JP2004172646A - Method for manufacturing circuit-formed substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a circuit forming substrate having high density and high reliability by preventing diffusion of a conductive paste or the like.
In the manufacture of a circuit forming substrate, a deteriorated layer 16 is formed on the inner wall of a hole when a through hole 15 or a non-through hole 26 for connecting screens or circuits formed in multiple layers to each other is formed. The action of the altered layer prevents the conductive paste from diffusing around the hole, realizing high-quality hole processing without losing the high speed and economy of energy beam processing, and forming a high-density and highly reliable circuit A substrate can be provided.
[Selection] Figure 1

Description

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

  As electronic devices have become smaller and higher in density in recent years, the adoption of double-sided and multi-layer boards for circuit-forming boards on which electronic components are mounted has increased from the conventional single-sided board, and more circuits can be integrated on the board. Density circuit forming substrates are being developed.

  For high-density circuit-formed substrates, a processing method using an energy beam such as a laser that enables finer processing at higher speeds instead of drilling holes (through holes) that have been widely used in the past. (Surface mounting technology published by Nikkan Kogyo Shimbun, Jan. 1997, written by Kiyoshi Takagi; see "Development Trends of Remarkable Build-Up Multilayer PWB").

  In general, in a hole drilling process using a laser, a hole to be processed is locally heated and sublimated by a laser to form a hole, so that the inner wall of the hole tends to be a rough surface with severe irregularities. Moreover, when the carbide of the material to be processed remains in the hole, it becomes an obstacle when forming connection means such as plating in the hole. To solve this problem, a processing method is adopted in which the peak energy value of the energy beam irradiated to the workpiece is increased and the irradiation time is shortened as much as possible to instantly evaporate and sublimate the workpiece so that there is no thermal effect around the processing area. Has been.

  FIG. 15 shows a cross section of the processed portion when the processing method as described above is performed. FIG. 15A shows an example of processing into a B-stage thermosetting resin film containing an uncured portion, and FIG. 15B shows a nonwoven fabric of an aromatic polyamide (hereinafter referred to as aramid) fiber 3 and a thermosetting resin 2. It is an example of processing in the composite material. In FIG. 15 (a), the inner wall of the processed through hole 4 is made of a thermosetting resin film that is hardly affected by heat. In FIG. 15 (b), the cut surface of the aramid fiber 3 remains as it is. It shows properties that appear on the inner wall. When the substrate material 1 is a porous material having a hole portion 1a, the hole portion 1a may appear on the inner wall of the through hole 4.

  However, as described above, the purpose of drilling holes in the board material is to connect the circuits formed on the front and back of the board or the inner layer to each other. Is formed.

  The through-hole 4 formed in the B-stage resin film is filled with the conductive paste 6 containing the conductive particles 5 by using a printing method or the like, and the copper foil 7 is placed on the front and back of the film and heated and pressed to form the B-stage. FIG. 16A shows a double-sided circuit-formed substrate on which a circuit is formed by patterning the copper foil 7 after the resin is molded and cured. As shown in the figure, the conductive particles 5 in the conductive paste 6 are diffused in the vicinity of the through holes 4 due to the flow of the resin during molding and curing.

  When the same process is performed on the substrate material 1 having the hole 1a shown in FIG. 15B, the conductive particles 5 diffuse around the through-hole 4 as shown in FIG. 16B. At the same time, the conductive particles 5 flow into and diffuse into the hole 1a that appears on the inner wall of the hole. When it is necessary to compress the substrate material 1 in the thickness direction at the time of heating and pressing, a so-called porous substrate material having such a hole portion 1a is often used, but generally the formation of the hole portion 1a is difficult to control. Therefore, the shape is not necessarily stable as shown in FIG. 16B, and the size actually shows considerable variation. At that time, when a large hole portion 1a exists in the vicinity of the through hole 4, the inflow and diffusion of the conductive particles 5 reach a considerably wide range.

  In addition, when the plating 8 is applied after drilling the composite material of the aramid fiber 3 and the thermosetting resin 2, the adhesion between the aramid fiber 3 and the thermosetting resin 2 is insufficient. FIG. 17 shows an example in which the plating solution soak 9 occurs at the interface from the inner wall of the hole when there is an extra portion.

  Since the size of the through holes and connection means is very small on a high-density circuit forming substrate, diffusion of the connection means around the through holes ensures insulation resistance between adjacent connection means or between circuits. It is a serious problem.

  Further, when the conductive paste 6 is compressed in the thickness direction of the substrate material 1 at the time of heating and pressurizing to make the contact between the conductive particles 5 dense to obtain a low-resistance connection means, the conductive property as described above is used. When the conductive particles 5 are diffused, the conductive paste 6 is not sufficiently compressed, which may cause a problem in connection reliability.

  It is an object of the present invention to provide a method for manufacturing a high-density and highly reliable circuit forming substrate that realizes high-quality hole processing without losing the high speed of energy beam processing.

  In order to solve the above problems, the present invention provides a step of preparing a plate-like or sheet-like substrate material composed of a single material or a plurality of materials, and a through-hole or non-through-hole having a desired hole diameter in the substrate material. A hole forming step of irradiating an energy beam under the condition that the diffusion preventing means remains on the inner wall of the hole at the same time, and a step of forming a connecting means with a conductive material in the hole where the diffusion preventing means remains It is a manufacturing method of a circuit formation board.

  The present invention also includes a step of irradiating an energy beam to a plate-like or sheet-like substrate material composed of a single material or a plurality of materials to form a through or non-through hole, and a connecting means using a conductive paste in the hole. And forming a diffusion preventing means formed of the substrate material and a material that reacts with the thermosetting resin in the conductive paste in the vicinity of the inner wall of the hole. .

  According to the present invention, it is possible to prevent the connection means from diffusing around the hole due to the action of the diffusion preventing means, realizing high-quality hole processing without losing the high speed and economy of energy beam processing, and the like. It is possible to provide a circuit forming substrate with high density and reliability.

