JP4003769B2 - Circuit forming substrate manufacturing method and circuit forming substrate manufacturing material - Google Patents

Description

  The present invention relates to a method for manufacturing a circuit-formed substrate used in various electronic devices and a material for manufacturing the circuit-formed substrate.

  As electronic devices have become smaller and more dense in recent years, more and more circuits and components can be integrated on a circuit-forming board on which electronic components are mounted. High-density substrates have been developed (for example, “Surface mount technology” published by Nikkan Kogyo Shimbun, January 1997 issue, Kiyoshi Takagi; “Remarkable development trend of build-up multilayer PWB”).

  The prior art will be described with reference to FIGS. 6 (A) to 6 (G).

  A substrate material 61 shown in FIG. 6A is a prepreg in which a glass fiber woven fabric used for a circuit-forming substrate is impregnated with a thermosetting epoxy resin or the like to be in a B-stage state by a method such as drying. A film 62 is attached to both surfaces of the substrate material 61 by a laminating method using a hot roll or the like.

Next, as shown in FIG. 6B, via holes 63 are formed in the substrate material 61 by a processing method such as laser. Then, as shown in FIG. 6C, conductive holes 64 filled with conductive particles such as copper powder and a thermosetting resin, a curing agent, a solvent, etc. are filled in the via holes 63. Thereafter, when the film 62 is peeled off, the conductive paste 64 protrudes as shown in FIG. When copper foils 65 are arranged on both sides and heated and pressed by a hot press apparatus (not shown), the substrate material 61 is thermally cured as shown in FIG. 6E, and the conductive paste 64 is compressed to be front and back. Copper foil 65 is electrically connected. At that time, the epoxy resin impregnated in the substrate material 61 flows and flows out to form a flow-out portion 66. Thereafter, excess portions of the end portions are cut off to form the shape as shown in FIG. 6F, and the copper foil 65 is processed into a desired pattern by a method such as etching to form a circuit 67, which is shown in FIG. 6G. Such a double-sided circuit forming substrate is obtained.
Kiyoshi Takagi, “Development Trend of Remarkable Build-Up Multilayer PWB” “Surface Mount Technology” January issue, Nikkan Kogyo Shimbun, 1997

  However, in the manufacturing method as described above, electrical connection may be insufficient between the front and back sides of the circuit forming substrate. Further, when the multilayer circuit forming substrate is formed by the above manufacturing method, the same defect may occur in the surface layer and inner layer circuits.

  The main cause is the generation of outflow particles 610 in which conductive particles in the conductive paste 64 flow out of the via holes 63 as shown in FIG. In order to realize an ideal electrical connection, the conductive paste 64 is compressed in the vertical direction of FIG. 6 (E), and the conductive particles in the conductive paste are efficiently brought into firm contact with each other. It is necessary to make a strong contact. However, as can be seen from the formation of the flow-out portion 66 in the process from FIG. 6D to FIG. 6E, the thermosetting resin in the substrate material 61 flows outward. At that time, the conductive particles in the conductive paste 64 are washed away in the lateral direction of FIG. 6E, and as a result, the compression of the conductive paste 64 cannot be realized efficiently, and the electrical connection by the conductive paste 64 is performed. Becomes unstable. In the above description, the case of a substrate material using a glass woven fabric and a thermosetting resin has been described. However, even when inorganic fibers other than glass, organic fibers such as aramid, and non-woven reinforcing materials other than woven fabric are used. It is the same.

  However, when the woven fabric is used, the flow resistance in the woven fabric is particularly small, so that the flow of the thermosetting resin becomes remarkable and it is difficult to electrically connect with the conductive paste. Furthermore, the phenomenon that the fibers constituting the woven fabric are shifted has an adverse effect. The phenomenon will be described with reference to FIGS. As shown in FIG. 7A, a via hole 63 is formed in a substrate material 61 using a glass fiber woven fabric 68 by using a laser. When the portion is viewed from above, the glass fiber woven fabric 68 is cut and the via hole 63 is processed as shown in FIG. Thereafter, the steps described with reference to FIGS. 6C to 6E are performed. When the via hole 63 portion of the circuit forming substrate thereafter is observed, the conductive paste 64 spreads around due to the pressure applied during hot pressing, the flow of the impregnating resin, etc., as shown in FIG. It is moved in the outward direction of the via hole 63 from the original regular arrangement. When such a phenomenon occurs, compression of the conductive paste 64 becomes inefficient. Such a phenomenon is a problem in the manufacture of such a circuit-formed substrate in terms of variation in resistance value of electrical connection and reliability.

