JP2010073862A - Method for manufacturing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board in which precision of lamination by an interlayer connection means using a conductive paste is improved, and high density and excellent quality are achieved. <P>SOLUTION: In the method for manufacturing the circuit board, formation of a peeling starting part is performed during the period from the step of processing a through-hole to the step of filling conductive paste, to prevent breakage of prepreg sheet upon forming the peeling starting part, and variations in dimension of the prepreg sheet are improved. Thus, a high quality circuit board is provided of which electrical connection by an interlayer connection means with the conductive paste is stable. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a circuit board used in various electronic devices, and a release film in the process of manufacturing a multilayer circuit board or the like in which a plurality of circuit patterns are connected to inner via holes with a conductive paste. It is related with the peeling method.

  As electronic devices have become smaller and more dense in recent years, more and more circuits and components can be integrated on a circuit board on which electronic components are mounted. High density substrates have been developed.

  An example of manufacturing a conventional circuit board will be described below.

  In recent years, with the miniaturization and high density of electronic devices, there has been a strong demand for multilayer substrates not only for industrial use but also for consumer use.

  In particular, as the density of a multilayer substrate increases, circuit patterns become finer, and it is desired to reduce the thickness of the substrate together with a plurality of circuit patterns.

  In such a circuit board, it is indispensable to newly develop a connection method for connecting inner via holes between circuit patterns of multiple layers and a highly reliable structure, but a high density in which inner via holes are connected by a conductive paste. Circuit boards have been developed.

  An example of a conventional method for manufacturing a two-layer substrate with inner via hole connection using a conductive paste will be described below.

  7A to 7E are process cross-sectional views of a conventional method for manufacturing a double-sided circuit board. FIG. 8 is a plan view for explaining the formation of a peeling trigger portion, and FIG. It is peeling peeling part AA 'part sectional drawing.

  In FIG. 7, reference numeral 21 denotes a prepreg sheet, and for example, a base material made of a composite material obtained by impregnating a non-woven wholly aromatic polyamide fiber or glass cloth with a thermosetting epoxy resin is used.

  On the front and back of the prepreg sheet 21, release films 22a and 22b made of a plastic film having a release layer portion, such as polyethylene terephthalate, are bonded. Reference numeral 23 denotes a through hole filled with a conductive paste 24 made of conductive particles such as copper and epoxy resin electrically connected to metal foils 25a and 25b such as copper to be attached to the front and back of the prepreg sheet 21. Yes.

  First, as shown in FIG. 7A, release films 22a and 22b are bonded to both surfaces of a sheet prepreg sheet 21 using a roll laminating method.

  The release films 22a and 22b are used as mask films when the conductive paste 24 is filled, and become unnecessary after the conductive paste 24 is filled, and need to be peeled off.

  In the release film peeling process described later, when peeling the release films 22a and 22b from the prepreg sheet 21, it is necessary to easily hold the release films 22a and 22b and to peel the release films 22a and 22b securely. There is. For this reason, as shown in FIG. 8 and FIG. 9, after the release films 22a and 22b are bonded to both surfaces of the prepreg sheet 21 by the roll laminating method, the prepreg sheet 21 and the release film 22a, which are continuously conveyed, A jig 27 having a U-shaped cross section made of a metal steel material or the like is inserted between 22b and the release films 22a and 22b at one end of the prepreg sheet 21 are peeled off to remove unattached portions, that is, peeling trigger portions 26. Form.

  Next, as shown in FIG. 7B, a through hole 23 is formed by using a laser processing method or the like. Thereafter, as shown in FIG. 7C, the through hole 23 is electrically conductive by using a squeezing method or the like. The conductive paste 24 is filled.

  Then, as shown in FIG. 7 (d), the release film 22a, 22b, which is no longer necessary after the conductive paste 24 is filled, is used to release the release film 26 formed in FIG. 7 (a). 22a and 22b are peeled off.

  Then, as shown in FIG. 7 (e), metal foils 25a and 25b such as copper are arranged on the front and back sides of the prepreg sheet 21, and the prepreg sheet 21 and the metal foil are molded and cured by heating and pressing with a hot press. The metal foils 25a and 25b on the front and back sides are electrically connected by the conductive paste 24 filled in the through holes 23 provided at predetermined positions.

  Then, the metal foils 25a and 25b on both sides are selectively etched to form a circuit pattern (not shown) to obtain a circuit board on both sides.