  As described above, according to the method for manufacturing a circuit forming substrate of the present invention, the diffusion preventing means such as the altered layer or the resin layer is formed on the inner wall of the through or non-penetrating hole. Does not diffuse, and has an effect of improving reliability especially in a high-density circuit formation substrate.

  According to the first aspect of the present invention, there is provided a step of preparing a plate-like or sheet-like substrate material composed of a single material or a plurality of materials, and processing a through-hole or a non-through-hole having a desired hole diameter in the substrate material. At the same time, a circuit forming process is provided that includes a hole forming step of irradiating an energy beam under the condition that the diffusion preventing means remains on the inner wall of the hole, and a step of forming a connecting means with a conductive material in the hole where the diffusion preventing means remains. This is a method for manufacturing a substrate, and has an effect that the connection means does not diffuse around the through or non-through hole by the diffusion preventing means.

  According to the second aspect of the present invention, the irradiation condition of the energy beam is such that the substrate material melts and re-solidifies so that the altered layer as a film-like diffusion preventing means covers a part or the entire inner wall of the hole. The circuit forming substrate manufacturing method according to claim 1, which is a condition for forming, and has a function of forming a dense altered layer.

  The invention according to claim 3 is the method for manufacturing a circuit-formed substrate according to claim 2, wherein the energy beam is a laser beam, has good light-condensing property on the substrate material, and uses an optical element or the like. And has an effect of being easily scanned.

  According to a fourth aspect of the present invention, the laser beam is a carbon dioxide laser, and the method for producing a circuit forming substrate according to the third aspect is such that a high energy beam is obtained and the cost is low. Have.

  In the fifth aspect of the invention, the irradiation condition of the energy beam is the energy amount of the energy beam, and the amount of energy necessary for processing a desired hole size and the altered layer formed on the inner wall of the hole are carbonized. 3. The condition according to claim 2, wherein the amount of energy is not less than the sum of the amount of energy necessary to remain without being reduced, and the amount of energy is less than the amount of energy at which a carbide layer is formed on the inner wall of the hole or the uneven shape is generated on the inner wall of the hole. This is a circuit board manufacturing method that prevents the generation of factors that adversely affect the reliability of connecting means such as carbide layers and uneven shapes on the inner wall of the hole, and stably changes the quality while ensuring the desired hole dimensions. The layer can be formed on the inner wall of the hole.

  The invention according to claim 6 is the circuit forming substrate according to claim 1, wherein the irradiation condition of the energy beam is a condition in which the energy beam diameter on the substrate material is set to 30 to 90% of a desired hole diameter. In addition to removing the portion of the substrate material corresponding to the energy beam diameter, the removal process due to the thermal effect is sequentially propagated to the periphery of the removal processing part, and the thermal effect is necessary for the removal process. This has the effect of stably realizing a series of processes in which a deteriorated layer is formed in a portion that is below the condition, that is, in the vicinity of the inner wall of the hole.

  In the invention according to claim 7, the irradiation condition of the energy beam is such that the diameter of the through or non-through hole to be processed is 110 to 300% of the diameter of the energy beam (spot diameter) irradiated onto the substrate material. The circuit forming substrate manufacturing method according to claim 1, which is a condition set to reach the irradiation time, and has an effect of stably generating a deteriorated layer on the inner wall of the hole.

  According to an eighth aspect of the present invention, the irradiation condition of the energy beam is a condition in which the pulse width of the energy beam irradiated onto the substrate material is set within a range of 50 μs to 1 ms as a half width. The circuit-forming substrate manufacturing method of the present invention has the effect that the temperature near the inner wall of the hole can be easily generated by the altered layer. Preferably, the pulse width is set to a range of 150 μs to 1 ms at a half width. Thus, the formation of a deteriorated layer becomes more effective.

  According to the ninth aspect of the present invention, the irradiation condition of the energy beam is to set the irradiation intensity with respect to the irradiation time axis. The half-value width time with respect to the peak value of the intensity is t1, and the peak value e 2. The condition according to claim 1, wherein t2 is set to be 50% or more and less than 200% of t1, where t2 is a time when the strength falls to 1/2 of the square of (approximately 13.5%). This is a method for manufacturing a circuit-forming board, and brings about a temperature condition near the inner wall of the hole where a deteriorated layer that can not be obtained by a steep fall is generated, and a temperature condition that produces carbide that can be obtained by a slow fall. Has the effect of not being brought about near the inner wall of the hole.

  According to the tenth aspect of the present invention, the irradiation condition of the energy beam is to set the irradiation intensity with respect to the irradiation time axis, and the intensity is from the peak value to the square of the peak value e (about 13.5). %) Is a condition set in a range of 20 μs or more and 1 ms or less. The method for manufacturing a circuit-formed substrate according to claim 1, wherein a sufficient amount of the altered layer is provided on the inner wall of the hole It has the effect that the drilling conditions which can produce | generate and can prevent the production | generation of a carbide | carbonized_material are obtained.

  In the invention according to claim 11, the irradiation condition of the energy beam is a condition for cutting the energy beam bundle up to 98% from the periphery of the energy beam bundle derived from the energy beam oscillator. 1 is a method for manufacturing a circuit-formed substrate according to claim 1, wherein a low-quality beam at the outer peripheral portion of the energy beam is blocked so as not to reach the substrate material, and the energy amount in the cross section of the normal energy beam is from the center to the outer peripheral direction. By using this decrease, the temperature distribution in the hole processing part of the substrate material during hole processing is inclined from the vicinity of the hole center to the outer periphery of the hole, and the altered layer generates the temperature near the inner wall of the hole. It has the effect of making it easy to condition.

  The invention according to claim 12 is the circuit according to claim 1, wherein the irradiation condition of the energy beam is a condition in which the peak energy of the energy beam pulse derived from the energy beam generator is set to 100 W or more and 3000 W or less. This is a manufacturing method of the formation substrate, and when the energy beam is irradiated onto the substrate material, the substrate material instantaneously evaporates and sublimates, and the processing ends without affecting the periphery of the hole. This has the effect of preventing the temperature in the vicinity of the inner wall of the hole from being changed to a condition where the altered layer is likely to be generated.