  In recent years, since a thin circuit forming substrate has been demanded, a thin material is often used for a glass fiber woven fabric. However, in such materials, the glass fiber filling degree is low and the gaps between the fibers are relatively large, so the above-described problems become significant. In particular, when the thickness of the glass fiber woven fabric is 100 μm or less, the above phenomenon becomes a serious problem.

  The main factors that determine the amount of compression of the conductive paste 64 are the amount by which the substrate material 61 is compressed in the thickness direction in the hot press process in FIGS. 6D to 6E, and FIG. 6D. This is the amount by which the conductive paste 64 protrudes from the substrate material 61. In the high-density circuit forming substrate, the number of points where the layers are connected through the via holes 63 is enormous, so an element that gives a compressive action to the conductive paste 64 is necessary in addition to controlling the two main factors described above.

  In the method for producing a circuit-formed substrate of the present invention, resin flow in the hot press process is limited. Thereby, the electrical connection by interlayer connection parts, such as an electrically conductive paste, is performed efficiently.

  Moreover, in the material for manufacturing the circuit forming substrate of the present invention, a resin whose flow in the hot press process is controlled is used. Thereby, the electrical connection by interlayer connection parts, such as an electrically conductive paste, is performed efficiently.

  As a result, the reliability of the electrical connection between layers using a conductive paste or the like is greatly improved, and a high-density and high-quality circuit forming substrate can be provided.

  In the manufacturing method of the circuit formation board | substrate of this invention, it is set as either of the following structures. A) Restrict resin flow in the hot press process. B) The reinforcing fibers are fused or bonded together. C) Decrease the thickness of the substrate material after the filling step. D) A low fluidized bed is formed with filler mixed in the substrate material. In addition, in the material for manufacturing a circuit-formed board according to the present invention, a volatile component is provided so that a physical property value for controlling resin flow in the hot pressing process is given or the thickness of the board material can be efficiently reduced after the filling process. It is set as the structure containing. According to the present invention, it is possible to efficiently develop an electrical connection by an interlayer connection portion such as a conductive paste.

  In particular, when a woven fabric is used as a reinforcing material for the substrate material, the special effect of stabilizing the connection between layers while taking advantage of the dimensional stability of the woven fabric is exhibited. This is due to processing such as controlling the fluidity or locally preventing the movement of the fibers at the portion where the interlayer connection is performed, or performing processing such as reducing the thickness of the substrate material.

  As a result, the reliability of electrical connection between layers using an interlayer connection portion such as a conductive paste is improved, and a high-quality high-density circuit formation substrate can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to what makes the same structure, and detailed description is abbreviate | omitted.

(Embodiment 1)
FIGS. 1A to 1G are process cross-sectional views illustrating a method for manufacturing a circuit forming substrate and a material for manufacturing the circuit forming substrate in the first embodiment of the present invention.

  As shown in FIG. 1A, first, a film 12 having a thickness of 20 μm is bonded to both surfaces of a substrate material 11 made of a prepreg having a thickness of 100 μm impregnated with a thermosetting epoxy resin using a glass fiber woven fabric as a reinforcing material. Polyethylene terephthalate (PET) is used for the film 12. If necessary, the film 12 may be coated with a thermosetting resin such as an epoxy resin.

  Thereafter, as shown in FIG. 1B, a via hole 13 having a diameter of about 200 μm is processed using a carbon dioxide laser.

  Thereafter, as shown in FIG. 1C, the conductive paste 14 is filled into the via holes 13 by a method such as screen printing. The conductive paste 14 is obtained by kneading copper powder having a diameter of about 5 μm, a thermosetting resin, and a curing agent. A solvent or the like may be added to the conductive paste 14 for the purpose of adjusting the viscosity.

