JP2007281431A - Method of manufacturing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a circuit board which can prevent holes formed through a circuit board from being closed with machining chips. <P>SOLUTION: This method of manufacturing a circuit board comprises the processes of: a hole forming process in which a pass-through hole 18 is formed through an insulating substrate 10 which contains a resin composition; and then a heating process in which the insulating substrate 10 is heated to a temperature higher than the heat-softening temperature and lower than the heat-hardening temperature of the insulating substrate 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a substrate such as a circuit board.

  With recent downsizing and higher density of electronic devices, as a circuit board on which electronic components are mounted, a double-sided board and a multilayer board are being adopted in addition to the conventional single-sided board. As described above, development of a high-density circuit board capable of integrating a larger number of circuits on the board has been performed.

  For high-density circuit boards, the adoption of laser processing methods that enable finer hole processing at higher speeds instead of drilling holes (through-holes) for connecting to the substrate, which have been widely used in the past, has been considered. ing.

There has also been proposed a circuit board that performs interlayer connection using fine hole processing by a laser and connection means such as a conductive paste (see, for example, Patent Document 1).
JP-A-6-268345

  In a circuit board in which fine holes are formed and interlayer connection is made using a conductive paste, a slight amount of foreign matter causes connection failure. In this circuit board, holes are processed together with the film attached to the board. This film is used as a mask for filling the fine holes with the conductive paste. Therefore, it is necessary to keep everything including the film clean.

  However, in processing such as cutting, drilling, and laser processing, a large amount of processing waste (resin powder) is generated. When this processing waste adheres to the hole, the hole may be blocked.

  Here, after processing such as cutting, drilling, and laser processing, it is known that the substrate surface and the inside of the hole are cleaned with a cleaning roll, a blower, a rotating brush, a suction device, and the like. However, there is a case where processing waste in the substrate end and the hole falls off during conveyance after the cleaning, and the connection hole is closed again. Thus, it is not sufficient to clean the substrate surface and the inside of the hole.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a substrate that can prevent processing scrapes from blocking holes formed in the substrate.

  In order to solve the above-described problems, a substrate manufacturing method of the present invention includes a hole forming step of forming a hole in a substrate containing a resin composition, and a softening temperature of the substrate or higher after the hole forming step. Heating the substrate at a temperature not higher than the curing temperature.

  In the substrate manufacturing method of the present invention, in the heating step, the processing waste generated mainly from the substrate in the hole forming step and the substrate are softened or dissolved, so that the processing waste can be integrated with the substrate. When the heating temperature is lower than the softening temperature, the processing waste and the substrate are not softened or dissolved. On the other hand, if the heating temperature is higher than the curing temperature, the substrate is cured and the moldability of the substrate is lowered. Therefore, according to the manufacturing method of the board | substrate of this invention, it can suppress that a hole is plugged up with processing waste.

  Moreover, it is preferable that the manufacturing method of the said board | substrate further includes the cutting process which cut | disconnects the said board | substrate to a predetermined dimension before the said heating process. In addition, the execution order of a cutting process and a hole formation process is not specifically limited. The hole forming step may be performed after the cutting step, the cutting step may be performed after the hole forming step, or the cutting step and the hole forming step may be performed simultaneously. In this case, the processing waste generated in the cutting process can be integrated with the substrate in the heating process. Therefore, it is possible to further suppress the hole from being blocked by the processing waste.

  The substrate manufacturing method preferably further includes a cleaning step of cleaning the substrate between the hole forming step and the heating step. In this case, by cleaning the substrate, it is possible to remove processing waste adhering to the substrate in the hole forming step. Therefore, it can further suppress that a hole is plugged up with processing waste.

  Further, the substrate may be an insulating substrate, and the hole may be a through hole. Further, the insulating substrate may be a prepreg formed by impregnating a glass woven fabric or a nonwoven fabric with a thermosetting resin composition and forming the thermosetting resin composition into a B-stage.