  According to a thirteenth aspect of the present invention, a plate-like or sheet-like substrate material made of a single material or a plurality of materials is irradiated with an energy beam to form a penetrating or non-penetrating hole, and a conductive material is formed in the hole. The connecting means is formed by a paste (a material that reacts with a thermosetting resin is added), and at the same time, the substrate material and a material that reacts with the thermosetting resin in the conductive paste are formed near the inner wall of the hole. A method of manufacturing a circuit-formed substrate comprising a step of forming a diffusion preventing means (cured layer), which reacts with the thermosetting resin in the substrate material and the thermosetting resin contained in the conductive paste. The diffusion preventing means (cured layer) can be efficiently formed simultaneously with the material (curing agent with high activation) by filling the conductive paste.

  Due to the presence of the diffusion preventing means formed by this manufacturing method, the conductive particles in the paste filled in the through-holes can be used in the subsequent process, for example, when the copper foil is placed on the front and back of the B-stage resin film and heated and pressed. It is possible to prevent diffusion in the vicinity and to manufacture and provide a highly reliable circuit forming substrate.

  According to a fourteenth aspect of the present invention, there is provided the circuit forming substrate manufacturing method according to the twelfth or thirteenth aspect, wherein the conductive material is a paste containing conductive particles. It has an action that can be prevented.

  The invention according to claim 15 is the method for producing a circuit-forming substrate according to claim 14, wherein the conductive particles are selected from those having a particle diameter that is difficult to pass through the diffusion preventing means. It has the effect of preventing diffusion around the hole.

  According to a sixteenth aspect of the present invention, in the step of forming the connecting means, the metal foil is disposed on one or both sides of the substrate material filled with the paste containing conductive particles, and the substrate material is disposed on one or both surfaces. The method for manufacturing a circuit-formed substrate according to claim 14, which has a procedure for compressing by heating and pressing, and has an action of preventing diffusion of paste around the hole during heating and pressing.

  The invention described in claim 17 is characterized in that when the paste used for filling is compressed by heating and pressing, the amount of components other than the conductive particles discharged to the outside of the diffusion preventing means is larger than that of the conductive particles. The method for manufacturing a circuit-formed substrate according to claim 16, wherein the paste is a paste, and the probability that the conductive particles contact each other in the hole is increased, and the electrical connection between the front and back of the substrate material and the inner layer is made highly reliable. In addition, since the degree of freedom of the content ratio of the conductive particles in the paste before filling is expanded, the paste composition having excellent filling properties into fine holes can be employed.

  The invention described in claim 18 is the method for manufacturing a circuit forming substrate according to claim 1 or 13, wherein the conductive material is metal plating, and the plating solution or the metal plated by the diffusion preventing means. Has the effect of preventing diffusion around the hole.

  The invention according to claim 19 is a method for manufacturing a circuit-formed substrate according to claim 1 or 13, wherein at least a portion of the substrate material that forms holes is a resin film containing an uncured portion. When the connection means is formed with a conductive paste or the like, the connection means can be prevented from diffusing around the hole.

  The invention according to claim 20 is the method for producing a circuit-formed substrate according to claim 1 or 13, wherein the substrate material is a composite material of a woven fabric or a non-woven fabric and a resin. While used, the connection means does not diffuse outside the diffusion prevention means.

  The invention according to claim 21 is the method of manufacturing a circuit forming substrate according to claim 19 or 20, wherein the resin is thermosetting, and the formation of diffusion preventing means by energy beam irradiation is easy, and the resin It has the effect of improving reliability such as moisture resistance.

  The invention according to claim 22 is the method for producing a circuit-formed substrate according to claim 21, wherein the resin is in a B-stage state including an uncured component, and a procedure for compressing the substrate material by heating and pressing is provided. It can be used in the connecting means forming step, and also has the effect of preventing diffusion of the connecting means around the hole.

  The invention described in claim 23 is the method of manufacturing a circuit forming substrate according to claim 20, wherein an organic fiber material is used for the woven or non-woven fabric, and the organic fiber having relatively close physical properties to the resin is used. This has the effect that the formation of the altered layer is facilitated.

  The invention as set forth in claim 24 is the method for producing a circuit-formed substrate according to claim 23, wherein aromatic polyamide fibers are mainly used as the organic fiber material, and it is easy to form an altered layer by an energy beam. The circuit forming substrate has actions such as weight reduction and high reliability.

  The invention according to claim 25 is the method for producing a circuit-formed substrate according to claim 23, wherein the heat shrinkage start temperature of the organic fiber material is 150 ° C. or more and less than 300 ° C., and is obtained by irradiation with a laser beam or the like. The organic fiber material has an action capable of forming a dense deteriorated layer by thermally shrinking and melting the organic fiber material due to a temperature rise during heat processing.

  The invention according to claim 26 is the circuit according to claim 13, wherein the diffusion preventing means formed on the inner wall of the hole, or a part thereof, is a deteriorated layer mainly composed of a component in which a woven fabric or a non-woven fabric is melted or the like. This is a method for producing a formation substrate, and has a function that a part or most of a woven fabric or non-woven fabric is integrated at the time of melting to form a dense altered layer.

  The invention according to claim 27 is the diffusion preventing means formed on the inner wall of the hole, or a part thereof, wherein the component in which the woven or non-woven fabric is altered by melting and the part in which the resin is altered are integrated. It is the manufacturing method of the circuit formation board | substrate of description, A denser altered layer can be formed.