  Next, as shown in FIG. 1D, when the films 12 on both sides of the substrate material 11 are peeled off, the conductive paste 14 protrudes from the substrate material 11 to the thickness of the film 12. Copper foil 15 is arranged on both sides.

  Next, when a hot press step of heating and pressing in the vertical direction in the figure is performed, a shape as shown in FIG. At that time, the thermosetting resin in the substrate material 11 flows and forms a flow-out portion 16.

  Next, as shown in FIG. 1F, the peripheral portion of the substrate material 11 is cut into a desired size. A circuit 17 is formed by patterning the copper foil 15 by a method such as etching to obtain a double-sided circuit forming substrate as shown in FIG.

  The mass of the resin that flows in the vicinity of the substrate material 11 by flowing in the hot press process with respect to the mass of the substrate material 11 before the hot press in the above process, that is, the mass of the flow-out portion 16 in FIG. The ratio is the resin flow rate. In order to solve the problem of insufficient electrical connection by the conductive paste 14 described in the background art, the resin flow rate must be at least 20% or less.

Table 1 shows examples of experimental results examined by the inventor regarding the resin flow rate. Table 1 summarizes the following measurement results.
1) Substrate material thickness before and after the hot press process 2) Amount of resin flow calculated from the weight of the flow-out part generated in the peripheral part in the hot press process and the substrate material weight before the hot press process 3) 500 via holes on the front and back of the substrate Via connection resistance value (average value) per location obtained from the electrical resistance value of a test pattern circuit that forms a series circuit with copper foil
In the sample of Experiment No. 1, the resin flow rate is 22.8%, the via connection resistance varies from several Ω to several hundred Ω, and there are also vias without electrical connection.

  Moreover, when the cross section of a via part is observed about the sample of experiment number 1, the electrically-conductive particle in the electrically conductive paste 14 has flowed out.

  However, in the samples of Experiment Nos. 2 to 7 in which the conditions of the hot press were studied so as to reduce the resin flow rate, the via connection resistance value decreased, and a practical via was controlled by controlling the resin flow rate to 20% or less. Connection resistance value is obtained.

  In addition, even when the reliability of the sample is stored in high temperature and high humidity for a long period of time and the change in via connection resistance with time is measured, the resin flow rate of 20% or less shows good characteristics.

  Further, as is apparent from the results of Table 1, an initial via connection resistance value can be obtained with a resin flow amount of 10% or less. In this case, better results can be obtained with regard to reliability.

  In order to improve electrical connection, it is effective to keep the resin flow rate lower. On the other hand, as can be seen from the result of Experiment No. 7, it is 1 to mold the substrate material 11 well in the hot press process. % Resin flow is required. In Table 1, the following phenomenon is described as poor fillability. The substrate of Experiment No. 7 after the hot pressing step has a portion that looks white, and when enlarged, a portion where the bubbles and the surface of the substrate material are uneven is observed. This is a failure mode called whitening phenomenon in the production of printed wiring boards and the like because the resin flow is small and the irregularities of the inner layer circuit are not filled and bubbles and irregularities are generated. When whitening occurs, characteristics such as the peel strength of the copper foil and solder heat resistance deteriorate.

  As a means for achieving the above resin flow rate of 20% or less, it is effective to control the rate of temperature rise to 3 ° C. or less per minute in the temperature profile in the hot press process.

  However, considering the fact that the time required for the hot pressing process is very long, or the temperature rise rate is lowered too much to adversely affect the moldability of the resin, the temperature rise rate should be 0.5 ° C. or more per minute. It is preferable to do.

  Further, in consideration of the viscosity change during heating of the resin or the like contained in the substrate material 11, the temperature rising rate is controlled to 3 ° C./min or less only in the time zone in which the fluidity is increased in the hot press process. In the time zone, the temperature may be increased at a faster rate.

  It is also possible to obtain the above effect by controlling the characteristics of the substrate material 11. For this purpose, the uncured epoxy resin is heated and dried, and the curing time is changed by controlling the volatile components, the amount of residual solvent, and the degree of thermosetting by the heating temperature and time. By such a method, the curing time representing the characteristics of melting and curing of the substrate material during hot pressing is set to 110 seconds or less. By using a substrate material containing such a resin material, the amount of resin flow can be reduced to 20% or less, and electrical connection between layers using a conductive paste can be improved.

