Printed wiring board and wiring trimming method

Abstract

To provide a printed wiring board and a wiring trimming method capable of easily cutting a wiring.SOLUTION: On a second main surface 1b of a printed wiring board 1 in which a plurality of base materials 5 are laminated, a cut hole 11 is formed from the second main surface 1a toward a first main surface 1b side in such a manner that a thin part 12 thinner than the thickness of the printed wiring board 1 is left on the first main surface 1a side. The thin portion 12 formed such that the glass fibers 9 do not remain includes a first thin portion 12a, a second thin portion 12b, and a third thin portion 12c. The first wiring 21a is arranged so as to cross the first thin portion 12a, the second wiring 21b is arranged so as to cross the second thin portion 12b, and the third wiring 21c is arranged so as to cross the third thin portion 12c.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a printed wiring board and a wiring trimming method. [Background technology]

[0002] Before shipping an assembled circuit board product in which electrical components are mounted on a printed wiring board, or during product assembly when incorporating a printed wiring board into a pre-existing electrical product, a process known as trimming is performed on the printed wiring board to set the circuit's function, mode, or product-specific state. For example, a circuit may be selected to correspond to a power supply voltage appropriate for the overseas shipping destination. Or, a unique address value may be set for each individual printed wiring board.

[0003] In conventional printed wiring boards, jumper pins or switch components (bit switches, rotary switches, etc.) are pre-mounted on the printed wiring board. The above-mentioned settings are made by switching the circuit depending on the number of pins or the position of the switch.

[0004] Once set, this setting is rarely changed during the life of the product. Furthermore, mechanical components such as switches tend to be more expensive than other electrical components. Therefore, from the perspective of the product purchaser, this meant that costs were being spent on parts that the product user would not use, which was undesirable from both an economic and environmental perspective.

[0005] To improve this situation, Patent Document 1 proposes a printed wiring board provided with a plurality of cut sections, each including a portion of a wiring pattern. The cut sections on the printed wiring board are provided with a cutting slit or the like, and an operator can switch the circuit by cutting one of the plurality of cut sections from the corresponding slit or the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 06-23271 Summary of the Invention [Problem to be solved by the invention]

[0007] Among printed wiring boards, there is a rigid type laminated printed wiring board that uses a composite material containing a resin such as epoxy resin and glass fiber. This laminated printed wiring board is called "FR-4." In this laminated printed wiring board, the base material that constitutes the laminated printed wiring board itself has strong rigidity. Therefore, cutting the laminated printed wiring board to cut the wiring can be difficult for workers.

[0008] The present disclosure has been made to solve such problems, and one object is to provide a printed wiring board in which wiring can be easily cut, and another object is to provide a wiring trimming method in which wiring can be easily cut. [Means for solving the problem]

[0009] A printed wiring board according to the present disclosure includes a substrate and one or more traces. The substrate includes glass fiber, has opposing first and second main surfaces, and has a first thickness. The one or more traces are formed on the first main surface of the substrate, and trimming is performed. The substrate includes one or more thin-walled portions formed on the first main surface, corresponding to the one or more traces, that are thinner than the first thickness, and do not include glass fiber. The one or more traces are formed so as to cross the corresponding thin-walled portions.

[0010] One interconnect trimming method according to the present disclosure is a method for trimming one or more interconnects formed on a first main surface of a substrate containing glass fiber, having opposing first and second main surfaces and a first thickness. The substrate has one or more thinned portions corresponding to the one or more interconnects, each of which is thinner than the first thickness and does not contain glass fiber. The one or more interconnects are formed so as to cross the corresponding thinned portions. A process is performed to trim the interconnects to be trimmed among the one or more interconnects.

[0011] Another wire trimming method according to the present disclosure is a wire trimming method for trimming one or more wires formed on a first main surface of a substrate containing glass fiber and having opposing first and second main surfaces, the method comprising: cutting, by router processing, the wires to be trimmed together with the substrate from an end face of the substrate. [Effects of the Invention]

[0012] In the printed wiring board according to the present disclosure, the substrate includes one or more thinned portions that are thinner than the first thickness and do not contain glass fibers, and one or more traces to be trimmed are formed to cross the corresponding thinned portions, which makes it easy to cut the traces.