  The invention according to claim 28 is the method for manufacturing a circuit-formed substrate according to claim 13, wherein the substrate material is porous, and is easily compressed by heat and pressure, but diffusion of the connecting means occurs. Even in the case of a porous substrate material that is easily deformed, the formation of a deteriorated layer has an effect of preventing diffusion.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
1A to 1F are process cross-sectional views illustrating a method for manufacturing a circuit-formed substrate according to the first embodiment of the present invention. As shown in FIG. 1A, the substrate material 11 is a composite material of a thermosetting resin 12 and an aramid fiber 13 made of a woven or non-woven organic fiber material. The thermosetting resin 12 is not completely cured but is in a so-called B-stage state including an uncured portion, and the substrate material 11 is usually called a prepreg.

  Next, as shown in FIG. 1B, a laser beam 14 is irradiated onto the substrate material 11 to form a through hole 15. At that time, the thermosetting resin 12 and the aramid fiber 13 in the substrate material 11 are sublimated by heat and scattered around. When the processing conditions are appropriate as described later, the aramid fibers 13 are altered by melting or the like in the vicinity of the inner wall of the hole and integrated to form a deteriorated layer 16 as a diffusion preventing means. The altered layer 16 is mainly composed of the aramid fiber 13, but a part of the softened component of the thermosetting resin 12 may be mixed.

  Next, as shown in FIG. 1C, the through-hole 15 is filled with a conductive paste 17 as a connecting means mainly composed of conductive particles and an epoxy resin using a printing method or the like. Next, as shown in FIG. 1D, the metal foil 18 is superposed on both surfaces of the substrate material 11 and heated and pressed to compress the substrate material 11 in the thickness direction as shown in FIG. The metal foil 18 superposed on both surfaces of the substrate material 11 by the paste 17 is electrically joined. Thereafter, as shown in FIG. 1 (f), the metal foils 18 on both sides of the substrate material 11 are etched by a normal etching method to form a circuit 19 to be a circuit forming substrate.

  The altered layer 16 has a relatively dense film shape and is formed on the inner wall of the through-hole 15. The air gap is such that the resin component in the conductive paste 17 is discharged to the outside of the through-hole 15 during the pressure heating. Has. However, in the experiment using spherical conductive particles having a particle diameter of about 1 to 5 μm, almost no flow of conductive particles was confirmed outside the altered layer 16. When the size of the through hole 15 is miniaturized, it is necessary to use the conductive paste 17 having a low viscosity in order to improve the filling property of the conductive paste 17. Therefore, the viscosity is adjusted by reducing the ratio of the conductive particles in the conductive paste 17 and increasing the resin component, etc., but the electrical bonding of the metal foils 18 on both sides of the substrate material 11 is achieved by reducing the ratio of the conductive particles. The reliability of the system may be reduced.

  However, by performing compression by heating and pressing while selectively leaving only the conductive particles in the conductive paste 17 as described in the present embodiment inside the through hole 15, the compression in the through hole 15 after compression is performed. The reliability of joining can be improved by setting the density of the conductive particles sufficiently high. As can be seen from the contents described in the present embodiment, the expression of the altered layer 16 is used in the present invention for the sake of convenience. However, the layer is formed into a complete film and altered to the inner wall of the hole. The layer 16 is not necessarily formed, and it is only necessary to satisfy the condition that there is a portion having the property of preventing the diffusion of the connecting means in the vicinity of the inner wall of the hole. In the present invention, the altered layer 16 is used.

  The action of this embodiment is effective even when the substrate material 11 is a prepreg and is porous with many pores, and the present invention is also effective for a porous material that can be easily compression-molded.

(Embodiment 2)
FIG. 2 to FIG. 4 are a pulse waveform schematic diagram and a cross-sectional view of a processing part showing hole processing in the substrate material 11 in the second embodiment of the present invention.

  The substrate material 11 was formed by using a prepreg impregnated with a thermosetting resin in an aramid fiber non-woven fabric and B-staged by heating, and using a carbon dioxide gas laser as an energy beam. When the substrate material 11 is irradiated with a laser pulse having a steep rise and fall and a relatively high peak energy as shown in FIG. 2A, the thermosetting resin 12 and the aramid fiber 13 instantaneously evaporate and sublimate. As shown in FIG. 2B, the cut surface of the aramid fiber 13 appears on the inner wall of the hole in the form before processing, and the curing of the thermosetting resin 12 does not progress around the hole. According to the experiments of the present inventor, such processing was performed when the rise and fall times of the laser pulse were 20 μs or less and the peak energy was 1000 W or more for a prepreg having a thickness of about 200 μm. Further, the pulse width necessary to obtain a hole diameter of about 150 μm was less than about 50 μs as a half-value width.

  Next, when the substrate material 11 is irradiated with a laser pulse having a relatively low peak energy and a long fall time as shown in FIG. 3A, a cross section of the processed part as shown in FIG. 3B is obtained. . Since the peak power is low, the pulse width is inevitably long to perform the desired hole processing, and the fall time is also long, so that a heat storage phenomenon occurs near the processed portion, and the thermosetting resin 12 and the aramid fiber 13 The carbonized layer 29 is formed by carbonization in the vicinity of the inner wall, and the shape of the inner wall of the hole becomes extremely uneven due to the difference between the melting point and the processing rate. According to the experiments by the present inventors, such a phenomenon was observed when the peak power of the laser pulse was 100 W or less, the half width of the pulse was 1 ms or more, or the fall time was 1 ms or more.

  Next, as shown in FIG. 4 (a), when a pulse waveform corresponding to the middle of FIG. 2 (a) and FIG. 3 (a) is used, an aramid fiber is used as shown in FIG. 4 (b). A cross-sectional shape of the processed part in which the inner wall of the hole was covered as the film-like altered layer 16 by the component in which 13 was melted was obtained. Even when the hole 11a exists on the inner wall of the hole, the altered layer 16 does not cause the hole 11a to appear on the inner wall of the hole. In particular, when an aramid fiber 13 having a heat shrinkage starting temperature of 150 ° C. or higher and lower than 300 ° C. was used, the fiber was effectively degenerated by heat, and the film-like altered layer 16 was efficiently formed. As a matter of course, the components of the thermosetting resin 12 are also mixed in the deteriorated layer 16, but it does not affect the effect of the deteriorated layer 16, and depending on the physical properties of the thermosetting resin 12, it is formed by the aramid fibers 13. In some cases, an effect of complementing the voids of the altered layer 16 may be obtained.