  Moreover, it is preferable that the manufacturing method of the said board | substrate further includes the filling process which fills the said through-hole with an electrically conductive paste after the said heating process. In this case, since it is possible to prevent the through hole from being blocked by the processing waste, a sufficient conductive paste can be filled in the through hole. Therefore, poor connection of through holes can be suppressed.

  Moreover, it is preferable to form the through hole in the insulating substrate using a laser. In this case, since the amount of processing waste generated when forming the through hole can be suppressed, it is possible to further suppress the through hole from being blocked by the processing waste.

  Moreover, it is preferable that a peelable resin film is laminated on at least one surface of the insulating substrate. In this case, the amount of processing waste generated in the hole forming step is reduced.

  Moreover, the manufacturing method of the said board | substrate may further include the 1st heating-pressing process of heating-pressing what laminated | stacked metal foil on both surfaces of the said prepreg after the said heating process.

  The substrate manufacturing method preferably further includes a patterning step of patterning the metal foil after the first heating and pressing step. Thereby, a circuit board can be manufactured.

  Moreover, the manufacturing method of the said board | substrate makes the board | substrate obtained by the manufacturing method of the said board | substrate an inner-layer circuit board, The 2nd heating-pressing process of heating and pressurizing what laminated | stacked the prepreg and metal foil on both surfaces of the said inner-layer circuit board is carried out. It is preferable that it is further included. In this case, a multilayer circuit board can be manufactured.

  Further, the substrate manufacturing method comprises heating the substrate obtained by the substrate manufacturing method as an inner circuit board, a plurality of the inner circuit boards and prepregs being alternately stacked, and a metal foil being stacked on the outermost layer. It is preferable to further include a second heating and pressurizing step for applying pressure. In this case, a multilayer circuit board can be manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the board | substrate which can suppress that a process waste block | closes the hole formed in the board | substrate is provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

  1 and 2 are cross-sectional views schematically showing each step of the substrate manufacturing method according to the embodiment. Hereinafter, a method for manufacturing the circuit board 100 shown in FIG. 2C will be described.

(Cutting process)
First, as shown in FIG. 1A, an insulating substrate 10 (substrate) containing a resin composition is cut into a predetermined dimension along a cutting line C1. Examples of the resin composition contained in the insulating substrate 10 include an epoxy resin, a phenol resin, a polyimide resin, a polyester resin, a silicone resin, a cyanate resin, a polyphenylene ether resin, a polyphenylene oxide resin, and a melamine resin. Removable resin films 12 and 14 such as a polyethylene terephthalate sheet (hereinafter referred to as “PET sheet”) may be laminated on both surfaces of the insulating substrate 10, respectively. In this case, the resin films 12 and 14 are also cut together with the insulating substrate 10. The insulating substrate 10 is preferably a prepreg formed by impregnating a glass woven fabric or a nonwoven fabric with a thermosetting resin composition and forming the thermosetting resin composition into a B-stage.

(Hole formation process)
Next, as shown in FIG. 1B, a through hole 18 (hole) is formed in the insulating substrate 10. The through hole 18 is formed using, for example, a laser L emitted from the laser light source 16. Note that cutting means other than the laser L (for example, a drill or the like) may be used. When the resin films 12 and 14 are laminated on both surfaces of the insulating substrate 10, through holes are formed in the resin films 12 and 14 together with the insulating substrate 10. The diameter of the through hole 18 is preferably 150 μm or less, and more preferably 120 μm or less.

(Cleaning process)
Next, as shown in FIG. 1C, the insulating substrate 10 is cleaned using, for example, a cleaning device 20. Examples of the cleaning device 20 include a cleaning roll, a blower, a rotating brush, a suction device, or a combination thereof. In particular, it is preferable to clean the inside of the through hole 18. When the diameter of the through hole 18 is 150 μm or less, the cleaning effect is particularly high.

(Heating process)
Next, as shown in FIG. 1D, the insulating substrate 10 is heated at a temperature not lower than the softening temperature of the insulating substrate 10 and not higher than the curing temperature of the insulating substrate 10 using, for example, a heat source 22. For example, it is preferable to heat the insulating substrate 10 at 50 ° C. or higher and 205 ° C. or lower. When heating, it is preferable to heat the vicinity of the through hole 18. Moreover, when performing a cutting process, it is preferable to heat the cutting part (part near cutting line C1) of the insulating substrate 10.