  In FIG. 7, the release triggers 26 of the release films 22a and 22b are formed by bonding the release films 22a and 22b to the prepreg sheet 21 by the roll laminating method, and then continuously transporting the prepreg sheet 21 and the release film 22a. , 22b, a jig 27 having a U-shaped cross section made of a metal steel material is inserted, and the release films 22a, 22b at one end of the prepreg sheet 21 are peeled off to form a peeling trigger portion 26. .

  Although different from the case of the release films 22a and 22b used for the mask film of the conductive paste 24, the metal foils 25a and 25b are selectively used in other circuit board manufacturing processes such as circuit formation. A protective film for a photosensitive dry film used as a material for forming an etching resist during etching is also a film that becomes unnecessary after the completion of exposure and is peeled off. As a peeling method, a method (not shown) in which air is blown to a protective film scratched with a vibration pen before etching is generally used.

For example, Patent Documents 1 to 3 are known as prior art document information related to the invention of this application.
JP-A-6-268345 JP-A-8-181489 JP-A-10-303555

  However, as described above, a protective film scratched with a vibration pen, such as a method for forming a peeling trigger portion of a release film using a jig 27 and a protective film peeling method for a dry film in a circuit board manufacturing process. In the method of forming a separation trigger part by blowing air on the prepreg sheet, the prepreg sheet based on the B-stage resin, which is easy to break, is scattered when the prepreg sheet is damaged by a vibration pen or when the prepreg sheet is blown or broken. The strength of the prepreg sheet decreases as the thickness of the prepreg sheet is reduced, such as adhesion of resin components on the through-holes, causing poor connection, and without destroying the prepreg sheet. It becomes difficult to form a peeling trigger part.

  In addition, in the peeling film peeling method and circuit board manufacturing method as described above, when forming a peeling trigger portion on the release film before forming the through-hole, dimensional variation of the prepreg sheet after the release film occurs. In some cases, the metal foil pattern and the through hole filled with the conductive paste may cause a connection failure or a short circuit due to misalignment. This conventional problem will be described below with reference to the drawings.

  FIG. 10 is a plan view for explaining a problem in the conventional example, with a release film in which a release film is bonded to both surfaces of a prepreg sheet, and a release trigger part 26 is formed by peeling off the release film at one end. The distribution of the compressive stress strength of the release film with respect to the prepreg sheet 30 is shown.

  Adhesion of the release film to the prepreg sheet using a laminator is adhered to the prepreg sheet in a state where the release film is stretched by the tension to the release film and the temperature / pressure of the laminator. Therefore, although the release film compressive stress 28 is applied to the release film-attached prepreg sheet 30, the release trigger portion 26 from which a part of the release film has been peeled is released from the release film compressive stress. Thus, it becomes a portion where there is no compressive stress or a portion that remains slightly. In this state, the through holes are processed and filled with the conductive paste, and then the release film is peeled off.

  When the release film is peeled off from the prepreg sheet 30 with the release film, the prepreg sheet from which the release stress of the release film is released is stretched on the side opposite to the compression stress 28.

  On the other hand, since the compressive stress is released at the point where the peeling trigger part 26 is formed, the compressive stress is released at the time when the peeling trigger part 26 is formed.

  As a result, the position of the through-hole formed in the prepreg sheet 30 with a release film is shifted, causing a connection resistance failure or a short circuit due to the position shift.

  The present invention provides a circuit board manufacturing method in which a through hole formed in a prepreg sheet with a release film does not cause displacement even after the release film is peeled off. The present invention also provides an apparatus and a method that do not cause substrate destruction even in the case of a prepreg sheet having a thin plate thickness in the formation of the peeling trigger portion of the release film.

  The method for manufacturing a circuit board according to the present invention includes a step of adhering a release film to the entire front and back surfaces including an end portion of a prepreg sheet, a step of forming a through hole at a predetermined position of the prepreg sheet, A step of forming a peeling trigger portion on the surface, a step of filling the through hole with a conductive paste, a step of peeling the release film from the prepreg sheet starting from the peeling trigger portion, and on the front and back of the prepreg sheet And a step of heat-pressing the metal foil.

  Thereby, the dimensional dispersion of the prepreg sheet can be improved, and the production of a high-definition circuit board can be easily performed.