  According to the experiments by the present inventors, all or one of the conditions in which the peak power of the laser pulse is in the range of about 100 W to 1000 W, the half width of the pulse is in the range of about 50 μs to 1 ms, and the fall time is in the range of about 20 μs to 1 ms. Such processing was realized when the part was filled. Specifically, when a hole having a diameter of 150 μm is drilled in a prepreg having a thickness of 200 μm, when one pulse of a laser beam having a pulse peak power of 500 W, a pulse half-value width of 250 μs, and a fall time of 50 μs is irradiated, The formation of a good altered layer 16 was confirmed. In another experiment, an excellent deteriorated layer 16 was obtained even when the peak power of the pulse was 400 W, the half width was 500 μs, and the fall time was 300 μs.

  The optimum processing conditions vary depending on the material, thickness, etc. of the substrate material 11, but in order to obtain a desired hole diameter, the peak power and half width (pulse width) of the pulse are changed to form a carbonized layer on the inner wall of the hole. The optimum value for obtaining the desired hole diameter without occurrence of the occurrence of the problem, that is, the minimum energy required for drilling is found, and when the deteriorated layer 16 is insufficiently formed, the fall time is in the range of about 50 to 200% of the half width. It is often possible to process a desired hole diameter having a preferable deteriorated layer 16 by applying the processing energy necessary for forming the deteriorated layer 16 by changing the above. However, since the adjustment range of the peak power and the half-value width is often limited by the structure of the energy beam generation source or the like, the energy amount may be adjusted using a mask or the like as will be described later.

(Embodiment 3)
5A to 5F are process cross-sectional views illustrating a method for manufacturing a circuit-formed substrate in the third embodiment of the present invention. The difference from the first embodiment of the present invention is that the substrate material is composed only of the thermosetting resin 12. Such a configuration can also be adopted depending on the required performance of the circuit forming substrate. Also in the present embodiment, diffusion of the conductive paste 17 is prevented by the formation of the altered layer 16 as in the first embodiment. Although both the first and third embodiments have been described with respect to the double-sided circuit formation substrate, it goes without saying that a multilayer circuit formation substrate can be obtained by repeating the steps. In addition, the use of a woven cloth instead of the non-woven cloth and the use of an organic fiber material other than aramid or an inorganic fiber material such as glass as the fiber constituting the woven or non-woven cloth, thermoplasticity instead of the thermosetting resin 12 It is also possible to use a resin.

(Embodiment 4)
FIG. 6 is a schematic configuration diagram showing a circuit forming substrate manufacturing apparatus according to the fourth embodiment of the present invention. The laser beam 14 derived from the laser beam oscillator 20 is incident on the mask 21 via the total reflection mirror 22 and the like, masked to a desired beam diameter, and is applied onto the substrate material 11 by the condensing lens 24 via the scanning means 23. Irradiated. In order to irradiate a desired position on the substrate material 11, a galvanometer mirror or the like that operates at high speed is used as the scanning means 23, and the substrate material 11 is fixed to an XY stage (not shown) or the like. It is done.

  Next, the operation will be described with reference to FIGS. As shown in FIG. 7A, the in-plane energy distribution of the laser beam shows a gentle distribution with the center at the apex. Although a simple shape called a single mode is shown in this embodiment mode, it is possible to use a laser beam oscillator having a mode called a multimode having several peaks in the outer peripheral direction from the center. When the substrate material 11 is irradiated with such a laser beam, as shown in FIG. 7B, hole processing is performed on the substrate material 11 and the altered layer 16 is formed due to thermal influence on the periphery of the hole. In the portion where the energy density around the laser beam is small, the amount of energy necessary for removing the substrate material 11 does not reach, so the altered layer 16 is formed only on the surface portion of the substrate material 11, and the altered layer 16 is formed on the substrate as shown in the figure. It is formed so as to spread toward the surface.

  When such a substrate material 11 is used for the application as in the third embodiment described above, the altered layer 16 is formed in a portion other than the portion necessary for preventing the diffusion of the connecting means. This is a hindrance when the substrate material 11 is compression-molded by pressure, and the reliability of the connecting means is low. For this reason, a mask 21 as shown in FIG. 6 is used so that a portion with a small energy distribution around the laser beam does not reach the substrate material 11.

  FIG. 8 shows the state of processing when the mask 21 is used. As shown in FIG. 8A, the portion indicated by the dotted line of the laser beam, that is, the peripheral portion having a low energy density is cut by the mask 21. Therefore, as shown in FIG. 8B, the altered layer 16 is not formed around the hole more than necessary, but is formed only near the inner wall of the hole.

  Further, FIG. 9 shows a processing state when the selection width of the laser beam by the mask 21 is narrowed. As shown in FIG. 9A, only the portion having a high energy density near the center of the laser beam is selected and irradiated onto the substrate material 11. In this case, the processed cross section has no deteriorated layer 16 as shown in FIG. In the case of such processing, the hole diameter obtained is approximately equal to the spot diameter when the laser beam is irradiated onto the substrate material 11. When such a substrate material 11 is used for an application such as that shown in Embodiment 3, diffusion of the conductive paste around the hole occurs during compression molding.

  According to the experiment by the present inventor, when the light flux selected by the mask 21, that is, the light flux acting on the processing is 2% or less of the light flux of the laser beam 14 reaching the mask 21, the phenomenon shown in FIG. . That is, when the luminous flux incident on the mask 21, that is, the beam diameter is 10 mm, and the hole diameter for passing the beam formed in the mask 21 is 1 mm, the luminous flux is 1% as an area ratio. However, only the substrate material 11 can be reached, and as shown in FIG.