[0013] In one wire trimming method according to the present disclosure, one or more thinned portions that are thinner than a first thickness and do not contain glass fibers are formed on a substrate. Trimming of the wires to be trimmed is performed among the one or more wires that are formed to cross the corresponding thinned portions, thereby facilitating trimming.

[0014] Another wiring trimming method according to the present disclosure includes a process of cutting one or more wirings to be trimmed together with the substrate from the edge face of the substrate using a router, thereby making trimming easy. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a plan view of a printed wiring board according to a first embodiment. [Figure 2] 2 is a cross-sectional view of the printed wiring board taken along line II-II in FIG. 1 in the embodiment. [Figure 3] FIG. 3 is a partial cross-sectional perspective view of the printed wiring board shown in FIGS. 1 and 2 in the embodiment. [Figure 4] FIG. 10 is a plan view showing a state of the printed wiring board after trimming in the embodiment. [Figure 5] 5 is a cross-sectional view of the printed wiring board taken along the cross-sectional line VV shown in FIG. 4 in the embodiment. [Figure 6] FIG. 6 is a partial cross-sectional perspective view of the printed wiring board shown in FIGS. 4 and 5 in the embodiment. [Figure 7] FIG. 2 is a partial cross-sectional view showing an example of a usage mode of a printed wiring board after trimming in the embodiment. [Figure 8] FIG. 10 is a plan view of a printed wiring board according to a second embodiment. [Figure 9] 9 is a cross-sectional view of the printed wiring board taken along the cross-sectional line IX-IX shown in FIG. 8 in the embodiment. [Figure 10] FIG. 10 is a plan view showing a state of the printed wiring board after trimming in the embodiment. [Figure 11] 11 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XI-XI shown in FIG. 10 in the embodiment. [Figure 12] FIG. 10 is a plan view of a printed wiring board according to a modified example of the embodiment. [Figure 13] 13 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XIII-XIII shown in FIG. 12 in the embodiment. [Figure 14] FIG. 10 is a plan view showing a state of a printed wiring board according to a modified example after trimming has been performed in the embodiment. [Figure 15]15 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XV-XV shown in FIG. 14 in the embodiment. [Figure 16] FIG. 10 is a plan view of a printed wiring board according to a third embodiment. [Figure 17] 17 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XVII-XVII shown in FIG. 16 in the embodiment. [Figure 18] FIG. 10 is a plan view showing a state of the printed wiring board after trimming in the embodiment. [Figure 19] 19 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XIX-XIX shown in FIG. 18 in the embodiment. [Figure 20] FIG. 10 is a plan view of a printed wiring board according to a fourth embodiment. [Figure 21] 21 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XXI-XXI shown in FIG. 20 in the embodiment. [Figure 22] FIG. 10 is a plan view showing a state of the printed wiring board after trimming in the embodiment. [Figure 23] 23 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XXIII-XXIII shown in FIG. 22 in the embodiment. [Figure 24] FIG. 10 is a plan view of a printed wiring board according to a fifth embodiment. [Figure 25] 25 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XXV-XXV shown in FIG. 24 in the embodiment. [Figure 26] FIG. 2 is a circuit diagram showing an example of a power supply circuit including a fuse formed on a printed wiring board in the embodiment. [Figure 27] FIG. 10 is a plan view showing a state of the printed wiring board after the fuse has been blown in the embodiment. [Figure 28] FIG. 28 is a cross-sectional view of the printed wiring board taken along the cross-sectional line XXVIII-XXVIII shown in FIG. 27 in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiment 1 A description will be given of a printed wiring board and a wire trimming method according to embodiment 1. First, an example of a printed wiring board will be described.

[0017] 1, 2, and 3, printed wiring board 1 is a printed wiring board 1 formed by laminating a plurality of base materials 5 as substrates. Here, an example is given of printed wiring board 1 in which three base materials 5, a first base material 5a, a second base material 5b, and a third base material 5c, are laminated, and four layers of wiring 21 are formed. Printed wiring board 1 has a first thickness.

[0018] The printed wiring board 1 may be a printed wiring board 1 made of a single layer of substrate 5, with a single layer of wiring 21 formed on one surface of the substrate 5. Alternatively, the printed wiring board 1 may be a printed wiring board 1 having two layers of wiring 21, with wiring 21 formed on both one surface and the other surface of the single layer of substrate 5. Furthermore, by stacking substrates 5, the printed wiring board 1 may have, for example, five or more layers of wiring 21 (neither is shown).