  In particular, the step of forming the peeling trigger portion at the end portion of the prepreg sheet includes a first side portion provided with a peeling prevention portion on the end surface and one end in contact with or close to the first side portion and an air intrusion portion at the other end. A peeling trigger formation in which an upper member and a lower member composed of a second side portion provided are arranged in plane symmetry with each other, and the peeling prevention portions of the upper member and the lower member are arranged to face each other at a constant interval. The circuit board of the present invention can be easily manufactured by sandwiching the end portion of the prepreg sheet with the peeling prevention portion of the jig and blowing air to the end portion of the prepreg sheet through the air intrusion portion. In addition, destruction of the prepreg sheet at the time of forming the peeling trigger portion can also be prevented.

  The method of manufacturing a circuit board according to the present invention makes it possible to form a peeling trigger portion from the through hole processing to the conductive paste filling step, and prevents the prepreg sheet from being destroyed during the formation of the peeling trigger portion. Improve sheet dimensional variation, provide a high-quality circuit board with stable electrical connection by means of interlayer connection using conductive paste, and also break the prepreg sheet during the formation of peeling triggers in the manufacturing process It can also be prevented.

(Embodiment)
A peeling trigger forming apparatus, a peeling trigger forming method, and a circuit board manufacturing method according to an embodiment of the present invention will be described with reference to FIGS.

  First, a method for manufacturing a double-sided circuit board that will be an inner layer board of an inner via hole connection multilayer board using a conductive paste will be described.

  1A to 1F are process cross-sectional views of a method for manufacturing a double-sided circuit board according to the present invention.

  In FIG. 1, reference numeral 1 denotes a prepreg sheet, for example, using a base material made of a composite material obtained by impregnating a non-woven wholly aromatic polyamide fiber or glass cloth with a thermosetting epoxy resin.

  Plastic films having release layer portions, for example, release films 2a and 2b made of polyethylene terephthalate or the like are bonded to the front and back of the prepreg sheet 1 using a laminating apparatus.

  Reference numeral 3 denotes a through hole, which is filled with a conductive paste 4 that is electrically connected to metal foils 5 a and 5 b such as copper attached to the front and back of the prepreg sheet 1. The conductive paste 4 is obtained by kneading metal particles such as copper in a thermosetting resin such as an epoxy resin in order to impart conductivity.

  First, as shown in FIG. 1 (a), as a manufacturing material provided with a release film, release films 2a and 2b having a width wider than that of the prepreg sheet 1 are laminated on the entire front and back surfaces including the end of the prepreg sheet 1. After continuous bonding using, cut into individual pieces (sheets). At this time, it is desirable that the release films 2 a and 2 b protrude from both ends of the prepreg sheet 1 and be bonded. This is because the formation of the peeling trigger portion described later can be performed smoothly.

  Further, conventionally, a peeling trigger portion was formed at the end portion of the prepreg sheet in the stage immediately after this step, but in the present invention, the release film is adhered to the entire front and back surfaces including the end portion of the prepreg sheet 1, A peeling trigger part is formed after the formation of the through hole in the next step.

  In the embodiment of the present invention, a laminating apparatus is used for bonding the release films 2a and 2b to the front and back of the prepreg sheet 1. However, a flat plate vacuum laminator or a hot press may be used.

  Next, as shown in FIG. 1B, a through hole 3 is formed using a laser processing method or the like.

  Next, as shown in FIG.1 (c), the release films 2a and 2b of the one side end of the prepreg sheet 1 are peeled, and the peeling trigger parts 6a and 6b are formed. The peeling trigger portions 6 a and 6 b are peeled off from the prepreg sheet 1 by partly releasing the release films 2 a and 2 b so that the release films 2 a and 2 b are slightly lifted from the prepreg sheet 1.

  And as shown in FIG.1 (d), the conductive paste 4 is filled into the through-hole 3 of the prepreg sheet 1 using a well-known printing method.

  Next, as shown in FIG. 1 (e), the release films 2 a and 2 b are peeled from the entire surface of the prepreg sheet 1 with the peeling trigger portion 6 as a starting point. After the release films 2a and 2b are peeled off, the conductive paste 4 protrudes by the thickness of the release films 2a and 2b. The release films 2a and 2b can be peeled simultaneously or on both sides using a suction pad, a chuck, an adhesive sheet, etc. using the release triggers 6a and 6b of the release films 2a and 2b formed in FIG. It peels off every time (not shown).

  Since the release trigger portions 6a and 6b are formed on the prepreg sheet 1, it is easy to adsorb, chuck, and bond only the release films 2a and 2b, and the release films 2a and 2b can be stably detached from the prepreg sheet 1. Can be peeled off.