  Further, when the quality of the laser beam 14 derived from the laser beam oscillator 20 is very good, the mask 21 may not be necessary. In this case, the substrate material 11 irradiated with a portion having a small energy distribution around the laser beam becomes a processing condition in which the altered layer 16 is easily formed, and as a result, a preferred altered layer 16 is obtained on the inner wall of the hole.

  Further, also in the hole machining as shown in FIG. 9, when the irradiation time of the laser beam 14 is extended from the minimum time necessary for hole formation, the thermal influence due to the irradiation of the laser beam 14 is sequentially affected by the processed portion. Propagating nearby, the hole diameter increases with irradiation time. In this case, the altered layer 16 may be formed in the vicinity of the inner wall of the hole without reaching the temperature condition where the substrate material 11 evaporates and sublimates. However, if the irradiation time is further extended, carbides are generated in the holes. The formation of a preferable altered layer 16 is observed when the hole diameter is increased to about 110 to 300% of the laser beam spot diameter on the substrate material 11, and when the hole diameter is further increased, the formation of carbide Problems such as generation and unevenness of the inner wall of the hole become significant. In other words, a laser beam diameter of about 30 to 90% of the desired hole diameter may be used.

  One definition of the processing conditions for obtaining the preferred altered layer 16 is described below. When the minimum amount of energy required to form a through-hole or non-through-hole in the substrate material 11 is used, and the pulse width and fall time of the irradiated laser beam are sufficiently short and do not affect the surroundings of the hole. In this processing, the in-plane temperature distribution of the processed portion at the time of hole formation is a steep distribution in which only the hole processed portion is equal to or higher than a threshold necessary for removal processing, and the substrate material 11 corresponding to the volume of the hole is removed. Thus, there is no generation of the altered layer 16 on the inner wall of the hole.

  In order to obtain a preferable deteriorated layer 16, the hole processing portion should have a threshold value that is equal to or higher than a threshold necessary for the removal processing, and a relatively gentle temperature distribution that provides a temperature condition suitable for forming the deteriorated layer 16. In addition, it is necessary to prevent the thermal effect from spreading on the substrate material 11 more than necessary. For this purpose, the altered layer 16 has a minimum energy amount necessary for forming the above-described through-hole or non-through-hole. It is necessary to irradiate the substrate material 11 with a laser pulse to which an energy amount necessary for forming the substrate is added. As the method, it is effective to extend the pulse width and the fall time or use the energy density distribution from the center of the laser beam toward the peripheral portion as described in the above embodiment.

(Embodiment 5)
FIG. 10 is a process cross-sectional view illustrating a circuit forming substrate manufacturing method according to the fifth embodiment of the present invention. As the substrate material 11, a multilayer circuit forming substrate material on which an inner layer circuit as shown in FIG. The inner layer circuit 25 is formed of a metal foil and a plating layer, and a composite material of the aramid fiber 13 and the thermosetting resin 12 is used for the insulating layer. Next, as shown in FIG. 10B, non-through holes 26 are formed on the surface of the substrate material 11 by irradiation with a laser beam (not shown). At this time, the altered layer 16 is simultaneously formed on the inner wall of the non-through hole 26 by optimizing the processing conditions. When a carbon dioxide laser is used, it is easy to process a non-penetrating shape as shown in the figure by taking advantage of poor processability to metal foil.

  Next, a plating layer 27 is formed on the surface of the substrate material 11 as shown in FIG. The plating layer 27 is connected to the inner layer circuit 25 in the non-through hole 26. When the plating layer 27 is formed, penetration of the plating solution into the substrate material 11 is prevented by the action of the altered layer 16. Finally, the plating layer 27 is patterned to obtain a multilayer substrate as shown in FIG.

  In the above embodiment, the carbon dioxide laser is used as the energy beam. However, other gas lasers and solid lasers such as YAG lasers, excimer lasers, or energy beams other than lasers can be used.

(Embodiment 6)
FIG. 11 is a process cross-sectional view illustrating a circuit forming substrate manufacturing method according to the sixth embodiment of the present invention. A substrate material 11 shown in FIG. 11A is a plate-like material made of a thermosetting resin 12, and a film 31 is bonded to both surfaces by a method such as lamination. For the film 31, an organic material such as polyethylene terephthalate or a metal foil can be used. Next, as shown in FIG. 11B, a through hole 15 is formed using a laser beam 14. Next, as shown in FIG. 11C, a resin layer 32 is formed on the substrate material 11 by dipping or spraying. The material of the resin layer 32 is preferably a thermosetting resin diluted with a solvent, and it is desirable to increase the hardness of the resin layer 32 by removing the solvent in a drying furnace after application.

  Next, as shown in FIG. 11D, the film 31 is peeled to obtain the substrate material 11 in which the resin layer 32 is formed only on the inner wall portion of the through hole 15. The resin layer 32 formed in this manner has the same effect as the altered layer 16 described in the third embodiment of the present invention, and can prevent the connecting means from diffusing around the through hole 15 in the subsequent process. Is. In the above embodiment, resin is used as the diffusion preventing means, but a similar effect can be obtained by forming a thin film on the substrate material 11 by means such as sputtering.

(Embodiment 7)
FIG. 12 is a process cross-sectional view illustrating a circuit forming substrate manufacturing method according to a seventh embodiment of the present invention. A substrate material 11 shown in FIG. 12A is a plate-like material made of a thermosetting resin 12 and is B-staged as described in the above-described embodiment. Next, as shown in FIG. 12B, a through hole 15 is formed using a laser beam 14. Next, as shown in FIG. 12 (c), the conductive paste 17 is filled into the through holes 15. Adding a material that reacts with the thermosetting resin 12 to the conductive paste 17 forms a cured layer 33 near the wall surface of the through hole 15. Since the thermosetting resin 12 is completely cured from the B stage in a later step, the curing agent is latent at this stage. Therefore, by adding a highly active curing agent to the conductive paste 17, the cured layer 33 can be formed on the contact surface between the conductive paste 17 and the thermosetting resin 12 at the stage of FIG. Thereafter, the circuit forming substrate can be manufactured by carrying out the steps as described in the third embodiment of the present invention, and the hardened layer 33 exhibits the effect as a diffusion preventing means. It is.