[0019] Each base material 5 is made of a woven fabric of glass fiber 9 impregnated with resin 7 such as epoxy resin. A copper foil film (not shown) that serves as wiring and is attached to the surface of base material 5 is not in contact with glass fiber 9. Therefore, a high proportion of resin 7 occupies the area near wiring 21 that is formed by etching the copper foil film.

[0020] Wiring 21 for cutting the circuit, i.e., wiring 21 to be trimmed, is formed on first main surface 1a of the lowermost layer of printed wiring board 1. Wiring 21 includes first wiring 21a, second wiring 21b, and third wiring 21c.

[0021] A machined hole 11 is formed as an opening on the second main surface 1b of the printed wiring board 1, extending from the second main surface 1b toward the first main surface 1a. In the manufacturing process of the printed wiring board 1, a cylindrical hole is the type of hole that can be formed most efficiently with a small area. The machined hole 11 is formed at a position away from the end surface 3a of the printed wiring board 1.

[0022] The processing machine for forming the cut hole 11 may be, for example, a laser processing machine, a drill processing machine, or a router processing machine. Generally, the laser processing machine and the drill processing machine are used to form, for example, inner vias or through holes in a printed wiring board. The router processing machine is used, for example, to cut the outer shape of a printed wiring board.

[0023] By using such a processing machine, it is possible to form cylindrical cut hole 11. Note that the shape of cut hole 11 is not limited to a cylindrical shape. For example, cut hole 11 may be an elliptical cylinder or a rectangular cylinder.

[0024] The cut hole 11 is formed from the second main surface 1b toward the first main surface 1a in such a manner that a thin portion 12 thinner than the thickness of the printed wiring board 1 is left on the first main surface 1a side. The cut hole 11 is formed at a position away from the end face 3a of the printed wiring board 1. The thin portion 12 is located at the bottom of the cut hole 11. The cut hole 11 is formed so that no glass fiber 9 remains in the thin portion 12. The resin 7 is substantially located in the thin portion 12.

[0025] The cut holes 11 include a first cut hole 11a, a second cut hole 11b, and a third cut hole 11c. The thin-walled portion 12 includes a first thin-walled portion 12a, a second thin-walled portion 12b, and a third thin-walled portion 12c. The first wiring 21a is arranged to cross the first thin-walled portion 12a. The second wiring 21b is arranged to cross the second thin-walled portion 12b. The third wiring 21c is arranged to cross the third thin-walled portion 12c.

[0026] Thin portion 12 may be formed so that the combined thickness T of thin portion 12 and wiring 21 is, for example, about 50 μm to 150 μm. More preferably, if thickness T is about 100 μm, thin portion 12 can be easily cut together with wiring 21. Furthermore, a minimum level of rigidity can be ensured for thin portion 12.

[0027] The wiring 21 may be coated by, for example, plating, resist, or silk printing. The wiring 21 and the like may be formed so that the thickness T including the coating is about 50 μm to 150 μm.

[0028] After the cut holes 11 are formed in the printed wiring board 1, assembly is performed to mount electrical components on the printed wiring board 1. During this assembly, the cut holes 11 are not particularly involved and remain open.

[0029] By placing printed wiring board 1 in a reflow furnace, solder is supplied only to the pads of the components in the process of soldering components to printed wiring board 1. In addition, in the soldering process, a jet of solder is sprayed onto first main surface 1a of printed wiring board 1, so the solder does not get into cut holes 11.

[0030] Furthermore, when a jet of solder is sprayed from the second main surface 1b side of the printed wiring board 1, the solder does not settle and the cut hole 11 is not filled with solder because no conductor such as metal is exposed on the inner wall of the cut hole 11.

[0031] In the printed wiring board 1, a multi-bit switch is formed by providing a plurality of cut holes 11 and arranging wires 21 so as to cross each of the thin-walled portions 12 located at the bottom of the plurality of cut holes 11. In the above-described printed wiring board 1, three cut holes 11 and three wires 21 are provided. This printed wiring board 1 has the same function as a three-bit on / off switch. In other words, the printed wiring board 1 has a switch that can set eight patterns (2 x 2 x 2) only once.

[0032] The cut holes 11 do not have to be arranged along a straight line. They may be formed in a position where they can be arranged efficiently together with the wiring 21 arranged on the first main surface 1a of the printed wiring board 1. In this case, it is desirable to mark the bit number, switch name, etc. indicating the switch attribute on the printed wiring board 1 by silk printing or the like. Which wiring 21 to turn off can be selected by checking the attribute marking.