  Next, as shown in FIG.1 (f), metal foil 5a, 5b, such as copper, is arrange | positioned at the front and back of the prepreg sheet 1, and it is made to harden | cure by heating and pressurizing with a hot press, and the prepreg sheet 1 and metal The foils 5a and 5b are bonded, and the conductive paste 4 is compressed, so that the front and back metal foils 5a and 5b are electrically connected by the conductive paste 4 filled in the through-holes 3 of the product provided at predetermined positions. The Although not shown in FIG. 1, the metal foils 5a and 5b are then selectively etched to form a circuit pattern, whereby a two-layer circuit board is obtained.

  Here, the detail of the formation method of the peeling trigger part 6 in the process of above-mentioned FIG.1 (c) is demonstrated below.

  First, the configuration of the peeling trigger forming apparatus in the present embodiment will be described.

  As shown in FIG. 2, the outline of the apparatus includes a peeling trigger forming jig 7, an air nozzle 8, and supply means (not shown) such as a supply pump for supplying air 9 to the air nozzle.

  As shown in the cross-sectional view of FIG. 3, the peeling trigger forming jig 7 has a first side portion 13 having a peeling prevention portion 12 on the end surface and one end in contact with or close to the first side portion, and air intrusion into the other end. As shown in the drawing, an upper member 15a composed of a second side portion 14 provided with a portion 11 and a lower member 15b having the same configuration as the upper member 15a are arranged in plane symmetry with each other. The peeling preventing portions 12 of the member 15a and the lower member 15b are arranged to face each other at regular intervals.

  This fixed interval means that the prepreg sheet 1 in which the release films 2a and 2b are bonded to the front and back surfaces as the manufacturing material provided with the release film as shown in the figure is sandwiched between the upper and lower peeling prevention portions 12. The interval is set to be possible, and is preferably about the total thickness between the release films 2a and 2b and the prepreg sheet 1.

  Further, the air intrusion portion 11 is structured to be inclined at a predetermined angle from the extreme end portion of the second side portion 14 toward the release prevention portion 12 on the first side, so that air blown from the air nozzle 8 is blown. 9 can be effectively taken into the peeling trigger forming jig 7.

  The air nozzle 8 can also be provided with a vertically movable mechanism. Thereby, the supply of air to the release film becomes more reliable, and the formation of the peeling trigger is further stabilized.

  Further, the air nozzle 8 or the peeling trigger forming jig 7 has a horizontal movable mechanism, and after the predetermined position of the end portion of the prepreg sheet to which the release film is adhered is clamped, the air nozzle or the prepreg sheet is moved. Thus, the peeling trigger portion can be stably formed on the entire surface of one side.

  The second side portion 14 is preferably provided with a gap portion 16 except for the air intrusion portion 11. As shown in FIG. 3, the gap portion 16 is to provide a space at a constant interval between the prepreg sheet to which a release film is bonded as a manufacturing material and the second side portion 14. By providing, it has the effect of preventing breakage of the manufacturing material.

  In particular, it is possible to adjust the space of the gap portion 16 by forming the second side portion 14 so as to move up and down while being in contact with or close to the first side portion 13, and at the same time, forming a peeling trigger. The amount of air flowing into the jig 7 can be adjusted, and a peeling trigger portion can be formed according to the mechanical strength, thickness, etc. of the manufacturing material.

  In addition, when the space between the manufacturing material and the second side portion 14 is set to an optimum value and the space of the gap portion 16 can be fixed, the first side portion and the second side portion are formed as one member. The cross-sectional shape can be substantially L-shaped. Thereby, the structure of the peeling trigger formation jig | tool 7 can be simplified and the manufacturing cost of an apparatus can be reduced.

  The intent of making the cross-sectional shape substantially L-shaped is equivalent to the peeling prevention portion 12 on the first side and the air intrusion portion 11 on the second side, including the case where the shape is L-shaped in English letters. If it has a structure and has the same function, the case where the cross-sectional shape is similar to an L-shape is included.

  Next, a peeling trigger forming method using the above-described peeling trigger forming apparatus will be described.

  First, an end portion of a prepreg sheet 1 as a manufacturing material having a release film is sandwiched by a peeling prevention portion 12 of a peeling trigger forming jig 7 in a peeling trigger forming device, and air is passed from an air nozzle 8 to an air intrusion portion 11. 9 is sprayed to form the peeling trigger portion 6 at the end portion of the prepreg sheet 1.