(Embodiment 8)
FIG. 13 is a schematic configuration diagram showing a circuit forming substrate manufacturing apparatus according to the eighth embodiment of the present invention. The laser beam 14 derived from the laser beam oscillator 20 enters the shutter 34 via the total reflection mirror 22 and the like, and is irradiated onto the substrate material 11 by the condenser lens 24 via the scanning unit 23. In order to irradiate a desired position on the substrate material 11, a galvanometer mirror or the like that operates at high speed is used as the scanning unit 23, and the substrate material 11 is fixed to an XY stage (not shown) or the like. .

  By opening and closing the shutter 34, the pulse width of the laser beam 14 applied to the substrate material 11 can be set to a desired value. Although it is possible to adjust the pulse width of the laser beam 14 by changing the pulse width of the oscillation command signal given to the laser beam oscillator 20, the degree of freedom of the pulse width obtained when using the shutter 34 is higher. . More preferably, the laser beam 14 is controlled by an operation under two conditions: the pulse width of the oscillation command signal and the opening / closing time of the shutter 34.

  Using the laser processing apparatus configured as described above, the pulse width of the laser beam 14 irradiated onto the substrate material 11 is set to the time required for removing the portion of the substrate material 11 irradiated with the laser beam 14. In addition, the time required for obtaining a hole diameter of 110 to 300% of the energy beam diameter on the substrate material 11 due to the heat effect on the periphery of the removed substrate material 11 in order to enlarge the hole diameter. When the above-described processing conditions were set such that the pulse width of the laser beam 14 irradiated onto the substrate material 11 was within a range of 50 μs to 1 ms in half width, preferable hole processing was realized.

(Embodiment 9)
FIG. 14 is a perspective view showing a laser oscillation unit of a circuit forming board manufacturing apparatus according to the ninth embodiment of the present invention. A discharge voltage (not shown) is applied between the upper and lower discharge electrodes 35, and the laser medium gas passes at a constant flow rate in the gas flow direction 38 and the illustrated direction. The excited particles 36 are molecules of a laser medium gas and are excited by a discharge phenomenon generated between the discharge electrodes 35. A laser beam is generated when the excited particles 36 return from the excited state to the normal state, and the generated laser beam is Amplified in the oscillating portion and taken out from the aperture 39 toward the laser lead-out direction 37.

  As can be understood from such a configuration, only the laser beam generated at the projection portion of the aperture 39 indicated by the dotted line portion in FIG. 14 is extracted to the outside. The time from when the application of the discharge voltage is stopped until the derived laser beam intensity falls is that the excited particles 36 sandwiched between the upper and lower discharge electrodes 35 at the time when the application of the discharge voltage is stopped are indicated by dotted lines in the figure. It is determined by the time required to pass through all the projected portions of the aperture 39 shown. That is, the fall time can be set to a desired value depending on the gas flow speed, the width of the discharge electrode 35, and the position of the aperture 39. For example, when the discharge electrode 35 has a width of 50 mm and an aperture 39 is provided near the center of the discharge electrode 35 and the gas flow rate is 80 m / sec, a fall time of about 300 μs can be obtained, and the formation of a preferable deteriorated layer 16 can be confirmed.

(A)-(f) Process sectional drawing of the manufacturing method of the circuit formation board | substrate of the 1st Embodiment of this invention. (A) Schematic diagram of pulse waveform of manufacturing method of circuit forming substrate according to second embodiment of present invention (b) Sectional view of the processed part (A) Schematic diagram of pulse waveform of manufacturing method of circuit forming substrate according to second embodiment of present invention (b) Sectional view of the processed part (A) Schematic diagram of pulse waveform of manufacturing method of circuit forming substrate according to second embodiment of present invention (b) Sectional view of the processed part (A)-(f) Process sectional drawing of the manufacturing method of the circuit formation board | substrate of the 3rd Embodiment of this invention. The schematic block diagram of the manufacturing apparatus of the circuit formation board of the 4th Embodiment of this invention (A) Laser beam energy distribution diagram of a circuit forming board manufacturing apparatus according to a fourth embodiment of the present invention (b) Cross section of the processed part (A) Laser beam energy distribution diagram of a circuit forming board manufacturing apparatus according to a fourth embodiment of the present invention (b) Cross section of the processed part (A) Laser beam energy distribution diagram of a circuit forming board manufacturing apparatus according to a fourth embodiment of the present invention (b) Cross section of the processed part (A)-(d) Process sectional drawing of the manufacturing method of the circuit formation board | substrate of the 5th Embodiment of this invention. (A)-(d) Process sectional drawing of the manufacturing method of the circuit formation board | substrate of the 6th Embodiment of this invention. (A)-(c) Process sectional drawing of the manufacturing method of the circuit formation board | substrate of the 7th Embodiment of this invention. The schematic block diagram of the manufacturing apparatus of the circuit formation board of the 8th Embodiment of this invention The schematic block diagram of the manufacturing apparatus of the circuit formation board of the 9th Embodiment of this invention (A), (b) Sectional drawing of the manufacturing method of the conventional circuit formation board | substrate (A), (b) Cross-sectional view of a conventional double-sided circuit-formed substrate Sectional view of a conventional circuit board

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Board | substrate material 12 Thermosetting resin 13 Aramid fiber 14 Laser beam 15 Through-hole 16 Alteration layer 17 Conductive paste 18 Metal foil 19 Circuit 20 Laser beam oscillator 21 Mask 22 Total reflection mirror 23 Scanning means 24 Condensing lens 25 Circuit 26 Non-penetration Hole 27 Plating layer 29 Carbonized layer 32 Resin layer 33 Hardened layer 34 Shutter 35 Discharge electrode 36 Excited particles 37 Laser exit direction 38 Gas flow direction 39 Aperture

Claims (28)