  In addition, in order to avoid generation | occurrence | production of the embedding defect mentioned above, it is preferable that hardening time shall be 10 second or more. Furthermore, from the viewpoint of absorbing the adhesiveness between the copper foil 15 and the substrate material 11 shown in FIG.

(Embodiment 2)
Although Embodiment 1 is an example of a double-sided circuit formation substrate, it is preferable to apply the present invention also when manufacturing a multilayer circuit formation substrate as shown in FIGS. 2 (A) to 2 (E).

  First, a double-sided circuit forming substrate as shown in FIG. Next, as shown in FIG. 2 (B), the substrate material 11 filled with the conductive paste 14 and the copper foil 15 are arranged in alignment with the front and back of the double-sided circuit-formed substrate, and heated and pressed by a hot press device or the like. Thus, the substrate material 11 is molded and cured as shown in FIG. At that time, the flowing component of the substrate material 11 forms the flow-out portion 26.

  In such a process, the weight of the flow-out portion 26 (resin flow amount) is set to 20% or less with respect to the weight of the two substrate materials 11 by the method described in the first embodiment.

  Next, after cutting off an excess part of the periphery to obtain a shape as shown in FIG. 2D, the copper foil 15 is patterned by a method such as etching to form a circuit 27, and FIG. A four-layer circuit forming substrate as shown in FIG.

  Also in the manufacture of such a multilayer circuit forming substrate, the electrical connection between the layers can be satisfactorily formed by applying the manufacturing method and manufacturing material of the circuit forming substrate of the present invention.

  Note that a resin flow amount of 1% or more is required to embed circuit irregularities of the inner layer circuit formation substrate when manufacturing the multilayer circuit formation substrate. When the resin flow rate is controlled to 20% or less by controlling the curing time of the resin contained in the substrate material 11, the curing time is preferably 50 seconds or more and 110 seconds or less considering the embedding property of the inner layer circuit. .

  Note that the double-sided circuit formation substrate used in the present embodiment may be the one described in the first embodiment or a substrate in which interlayer connection is formed by a normal plating method or the like. Further, the substrate material 11 may be temporarily bonded to the double-sided circuit formation substrate in the step shown in FIG.

(Embodiment 3)
A third embodiment of the present invention will be described below with reference to FIGS. 3 (A) to 3 (C).

  As shown in FIG. 3A, via holes 13 are formed in a prepreg substrate material 11 using a glass fiber woven fabric 38 using a laser.

  When the portion is viewed from above, the glass fiber woven fabric 38 is cut and the via hole 13 is processed as shown in FIG. At this time, a welded portion 39 as shown in FIG. 3B is formed by a specific processing method.

  When the via hole 13 is filled with the conductive paste 14 after the welded portion 39 is formed and a hot pressing process is performed, the conductive paste 14 spreads around the via hole 13 as shown in FIG. Is prevented. Therefore, the electrical interlayer connection by the conductive paste 14 is good.

  When the via hole 13 is formed by drilling, the welded portion 39 is solidified by changing the resin component in the substrate material 11 by frictional heat at the time of processing and solidifying the glass fiber woven fabric 38 around the via hole 13. It can also be realized by fixing with. Thus, the welded portion 39 does not need to be composed only of a reinforcing material such as glass fiber, and the resin component or the like in the substrate material 11 is hardened or denatured by heat at the time of processing or the like in the subsequent hot press process. The same effect can be obtained if the fluidity is lost. However, when the via hole 13 is formed using a laser, it is preferable to form the welded portion 39 mainly composed of the glass fiber woven fabric 38 by melting or modifying the glass fiber woven fabric 38.

  Table 2 shows an example of the inventor's examination results.

  The via hole 13 is processed under various conditions using three types of laser oscillators to produce a double-sided circuit-formed substrate, and the results of comparing the via connection resistance values as described in the first embodiment are summarized. Yes.