  As shown in FIG. 2, the peeling trigger portion 6 is formed by supplying air 9 from an air nozzle 8 having a diameter of 2 mm while holding the prepreg sheet 1 to which the release films 2 a and 2 b are bonded with a peeling trigger forming jig 7. Move while spraying and peel. FIG. 3 shows a cross section of the end portion of the prepreg sheet 1 in this state.

  As shown in FIG. 3, the upper and lower peeling prevention portions 12 sandwich the prepreg sheet 1, and this structure allows the peeling prevention portion 12 to be other than the peeling trigger portion 6 when forming the peeling trigger portion 6. This also has a function of preventing the release films 2a and 2b in the above part from peeling off.

  Moreover, since the air intrusion part 11 is inclined, the air 9 blown from the air nozzle 8 is guided to the release films 2a and 2b bonded to the front and back of the prepreg sheet 1, and the air is stably supplied. It can spray on the edge part of the prepreg sheet 1.

  The release films 2a and 2b are bonded to the release films 2a and 2b protruding from the end face of the prepreg sheet 1 in the process of FIG. 1A described above. For this reason, as shown in FIG. 4, the flow of the air 9 blown from the air nozzle 8 is supplied between the release films 2a and 2b, and the protruding part is peeled off from the surface of the prepreg sheet 1 to the outside. Arises. By this action, the release film is easily peeled off, and the release films 2a and 2b can be peeled stably.

  Further, a gap portion 16 is provided between the release films 2 a and 2 b and the second side portion 14 of the peeling trigger forming jig 7. Due to the presence of the gap portion 16, the air 9 is supplied to the release films 2 a and 2 b, and the prepreg sheet 1 can be prevented from being damaged when the prepreg sheet 1 vibrates up and down by the flow of the air 9.

  Since the gap portion 16 varies depending on the mechanical strength of the prepreg sheet 1, it may be set to a value that can prevent the prepreg sheet 1 to be used from being damaged.

  The prepreg sheet 1 used in the examples was 80 μm thick, and in this case, the gap was 1 mm.

  Further, as shown in FIG. 5, the air supply can be increased by arranging a plurality of prepreg sheet protection spacers 17 in the gap portion 16 on the second side portion 14 at intervals.

  As a result, the formation of the release trigger portions 6a and 6b of the release films 2a and 2b is made more stable, and in addition, the prepreg sheet protection spacer 17 is provided to prevent the prepreg sheet from being bent or broken. It can also be prevented.

  The height of the prepreg sheet protection spacer 17 is made lower than the height of the space of the gap portion 16, so that air can be smoothly supplied over the entire area of the separation trigger forming jig 7.

  In the above-described embodiment, an example in which the peeling trigger portion 6 is formed on the entire surface of one side of the manufacturing material has been shown. However, as another embodiment, as shown in FIG. 6, the peeling trigger portion 6 is a prepreg with a release film. It is also possible to form the sheet 10 at a predetermined position in at least one corner.

  As shown in FIG. 6, the peeling trigger forming apparatus in this example is composed of a first air intrusion portion 11a and a second air intrusion portion 11b, each of which has an air intrusion portion composed of two sides and whose intersections form a right angle with each other. Thus, the air nozzle is composed of a first air nozzle 8a and a second air nozzle 8b that blow air on each of the first air intrusion portion 11a and the second air intrusion portion 11b.

  Using this peeling trigger forming device, the corner portion of the prepreg sheet 1 with a release film as a manufacturing material is sandwiched between the front and back by a peeling trigger forming jig 7, and the first air intrusion portion 11a and the second air intrusion are held. Air is blown from the first air nozzle 8a and the second air nozzle 8b arranged with respect to the two sides of the portion 11b to form a peeling trigger portion at the corner portion of the prepreg sheet 1.

  In this case, it is desirable that the air nozzles 8a and 8b arranged with respect to the air intrusion portions 11a and 11b on the two sides include a vertically movable mechanism. With this configuration, when the release film on one side of the peeling trigger portions 6 formed on the two sides of the corner portion of the prepreg sheet 1 is peeled off quickly and turned up, it can be separated by using that as a starting point. The release film on the side can be easily peeled off. As a result, it is possible to stably form the release trigger portion of the release film having a predetermined shape at the corner portion of the prepreg sheet with the release film.