A step of preparing a plate-like or sheet-like substrate material composed of a single material or a plurality of materials, and processing a through-hole or a non-through-hole of a desired hole diameter in the substrate material, and at the same time, preventing diffusion on the inner wall of the hole A circuit forming substrate manufacturing method comprising: a hole forming step of irradiating an energy beam under a condition where the means remains; and a step of forming a connecting means with a conductive material in the hole where the diffusion preventing means remains. 2. The irradiation condition of the energy beam is a condition in which the substrate material is melted and re-solidified to leave the altered layer as a film-like diffusion preventing means so as to cover a part or the whole of the inner wall of the hole. A method for producing a circuit-formed substrate as described in 1. The circuit forming substrate manufacturing method according to claim 2, wherein the energy beam is a laser beam. The method for manufacturing a circuit forming substrate according to claim 3, wherein the laser beam is a carbon dioxide gas laser. The energy beam irradiation condition is the amount of energy of the energy beam, the amount of energy required to process the desired hole dimensions, and the energy required for the altered layer formed on the inner wall of the hole to remain without carbonization. 3. The method for manufacturing a circuit-formed substrate according to claim 2, wherein the amount of energy is equal to or greater than the amount of energy and the amount of energy is less than or equal to the amount of energy for generating a carbide layer on the inner wall of the hole or generating an uneven shape on the inner wall of the hole. 2. The method for manufacturing a circuit-formed substrate according to claim 1, wherein the irradiation condition of the energy beam is a condition in which the energy beam diameter on the substrate material is set to 30 to 90% of a desired hole diameter. The irradiation condition of the energy beam is a condition set to an irradiation time in which a through or non-through hole diameter to be processed reaches a hole diameter of 110 to 300% of an energy beam diameter irradiated onto the substrate material. A method for producing a circuit-formed substrate as described in 1. 2. The method for manufacturing a circuit-formed substrate according to claim 1, wherein the irradiation condition of the energy beam is a condition in which a pulse width of the energy beam irradiated onto the substrate material is set within a range of 50 μs to 1 ms as a half width. The irradiation condition of the energy beam is to set the intensity of irradiation with respect to the time axis of irradiation. The half-value width time with respect to the peak value of intensity is set to t1, and the intensity from this peak value to 1 / square of the peak value e. 2. The method for manufacturing a circuit-formed substrate according to claim 1, wherein t2 is a condition set such that t2 is 50% or more and less than 200% of t1, where t2 is the falling time. The irradiation condition of the energy beam is to set the intensity of irradiation with respect to the irradiation time axis, and the time for the intensity to fall from the peak value to 1 / square of the peak value e is within the range of 20 μs or more and 1 ms or less. The method for manufacturing a circuit forming substrate according to claim 1, wherein the conditions are set as follows. 2. The circuit forming substrate according to claim 1, wherein the irradiation condition of the energy beam is a condition for cutting the energy beam from the periphery up to 98% of the energy beam derived from the energy beam oscillator. Method. 2. The method for manufacturing a circuit-formed substrate according to claim 1, wherein the irradiation condition of the energy beam is a condition for setting a peak energy of an energy beam pulse derived from an energy beam generator as 100 W or more and 3000 W or less. A plate-like or sheet-like substrate material made of a single material or a plurality of materials is irradiated with an energy beam to form a through or non-through hole, and at the same time the connection means is formed with a conductive paste in the hole. A method for manufacturing a circuit-formed substrate, comprising a step of forming diffusion preventing means formed of the substrate material and a material that reacts with a thermosetting resin in the conductive paste in the vicinity of an inner wall of a hole. The method for manufacturing a circuit forming substrate according to claim 1, wherein the conductive substance is a paste containing conductive particles. The method for manufacturing a circuit-formed substrate according to claim 14, wherein the conductive particles are selected to have a particle size that is difficult to pass through the diffusion preventing means. The step of forming the connecting means includes a procedure in which a metal foil is disposed on one or both sides of a substrate material filled with a paste containing conductive particles, and the substrate material in which the metal foil is disposed on one or both sides is heated and pressed to compress it. A method for manufacturing a circuit forming substrate according to claim 13. The paste used for filling is a paste having a feature that an amount of components other than the conductive particles discharged outside the diffusion preventing means is larger than that of the conductive particles when compressed by heating and pressing. A method for manufacturing a circuit-formed substrate. The method for manufacturing a circuit forming substrate according to claim 1, wherein the conductive material is metal plating. The method for producing a circuit-formed substrate according to claim 1 or 13, wherein at least a portion of the substrate material for forming a hole is a resin film containing an uncured portion. The method for manufacturing a circuit-formed substrate according to claim 1 or 13, wherein the substrate material is a woven fabric or a composite material of a nonwoven fabric and a resin. 21. The method of manufacturing a circuit forming substrate according to claim 19, wherein the resin is thermosetting. The method for manufacturing a circuit forming substrate according to claim 21, wherein the resin is in a B-stage state including an uncured component. 21. The method of manufacturing a circuit forming substrate according to claim 20, wherein an organic fiber material is used for the woven fabric or the nonwoven fabric. The method for producing a circuit forming substrate according to claim 23, wherein an aromatic polyamide fiber is mainly used as the organic fiber material. The method for producing a circuit-formed substrate according to claim 23, wherein the heat shrinkage start temperature of the organic fiber material is 150 degrees or more and less than 300 degrees. The method for producing a circuit forming substrate according to claim 13, wherein the diffusion preventing means formed on the inner wall of the hole, or a part thereof, is a deteriorated layer mainly composed of a component in which a woven fabric or a non-woven fabric has been altered by melting or the like. The method for producing a circuit-formed substrate according to claim 13, wherein the diffusion preventing means formed on the inner wall of the hole, or a part thereof, is formed by integrating a component in which the woven fabric or nonwoven fabric has been altered by melting or the like and a portion in which the resin is altered. The method for manufacturing a circuit forming substrate according to claim 13, wherein the substrate material is porous.

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