  As can be seen from this result, the via connection resistance value is related to the wavelength of the laser. When the substrate material in which the via hole 13 is processed is observed in detail, formation of a welded portion is confirmed at an oscillation wavelength of 10.6 μm, but no welded portion is confirmed when an oscillation wavelength of 9.4 μm is used.

  When using various lasers such as excimer laser, YAG harmonic, carbon dioxide laser, etc., the welded part can be formed depending on the processing conditions, but carbon dioxide laser heating is more effective than ablation without heating such as excimer laser. It is preferable for forming the welded portion.

  Furthermore, as described above, using a laser having a wavelength of 10 μm or more is efficient in forming the welded portion 39. In practical use, the use of a carbon dioxide laser is advantageous in terms of processing speed and cost. In addition, A) processing efficiency, oscillation efficiency, B) generated laser beam includes a plurality of oscillation wavelengths, and C) laser in the range of 10 to 11 μm from the viewpoint of application to fine processing, that is, light condensing by an optical system. A processing method mainly composed of is more preferable.

(Embodiment 4)
Embodiment 4 will be described with reference to FIGS. 4 (A) to 4 (H).

  As shown in FIG. 4A, the substrate material 41 is a prepreg having a thickness of 100 μm in which a glass fiber woven fabric is used as a reinforcing material and a film 12 having a thickness of 20 μm made of polyethylene terephthalate (PET) is bonded to both sides. If necessary, the film 12 may be coated with a thermosetting resin such as an epoxy resin. Unlike the substrate material 11 in the first embodiment, the substrate material 41 leaves a large amount of volatile components remaining when the prepreg is manufactured. From the weight change before and after drying at 160 ° C. for 1 hour, the volatile content is 3%.

  Subsequent steps shown in FIGS. 4B to 4D are the same as those in the first embodiment.

  Next, the substrate material 41 is introduced into a vacuum drying apparatus (not shown) and dried in a vacuum of about 133 Pa for 1 hour. During the drying, in order to prevent the temperature of the substrate material 41 from decreasing, hot air of 50 ° C. is introduced into the vacuum drying apparatus and the pressure is reduced again three times. In this step, as shown in FIG. 4E, the thickness of the substrate material 41 is reduced, and the reduction amount is about 2 μm. As a result, before drying, the height of the protruding portion of the conductive paste 14 from the substrate material 41 of about 20 μm increases by about 1 μm on the front and back sides of the substrate material to about 22 μm.

  Next, as shown in FIG. 4 (F), the copper foil 15 is disposed on both surfaces of the substrate material 41, and a hot pressing process is performed in which heat and pressure are applied in the vertical direction in the figure. The shape is as shown.

  Further, the copper foil 15 is patterned by a method such as etching to form a circuit 17 to obtain a double-sided circuit forming substrate as shown in FIG.

  When the circuit forming substrate is manufactured through the above-described steps, the height of the protruding portion of the conductive paste 14 is increased before the hot pressing, although it is only 2 μm. Make the connection good.

  Since a normal hot press process uses a vacuum press, it is considered that most of the volatile components in the substrate material are removed during the hot press process. In such a manufacturing method, the amount of the component of the substrate material that flows during the hot pressing process is relatively large, which is disadvantageous for compressing the conductive paste in the thickness direction of the substrate to develop an electrical connection.

  In the present embodiment, the volatile components in the substrate material 41 are removed by vacuum drying before the hot pressing step, and the flow during hot pressing is controlled. Further, removal of volatile components increases the protruding height of the conductive paste 14 from the substrate material 41, thereby increasing the effective compression amount. As a result, the compression of the conductive paste 14 in the hot press process becomes extremely efficient, and the electrical connection between the circuits 17 on the front and back of the circuit forming substrate becomes sufficient.

  The method described above is also suitable for application to the substrate material 11 when manufacturing a multilayer circuit forming substrate as described in the second embodiment.

  The effect of the present embodiment is remarkable when the volatile content of the substrate material 41 is 0.5% or more from the results of the experiment. However, if the volatile content is too large, the storage stability of the substrate material 41 may decrease. Yes, preferably 5% or less.