  The softening temperature can be measured using, for example, a DSC (Differential Scanning Calorimeter). The curing temperature can be the maximum value of Heat Flow at the exothermic peak of the DSC chart. The softening temperature can be the temperature of the minimum value of Heat Flow at the endothermic peak of the DSC chart.

  In order to heat the insulating substrate 10, for example, a heatable roll may be passed through the through hole 18, the insulating substrate 10 may be sandwiched between two heatable plates, infrared rays, hot air, high frequency Alternatively, magnetic field lines may be used. Moreover, you may use these heating methods together.

  When the insulating substrate 10 is heated at a temperature lower than the softening temperature of the insulating substrate 10, the resin composition constituting the insulating substrate 10 is not softened or dissolved. On the other hand, when the insulating substrate 10 is heated at a temperature higher than the curing temperature of the insulating substrate 10, the performance of the insulating substrate 10 changes, and blurring and voids are likely to occur in the heating and pressurizing process described later.

  When the temperature at which voids are not confirmed when the resin films 12 and 14 are laminated on the insulating substrate 10 is T1 (° C.), the heating temperature of the insulating substrate 10 is preferably (T1 + 30) ° C. or less. When the heating temperature exceeds (T1 + 30) ° C., the adhesiveness between the insulating substrate 10 and the resin films 12 and 14 is lowered, and thus the resin films 12 and 14 tend to be easily peeled after lamination. As a result, the conductive paste 24 may penetrate between the insulating substrate 10 and the resin films 12 and 14 in a filling process described later, which may cause a short circuit or the like.

(Filling process)
Next, as shown in FIG. 2A, the conductive paste 24 is filled into the through holes 18 by using, for example, a printing method. Thereby, a through hole is formed. The resin films 12 and 14 function as a mask in the filling process. Thereafter, the resin films 12 and 14 are peeled and removed as necessary.

(First heating and pressing step)
Next, as shown in FIG. 2B, the metal substrate 26 and 28 laminated on both sides of the insulating substrate 10 is heated and pressurized. The metal foils 26 and 28 are, for example, copper foils. In this way, the metal foils 26 and 28 are electrically connected by the conductive paste 24.

(Patterning process)
Next, as shown in FIG. 2C, circuit patterns 26a and 28a are formed by patterning the metal foils 26 and 28, for example, using a photolithography method. The circuit patterns 26 a and 28 a are electrically connected by the conductive paste 24. In this way, the circuit board 100 can be manufactured.

  3 and 4 are cross-sectional views schematically showing one step of the method for manufacturing a substrate according to another embodiment. Hereinafter, a method for manufacturing the multilayer circuit boards 200 and 300 shown in FIGS. 3 and 4 will be described. Similar to the above embodiment, the cutting process to the patterning process are performed. After the patterning step, the following second heating and pressing step is performed.

(Second heating and pressing step)
As shown in FIG. 3, the circuit board 100 is an inner circuit board, and a laminate in which a prepreg 30 and a metal foil 32 are laminated on both surfaces of the inner circuit board is heated and pressed. In this case, the multilayer circuit board 200 can be manufactured. As the prepreg 30, the same thing as the insulating substrate 10 can be used. As the metal foil 32, the same metal foils 26 and 28 can be used.

  Further, as shown in FIG. 4, the circuit board 100 is used as an inner circuit board, a plurality of inner circuit boards and prepregs 40 are alternately stacked, and a metal foil 42 stacked on the outermost layer is heated and pressurized. In this case, the multilayer circuit board 300 can be manufactured. As the prepreg 40, the same material as the insulating substrate 10 can be used. As the metal foil 42, the same metal foils 26 and 28 can be used.

