 1. That is, first, a pressure of 0.5 MPa was used as the primary pressure for 10 minutes from the start of the heat and pressure molding, and then the pressure was increased from the primary pressure to a secondary pressure of 2.0 MPa over 10 minutes. The time when the secondary pressure was reached was 40 minutes before the time when the resin of the prepreg 1 (thermosetting resin composition) reached the minimum melt viscosity. And it shape | molded for 90 minutes with this secondary pressure, and the heat | fever pressurization shaping | molding was complete | finished.
[0046]
About the multilayer printed wiring board of said Examples 1, 2 and a comparative example, the interlayer shift | offset | difference which arose by heat press molding was measured. For the interlayer displacement, test coupons for layer displacement measurement were arranged in each layer (4 corners of the multilayer printed wiring board), and the amount of displacement of the test coupons at each corner was measured by an X-ray apparatus. Further, as an evaluation of moldability, the presence or absence of molding defects such as voids and scum was visually confirmed. In addition, the above-mentioned evaluation of misalignment and formability was performed with the number of samples n = 20. The results are shown in Table 1.
[0047]
[Table 1]

[0048]
As is clear from Table 1, the interlayer displacement was smaller in Examples 1 and 2 than in the comparative example. In addition, the moldability of Example 1 was higher than that of Example 2.
[0049]
【The invention's effect】
As described above, the invention of claim 1 of the present invention overlaps a plurality of inner layer materials via a prepreg, partially welds the prepreg to the adjacent inner layer material, temporarily fixes the adjacent inner layer materials, After the outer layer material is further laminated on the surface of the outer inner layer material via the prepreg, the inner layer material and the outer layer material are laminated by welding each prepreg to the adjacent inner layer material and outer layer material by heating and pressing. In the manufacturing method of the multilayer printed wiring board to perform, after performing said heat press molding at the primary pressure of 0.5-1.0 MPa from the start of heat press molding, it is secondary of 1.5-2.5 MPa. The pressure is increased from the primary pressure to the secondary pressure over a period of 20 to 30 minutes, and the timing of arrival from the primary pressure to the secondary pressure is increased when the product temperature is 1 to 3 ° C / min. While the prepreg resin reaches the minimum melt viscosity 10 minutes before that time, gradually increase the pressure during the heat and pressure molding so that the secondary pressure is applied to the prepreg, inner layer material and outer layer material immediately before the resin of the prepreg is cured. By doing so, it is possible to prevent the positional deviation of the inner layer material, and to reduce the positional deviation of the circuit pattern formed on the inner layer material, and to manufacture a multilayer printed wiring board having a highly accurate circuit pattern. is there.
[0050]
In the invention of claim 2 of the present invention, since the prepreg, the inner layer material and the outer layer material are put into a reduced pressure state before the heat and pressure molding, the circuit pattern shape of the inner layer material, moisture absorption of the prepreg, etc. Generation of the resulting molding void can be reduced, and good moldability can be ensured.
[Brief description of the drawings]
FIG. 1 is a graph showing an embodiment of the present invention and showing changes in pressure setting, temperature setting, melt viscosity curve, and product temperature.
FIGS. 2A and 2B show the same welding process, wherein FIG. 2A is a schematic side view, and FIG. 2B is a schematic plan view.
FIG. 3 is a schematic side view showing the heating and pressing molding process same as above.
[Explanation of symbols]
1 prepreg
2 Inner layer material
3 Outer layer material

Claims (2)

A plurality of inner layer materials are stacked via a prepreg, the prepreg is partially welded to the adjacent inner layer material, and the adjacent inner layer materials are temporarily fixed together, and the outer layer material is further interposed on the surface of the outermost inner layer material via the prepreg. In the method of manufacturing a multilayer printed wiring board in which the inner layer material and the outer layer material are laminated by welding each prepreg to the adjacent inner layer material and outer layer material by heating and pressing, After pressure molding is performed at a primary pressure of 0.5 to 1.0 MPa from the start of heat and pressure molding, it is performed at a secondary pressure of 1.5 to 2.5 MPa, and the pressure is increased from the primary pressure to the secondary pressure. Is performed over a period of 20 to 30 minutes, and the timing of reaching the primary pressure from the primary pressure is as long as the product temperature is raised at 1 to 3 ° C./minute and the resin of the prepreg is at the minimum melt viscosity. It is between the time of reaching 10 minutes before Method for manufacturing a multilayer printed wiring board characterized by and. The method for producing a multilayer printed wiring board according to claim 1, wherein a prepreg, an inner layer material, and an outer layer material are placed in a reduced pressure state before heat-press molding.

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