[0033] Next, an example of a wire trimming method for trimming wires 21 on the above-described printed wiring board 1 will be described. Trimming of wires 21 is performed by breaking through thin-walled portion 12 across which desired wires 21 cross. As shown in Figures 4, 5, and 6, here, an example will be given in which first wires 21a crossing first thin-walled portion 12a are cut.

[0034] To break through the thin-walled portion 12, a rod-shaped tool (not shown) having a diameter smaller than the opening diameter of the cut hole 11 is used. The rod-shaped tool is inserted into the first cut hole 11a and presses against the first thin-walled portion 12a, thereby breaking through the first thin-walled portion 12a. By breaking through the first thin-walled portion 12a, the first wiring 21a arranged to cross the first thin-walled portion 12a is cut. A tool with a pointed tip that can apply a concentrated pressure to one point or in a straight line is desirable as the tool used to cut the wiring 21.

[0035] The diameter of cut hole 11 is preferably about 1.7 mm to 2.5 mm. If the diameter of cut hole 11 is 2.1 mm, cut hole 11 serves as a guide hole for a tool having a diameter of 2.0 mm or less, and the vicinity of the center of first thin-walled portion 12a located at the bottom of cut hole 11 can be relatively easily broken through with the tool.

[0036] By breaking through the first thin portion 12a, a cut portion 15 is formed in the first wiring 21a on the first main surface 1a side of the printed wiring board 1, with the first thin portion 12a curled outward. Unless a force is applied to return the curled first thin portion 12a to its original state, the first thin portion 12a will remain curled. Therefore, the first wiring 21a will not short-circuit. Furthermore, no cutting waste will be generated.

[0037] In order to prevent the first thin-walled portion 12a that has curled outward from being accidentally restored to its original shape, the first cut hole 11a may be filled with an insulating filler such as a resin adhesive. Also, an insulating pin made of an insulating material such as plastic may be inserted into the first cut hole 11a.

[0038] 7, an insulating pin 53 is prepared that is longer than the thickness of printed wiring board 1 and has a diameter corresponding to the diameter of cut hole 11. By inserting insulating pin 53 into first cut hole 11a, the tip of insulating pin 53 is inserted into cut portion 15, and first thin-walled portion 12a that has curled up outward can be effectively prevented from returning to its original shape.

[0039] In the above-described printed wiring board 1, a circuit is configured that opens the cut first wiring 21a and shorts the uncut second wiring 21b and third wiring 21c, thereby functioning as a one-time switch. By providing printed wiring board 1 with a circuit that obtains a logical value (0 or 1) corresponding to an open or short circuit, this can be made to function as a one-time bit switch, and a function-, mode-, and product-specific state of the circuit based on a truth table can be set.

[0040] As shown in FIG. 7, it is desirable to insert plastic pins 51 into the corresponding second cut holes 11b for the uncut second wirings 21b, etc. The color of the plastic pins 51 is desirably different from the color of the insulating pins 53. By using such plastic pins 51 and insulating pins 53, it is possible to easily determine the state of the wirings 21 (short-circuited state or open state). In addition, the thin-walled portion 12 can be protected.

[0041] Embodiment 2 A description will be given of a printed wiring board and a wire trimming method according to embodiment 2. First, an example of a printed wiring board will be described.

[0042] 8 and 9, a cut hole 11 serving as an opening is formed in the second main surface 1b of the printed wiring board 1, extending from the second main surface 1b toward the first main surface 1a. The cut hole 11 is formed from the end surface 3a of the printed wiring board 1 toward the inner region of the printed wiring board 1. Note that the rest of the configuration is the same as that of the printed wiring board 1 shown in FIGS. 1 to 3, and therefore the same members are denoted by the same reference numerals, and their description will not be repeated unless necessary.

[0043] Next, an example of a wire trimming method for trimming wires 21 on the above-described printed wiring board 1 will be described. Trimming of wires 21 is performed by breaking through thin-walled portion 12 across which desired wires 21 cross. As shown in Figures 10 and 11, here, an example will be given in which first wires 21a crossing first thin-walled portion 12a are cut.