  As described above, in the substrate manufacturing method according to the embodiment, in the heating process, the processing waste generated mainly from the insulating substrate 10 and the insulating substrate 10 in the hole forming step are softened or melted. 10 can be integrated. When the heating temperature is lower than the softening temperature, the processing waste and the insulating substrate 10 are not softened or dissolved. On the other hand, when the heating temperature is higher than the curing temperature, the insulating substrate 10 is cured, so that the moldability of the insulating substrate 10 is deteriorated. Therefore, according to the substrate manufacturing method of the embodiment, the through hole 18 can be prevented from being blocked by the processing waste. As a result, it is possible to prevent the processing waste from dropping from the end portion of the insulating substrate 10 and the inside of the through hole 18 while the insulating substrate 10 is being transported. Therefore, the occurrence of poor connection of through holes can be suppressed. Furthermore, since the heating temperature is equal to or lower than the curing temperature, it is possible to suppress a decrease in moldability of the insulating substrate 10. Therefore, in the first heating and pressurizing step, voids or the like are less likely to be generated between the insulating substrate 10 and the metal foils 26 and 28, so that the adhesion between the insulating substrate 10 and the metal foils 26 and 28 is improved. Can do.

  Moreover, when implementing a cutting process, the processing waste generated in the said cutting process can be integrated with the insulated substrate 10 in a heating process. Therefore, it is possible to further suppress the through hole 18 from being blocked by the processing waste.

  Moreover, when performing a cleaning process, the processing waste adhering to the insulated substrate 10 in the hole formation process can be removed. Therefore, it can further suppress that the through-hole 18 is blocked by the processing waste.

  Moreover, when performing a filling process, since it can suppress that the through-hole 18 is obstruct | occluded with a process waste, the sufficient electroconductive paste 24 can be filled in the through-hole 18. Therefore, poor connection of through holes can be suppressed.

  Moreover, when forming the through-hole 18 using the laser L, since the amount of processing waste generated when forming the through-hole 18 can be suppressed, it is further prevented that the through-hole 18 is blocked by the processing waste. Can be suppressed.

  Moreover, when the resin films 12 and 14 are laminated on both surfaces of the insulating substrate 10, the amount of processing waste generated in the hole forming process is reduced.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

  For example, one or more of the cutting process, the cleaning process, the filling process, the first heating and pressing process, and the second heating and pressing process may be performed, or the entire process may not be performed. .

  Further, for example, a semiconductor substrate or a conductor substrate may be used in place of the insulating substrate 10. Furthermore, instead of the through hole 18, a hole that does not penetrate may be formed in the insulating substrate 10.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
As an insulating substrate, a glass woven fabric is impregnated with a thermosetting resin composition, and a 500 mm width roll-shaped prepreg (made by Hitachi Chemical Co., Ltd., product name) is obtained by converting the thermosetting resin composition into a B-stage. GEA-67BE (t0.06)) was prepared. The softening temperature of the prepreg was 50 ° C. and the curing temperature was 205 ° C. Subsequently, a PET sheet having a thickness of 20 μm was laminated on both sides of the prepreg with a 140 ° C. heating roll.

  Next, the prepreg laminated with the PET sheet was cut into a length of 400 mm (cutting step). Thereafter, a through hole having a diameter of 200 μm was formed at a predetermined position using a laser (hole forming step).

  Next, the prepreg in which the through-hole was formed was heated at 140 degreeC using the infrared heater (heating process). Thereafter, the conductive paste was filled into the through holes using a printing method (filling step).

  Next, the PET sheet laminated on both sides of the prepreg was peeled and removed. Then, what laminated | stacked copper foil on both surfaces of the prepreg was heat-pressed with the hot press (1st heat-pressing process). In this way, the copper foils were electrically connected with the conductive paste. Furthermore, the copper foil was patterned into a desired shape (patterning step). In this way, a circuit board having circuit patterns formed on both sides was obtained.

(Example 2)
A circuit board was obtained in the same manner as in Example 1 except that a through hole having a diameter of 120 μm was formed in the hole forming process, and a cleaning process using a cleaning roll and a blower was performed between the hole forming process and the heating process. It was.

(Example 3)
A circuit board was obtained in the same manner as in Example 1 except that a through hole having a diameter of 120 μm was formed in the hole forming step.