  The inventor made 500 double-layer substrates using the circuit board manufacturing method in the present embodiment, and formed a peeling trigger portion on the entire surface of one side of the prepreg sheet having a release film adhered to the front and back. In the formation of the peeling trigger part, there was no destruction of the prepreg sheet, and a desired peeling trigger part was formed at a predetermined position.

  In addition, by forming the peeling trigger portion after filling the paste after forming the through hole, the compressive stress of the release film adhered to the front and back of the prepreg sheet becomes uniform at the time of forming the through hole. In the conventional example, the length is 400 mm. In contrast, it was confirmed that there was no difference between the peeling trigger portion where a difference of about 50 μm had occurred and the portion other than the peeling trigger, and the positional accuracy of the through hole was improved.

  In the present embodiment, a method for manufacturing a two-layer circuit board is shown. However, the completed two-layer circuit board is used as an inner layer substrate, and the prepreg sheet and the metal foil prepared in the present invention are positioned and arranged on the front and back sides, Arbitrary multilayer substrates can be obtained by repeating pressing and circuit formation.

  In the embodiment, the prepreg sheet and the metal foil are arranged on the front and back sides of the circuit board. However, the effects of the present invention can be obtained by arranging the circuit board on the front and back sides of the prepreg sheet.

  As described above, according to the release film peeling trigger forming method and the circuit board manufacturing method of the present invention, the release film bonded to both surfaces of the prepreg sheet is peeled off in a process in which the dimensions of the prepreg sheet are stable. Since the portion can be formed, the matching between the through hole filled with the conductive paste and the metal foil pattern is excellent, and the electrical connection by the interlayer connection means of the conductive paste can be stably performed with high quality.

  As a result, a high-quality and high-density circuit board can be provided, and the industrial applicability of the present invention can be said to be great.

Sectional drawing which shows the manufacturing process of the circuit board in embodiment of this invention The figure which shows the outline | summary of the peeling trigger formation apparatus in the embodiment Sectional drawing which shows the peeling trigger formation apparatus in the embodiment Sectional drawing which shows the formation method of the peeling trigger in the same embodiment The perspective view which shows the peeling trigger jig in the same embodiment The figure which shows the outline | summary of the peeling trigger formation apparatus in the embodiment Sectional drawing which shows the manufacturing process of the circuit board in a prior art example Plan view for explaining a method of forming a peeling trigger portion in a conventional example Sectional drawing which shows the detail of the peeling trigger part in a prior art example The top view for demonstrating the subject in a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg sheet 2a, 2b Release film 3 Through-hole 4 Conductive paste 5a, 5b Metal foil 6a, 6b Peeling trigger part 7 Peeling trigger formation jig 8, 8a, 8b Air nozzle 9 Air 10 Prepreg sheet with a release film 11 , 11a, 11b Air intrusion part 12 Peeling prevention part 13 First side part 14 Second side part 15a Upper member 15b Lower side member 16 Gap part 17 Pre-preg sheet protection spacer

Claims (4)

A step of adhering a release film to the entire front and back surfaces including the end portion of the prepreg sheet, a step of forming a through hole at a predetermined position of the prepreg sheet, a step of forming a peeling trigger portion at the end portion of the prepreg sheet, A step of filling the through holes with a conductive paste, a step of peeling the release film from the prepreg sheet starting from the peeling trigger portion, and placing metal foil on the front and back of the prepreg sheet, and then hot pressing A circuit board manufacturing method comprising the steps of: 2. The circuit board according to claim 1, wherein the step of adhering the release film to the entire front and back surfaces including the end portion of the prepreg sheet is such that the release film protrudes outward from the end surface of the prepreg sheet. Manufacturing method. The method for manufacturing a circuit board according to claim 1, wherein the end portion of the prepreg sheet is a corner portion of the prepreg sheet. The step of forming the peeling trigger portion at the end of the prepreg sheet is as follows:
An upper member and a lower member, each of which includes a first side portion provided with a separation preventing portion on an end surface and a second side portion having one end in contact with or close to the first side portion and an air intrusion portion at the other end. Sandwiching the end portion of the prepreg sheet with the peeling preventing portion of the peeling trigger forming jig, which is arranged symmetrically with respect to each other, and the peeling preventing portions of the upper member and the lower member are arranged to face each other at regular intervals, The method for manufacturing a circuit board according to claim 1, wherein air is blown to an end portion of the prepreg sheet through the air intrusion portion.

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