[0044] In the printed wiring board 1, the cut hole 11 is formed from the end surface 3a of the printed wiring board 1 toward the inner region of the printed wiring board 1. Therefore, the first thin portion 12a is exposed at the end surface 3a. Because the first thin portion 12a is exposed at the end surface 3a of the printed wiring board 1, a blade such as nippers or scissors can be used as a tool to cut the first wiring 21a together with the first thin portion 12a. The first thin portion 12a is clamped from the end surface 3a of the printed wiring board 1 with nippers or the like, and the first thin portion 12a is cut together with the first wiring 21a. A cut portion 15 is formed in the first wiring 21a. In this manner, the wiring 21 is trimmed.

[0045] In the above-described printed wiring board 1, the cut holes 11 are formed from the end surface 3a of the printed wiring board 1 toward the inner region of the printed wiring board 1, so that the first thin-walled portions 12a are exposed at the end surface 3a. This makes it easy to trim the wiring 21 using a cutting tool such as nippers or scissors.

[0046] (Variation) In the above-mentioned printed wiring board 1, board outline data that includes data on the area where the cutting hole 11 will be formed may be acquired in advance as the board outline data that will ultimately be cut, and the cutting hole 11 may be formed based on that board outline data.

[0047] As shown in Figures 12 and 13, here we will take as an example a case where first wiring 21a is cut. In this case, board outline data including data on the area where first cutting hole 11a is to be formed is set in advance as board outline data. Next, as shown in Figures 14 and 15, based on the board outline data, a U-shaped first cutting hole 11a is formed from end surface 3a of printed wiring board 1 toward the inside of printed wiring board 1 by router processing. By forming first cutting hole 11a, first wiring 21a is cut.

[0048] In this wire trimming method, data on the area where cutting holes 11 are to be formed is included in the board outline data that will ultimately be cut as the printed wiring board 1, so that the wires 21 to be trimmed are cut. This allows the first cutting holes 11a to be formed simultaneously when router processing is performed on the printed wiring board 1, and the first wires 21a can be easily cut.

[0049] Embodiment 3 A description will be given of a printed wiring board and a wire trimming method according to embodiment 3. First, an example of a printed wiring board will be described.

[0050] 16 and 17, in printed wiring board 1, the patterns (orientations) of wiring 21 crossing thin-walled portions 12 located at the bottom of cut holes 11 are different from one another. If wiring 21 crossing one thin-walled portion 12 is considered to be one switch, the pattern of wiring 21 is different for each switch.

[0051] First wiring 21a crossing first thin portion 12a extends at an angle of -60°, with clockwise rotation being positive, relative to the direction in which end face 3b of printed wiring board 1 extends. Second wiring 21b crossing second thin portion 12b extends at an angle of +60° relative to the direction in which end face 3b of printed wiring board 1 extends. Third wiring 21c crossing third thin portion 12c extends in the direction in which end face 3b of printed wiring board 1 extends.

[0052] According to the positional relationship between the hour and minute hands of a clock, the first wiring 21a extends in the direction of 4 o'clock to 10 o'clock, the second wiring 21b extends in the direction of 2 o'clock to 8 o'clock, and the third wiring 21c extends in the direction of 12 o'clock to 6 o'clock.

[0053] Here, the third wiring 21c crossing the third thin portion 12c is referred to as switch No. 0, the second wiring 21b crossing the second thin portion 12b is referred to as switch No. 1, and the first wiring 21a crossing the first thin portion 12a is referred to as switch No. 2. In this case, when there are three switches, the wiring 21 (21a to 21c) is arranged to extend in the order of switch No. 0, switch No. 1, and switch No. 2, rotated clockwise by 60°.

[0054] If more switches are to be arranged, according to this rule, for example, if there are six switches, the wiring 21 is arranged so that it extends in directions rotated by 30 degrees, and if there are 12 switches, the wiring 21 is arranged so that it extends in directions rotated by 15 degrees.

[0055] Other than this, the configuration is similar to that of printed wiring board 1 shown in FIGS. 1 to 3, so the same members are given the same reference numerals and the description thereof will not be repeated unless necessary.

[0056] Next, an example of a wire trimming method for trimming wires 21 on the above-described printed wiring board 1 will be described. Trimming of wires 21 is performed by breaking through thin-walled portion 12 across which desired wire 21 crosses. As shown in Figures 18 and 19, here, an example will be given in which first wire 21a crossing first thin-walled portion 12a is cut.