  Moreover, it is preferable to contain a high boiling point solvent such as BCA (butyl carbitol acetate) in the production process of the substrate material 41 as a volatile component.

  Although the process of reducing the thickness of the substrate material 41 has been described using a vacuum drying method, it may be performed by a normal drying method that involves heating under conditions that do not cause a problem with the physical properties of the substrate material 41.

  In addition, in the process of reducing the thickness of the substrate material, the amount of protrusion of the interlayer connection portion from the substrate material can be reduced even if the substrate material is selectively etched by a dry or wet etching method using plasma or excimer laser. It can be secured. In this case, there is an effect that the thickness reduction amount of the substrate material is stabilized.

(Embodiment 5)
A fifth embodiment of the present invention will be described below with reference to FIGS. 5 (A) to 5 (C).

  As shown in FIG. 5A, via holes 13 are formed in a prepreg substrate material 51 using a glass fiber woven fabric 38 using a laser. The substrate material 51 includes a filler 510 as a solid content.

A normal substrate material is a glass fiber woven fabric 38 impregnated with a liquid material called a varnish obtained by diluting a thermosetting resin with a solvent or the like, and then volatilizing a volatile component such as a solvent or the like in a drying process to increase the degree of curing of the thermosetting resin. Manufactured by adjusting method. A substrate material 51 used in the present embodiment is manufactured by dispersing filler in the varnish. In the present embodiment, a silica-based filler using silica (SiO ₂ ) having a diameter of about 1 to ₂ μm is used.

  As shown in FIG. 5A, a low fluidized bed 511 is formed around the via hole 13. The low fluidized layer 511 is a layer in which processing energy is absorbed by the filler 510 and converted into heat during laser processing, and the surrounding thermosetting resin is denatured, and the denatured thermosetting resin is a layer having the filler 510 as a solid as a core. It is formed by the phenomenon etc. which become. The formation efficiency is much higher than that without the filler 510. The low fluidized bed 511 may naturally include the glass fiber woven fabric 38 as a component.

  After the low fluidized bed 511 is formed, when the via hole 13 is filled with the conductive paste 14 and the hot press process is performed, as shown in FIG. The spread of is prevented. Therefore, the electrical interlayer connection by the conductive paste 14 is good.

  The formation of the low fluidized bed 511 can also be realized by solidifying together with the filler 510 by changing the resin component or the like in the substrate material 51 by frictional heat or the like when the via hole 13 is formed by drilling. However, when forming the via hole 13 using a laser, it is preferable that the filler 510 absorb energy and convert it into heat to form the low fluidized bed 511.

  Regarding the wavelength of the laser used in this step, the formation of the low fluidized bed 511 is efficient when an oscillation wavelength of 9 μm or more is used with a carbon dioxide gas laser. Further, a material other than silica may be used as the material of the filler 510, and the same effect can be obtained by using talc, gypsum powder, or a metal hydroxide (aluminum hydroxide, etc.).

  In all the embodiments described above, the substrate material is described as a glass fiber woven fabric impregnated with a thermosetting resin to form a B-stage, but a nonwoven fabric may be used instead of the glass fiber woven fabric. Organic fibers such as aramid may be used instead of glass fibers.

  In the first, second, and fourth aspects of the invention, a B stage film may be used instead of the prepreg as the substrate material.

  Further, a material in which a woven fabric and a nonwoven fabric are mixed, for example, a material in which a glass fiber nonwoven fabric is sandwiched between two glass fibers, may be used as the reinforcing material.

  Moreover, although the thermosetting resin in all the embodiments of the present invention has been described as an epoxy resin, the following may be used. Epoxy / melamine resins, unsaturated polyester resins, phenol resins, polyimide resins, cyanate resins, cyanate ester resins, naphthalene resins, urea resins, amino resins, alkyd resins, silicon resins, Furan resin, polyurethane resin, amino alkyd resin, acrylic resin, fluorine resin, polyphenylene ether resin, cyanate ester resin, etc., or a mixture of two or more thermosetting resin compositions or thermoplastic resins It is also possible to add a thermosetting resin composition modified with, and if necessary, a flame retardant or an inorganic filler.