(Comparative Example 1)
In the heating step, a circuit board was obtained in the same manner as in Example 1 except that the prepreg in which the through holes were formed was heated at 40 ° C.

(Comparative Example 2)
In the heating step, a circuit board was obtained in the same manner as in Example 1 except that the prepreg in which the through holes were formed was heated at 210 ° C.

(Comparative Example 3)
A circuit board was obtained in the same manner as in Example 3 except that the heating step was not performed.

(Evaluation results)
About the circuit board obtained in Examples 1-3 and Comparative Examples 1-3, the adhesiveness of a prepreg and a PET sheet, the moldability of a prepreg, and the clogging rate of a through-hole were evaluated. The results are shown in Table 1. The adhesion between the prepreg and the PET sheet was evaluated by visually confirming peeling between the prepreg and the PET sheet. The moldability of the prepreg was evaluated by removing all the upper and lower copper foils of the circuit board by etching and visually confirming the presence or absence of blur (voids found in the glass cloth). The occurrence rate of clogging of the through hole was calculated as “(number of clogged holes) ÷ (number of processed holes) × 100” by measuring the resistance of the circuit board and clogging open through holes.

It is sectional drawing which shows typically each process of the manufacturing method of the board | substrate which concerns on embodiment. It is sectional drawing which shows typically each process of the manufacturing method of the board | substrate which concerns on embodiment. It is sectional drawing which shows typically 1 process of the manufacturing method of the board | substrate which concerns on another embodiment. It is sectional drawing which shows typically 1 process of the manufacturing method of the board | substrate which concerns on another embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Insulating substrate, 2,14 ... Resin film, 18 ... Through-hole, 24 ... Conductive paste, 26, 28, 32, 42 ... Metal foil, 30, 40 ... Pre-preg, 100 ... Circuit board, 200, 300 ... Multilayer Circuit board, L ... Laser.

Claims (12)

A hole forming step of forming a hole in the substrate containing the resin composition;
A heating step of heating the substrate at a temperature not lower than the softening temperature of the substrate and not higher than the curing temperature of the substrate after the hole forming step;
A method for manufacturing a substrate, comprising:   The method for manufacturing a substrate according to claim 1, further comprising a cutting step of cutting the substrate into a predetermined dimension before the heating step.   The method for manufacturing a substrate according to claim 1, further comprising a cleaning step for cleaning the substrate between the hole forming step and the heating step. The substrate is an insulating substrate;
The manufacturing method of the board | substrate as described in any one of Claims 1-3 whose said hole is a through-hole.   The manufacturing method of the board | substrate of Claim 4 whose said insulating substrate is a prepreg formed by impregnating a glass woven fabric or a nonwoven fabric with a thermosetting resin composition, and making the said thermosetting resin composition into B stage.   The method for manufacturing a substrate according to claim 4, further comprising a filling step of filling the through hole with a conductive paste after the heating step.   The manufacturing method of the board | substrate as described in any one of Claims 4-6 which forms the said through-hole in the said insulated substrate using a laser.   The method for manufacturing a substrate according to any one of claims 4 to 7, wherein a peelable resin film is laminated on at least one surface of the insulating substrate.   The manufacturing method of the board | substrate as described in any one of Claims 5-8 which further includes the 1st heating-pressing process of heating-pressing what laminated | stacked metal foil on both surfaces of the said prepreg after the said heating process.   The method for manufacturing a substrate according to claim 9, further comprising a patterning step of patterning the metal foil after the first heating and pressing step.   A substrate obtained by the method for producing a substrate according to claim 10 is an inner layer circuit substrate, and further includes a second heating and pressing step of heating and pressing a laminate of a prepreg and a metal foil on both surfaces of the inner layer circuit substrate. A method for manufacturing a substrate.   A substrate obtained by the substrate manufacturing method according to claim 10 is used as an inner circuit board, a plurality of the inner circuit boards and prepregs are alternately laminated, and a metal foil laminated on the outermost layer is heated and pressed. The manufacturing method of a board | substrate further including the heating-pressing process of these.

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