  Further, a circuit made of metal foil or the like temporarily fixed to a support can be used instead of copper foil.

  Moreover, it demonstrated using the electrically conductive paste which knead | mixed electrically conductive particles, such as copper powder, a hardening | curing agent, and a thermosetting resin as an interlayer connection part. Instead, various compositions such as a kneaded polymer material having an appropriate viscosity and conductive particles that are discharged into the substrate material at the time of hot pressing, or a solvent added may be used. Furthermore, post-shaped conductive protrusions formed by plating or the like other than the conductive paste, or conductive particles having a relatively large particle size that are not made into a paste can be used alone as an interlayer connection portion.

(A)-(G) is process sectional drawing which shows the manufacturing method of the circuit formation board | substrate of the 1st Embodiment of this invention. (A)-(E) is process sectional drawing which shows the manufacturing method of the circuit formation board | substrate of the 2nd Embodiment of this invention. (A) is a cross-sectional schematic diagram of the via formation process in the manufacturing method of the circuit formation board | substrate of the 3rd Embodiment of this invention, (B) is in the manufacturing method of the circuit formation board | substrate of the 3rd Embodiment of this invention. Via portion top view before filling with conductive paste, (C) is a via portion top view after filling with conductive paste in the circuit forming substrate manufacturing method of the third embodiment of the present invention. (A)-(H) is process sectional drawing which shows the manufacturing method of the circuit formation board | substrate of the 4th Embodiment of this invention. (A) is a cross-sectional schematic diagram of the via | veer formation process in the manufacturing method of the circuit formation board | substrate of the 5th Embodiment of this invention, (B) is in the manufacturing method of the circuit formation board | substrate of the 5th Embodiment of this invention. Via portion top view before filling with conductive paste, (C) is a via portion top view after filling with conductive paste in the circuit forming substrate manufacturing method of the fifth embodiment of the present invention. (A)-(G) is process sectional drawing which shows the manufacturing method of the circuit formation board in a prior art. (A) is a schematic cross-sectional view of a via formation step in a conventional method for manufacturing a circuit-formed substrate, (B) is a top view of a via portion before filling with a conductive paste in a conventional method for manufacturing a circuit-formed substrate, (C). Is a top view of a via portion after filling with a conductive paste in a conventional method of manufacturing a circuit forming substrate

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Substrate material 12 Film 13 Via hole 14 Conductive paste 15 Copper foil 16, 26 Flow-out part 17, 27 Circuit 38 Glass fiber woven fabric 39 Welded part 41 Substrate material 51 Substrate material 510 Filler 511 Low fluidized layer 61 Substrate material 62 Film 63 Via hole 64 Conductive paste 65 Copper foil 66 Outflow portion 67 Circuit 68 Glass fiber woven fabric 610 Outflow particle

Claims (2)

(1) Metal foil or metal foil affixed to a support or metal foil affixed to a support and formed with a circuit pattern (2) B stage state substrate material provided with interlayer connection means (3) Circuit or metal B stage state substrate material with foil and interlayer connection means (4) C stage state substrate material with circuit or metal foil,
A laminating step of laminating at least one together with a B-stage state substrate material provided with an interlayer connection means;
A heat pressing step involving heating and pressurization in the laminating step,
The B stage state substrate material consists of a glass fiber woven fabric, a thermosetting resin, and a filler as a solid content,
The formation of the interlayer connection portion includes a hole forming step for forming a via hole in the B stage state substrate material by laser processing having a specific wavelength, and a filling step for filling the via hole with a conductive substance,
In the hole forming step, the laser processing energy is absorbed by the filler in the B-stage state substrate material and converted into heat, thereby modifying the thermosetting resin,
Forming a low fluidized layer formed by the filler as a core and the modified thermosetting resin as a layer around a via hole,
The method of manufacturing a circuit forming substrate, wherein the low fluidized layer restricts the flow of the thermosetting resin impregnated in the glass fiber woven fabric during heating and pressurizing in the laminating step . The method of manufacturing a circuit forming substrate according to claim 1, wherein the laser processing is performed with a carbon dioxide gas laser having an oscillation wavelength of 9 μm or more.

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