[0057] As described in the first embodiment, a tool (not shown) with a pointed tip is inserted into the first cut hole 11a and pressure is applied to the first thin-walled portion 12a, thereby forcing the first thin-walled portion 12a to break through. By forcing the first thin-walled portion 12a to break through, the first wiring 21a arranged to cross the first thin-walled portion 12a is cut.

[0058] In the above-described printed wiring board 1, the wiring 21 that crosses one thin portion 12 is considered to be one switch, and the pattern of the wiring 21 differs for each switch. This eliminates the need to identify each switch by silk-screened letters or numbers, etc. As a result, the switch number or bit number, etc. can be visually identified, and the first wiring 21a to be cut can be easily identified.

[0059] In the above-described printed wiring board 1, markings may be printed around the cut holes 11. Also, dots may be printed, for example, at intervals of 10° around the cut holes 11. Such simple printing allows the inclination of the direction in which the wiring 21 extends relative to the end face 3b to be grasped as an absolute value, thereby preventing misreading.

[0060] Embodiment 4 A description will be given of a printed wiring board and a wire trimming method according to embodiment 4. First, an example of a printed wiring board will be described.

[0061] 20 and 21, a through hole 23 is formed in the thin portion 12 located at the bottom of the cut hole 11, penetrating the thin portion 12, and a plating layer 25 serving as a conductive film is formed on the inner wall surface of the through hole 23. That is, a through hole (or inner via) is formed in the thin portion 12. One end and the other end of the wiring 21 that crosses the thin portion 12 are electrically connected by the plating layer 25.

[0062] The through holes 23 include a first through hole 23a, a second through hole 23b, and a third through hole 23c. The plating layer 25 includes a first plating layer 25a, a second plating layer 25b, and a third plating layer 25c. The first plating layer 25a is formed on the inner wall surface of the first through hole 23a. The second plating layer 25b is formed on the inner wall surface of the second through hole 23b. The third plating layer 25c is formed on the inner wall surface of the third through hole 23c.

[0063] Such a printed wiring board 1 is formed as follows. First, a through hole 23 is formed through the printed wiring board 1 in a state where no cut hole 11 has been formed, and a plating layer 25 is formed on the inner wall surface of the through hole 23. Next, a cut hole 11 is formed in the printed wiring board 1. At this time, as shown in FIG. 21 , the plating layer 25 is removed together with the substrate 5, leaving behind a thin portion 12 located at the bottom of the cut hole 11 (see the two-dot chain line).

[0064] Other than this, the configuration is similar to that of printed wiring board 1 shown in FIGS. 1 to 3, so the same members are given the same reference numerals and the description thereof will not be repeated unless necessary.

[0065] Next, an example of a wire trimming method for trimming wires 21 on the above-described printed wiring board 1 will be described. Trimming of wires 21 is performed by breaking through thin-walled portion 12 across which desired wire 21 crosses. As shown in Figs. 22 and 23, here, an example will be given in which first wire 21a crossing first thin-walled portion 12a is cut.

[0066] As described in the first embodiment, a tool (not shown) with a pointed tip is inserted into the first cut hole 11a and pressure is applied to the first thin-walled portion 12a, thereby forcing the first thin-walled portion 12a to break through. By forcing the first thin-walled portion 12a to break through, the first wiring 21a arranged to cross the first thin-walled portion 12a is cut.

[0067] In the above-described printed wiring board 1, the first thin-walled portion 12a has the first plating layer 25a embedded in a ring shape, and the joint surface between the first plating layer 25a and the resin 7 is positioned so as to penetrate the first thin-walled portion 12a (base material 5). Therefore, compared to a solid thin-walled portion 12 in which the base material 5 does not have through-holes 23 and plating layer 25 formed therein, the rigidity of the base material 5 in the first thin-walled portion 12a is weakened. This allows the first thin-walled portion 12a to be broken with a smaller pressing force, making it easier to cut the first wiring 21a.

[0068] The cut holes 11 where the thin-walled portions 12 that do not cut the wiring 21 are located may be filled with a resin adhesive. Also, a plastic pin for indicating a short circuit may be inserted into the cut holes 11. By treating the cut holes 11 in this way, the plating layer 25 exposed in the thin-walled portions 12 can be protected.

[0069] Furthermore, since through holes 23 are formed in printed wiring board 1 in advance, it becomes easy to position a tool when forming cutting holes 11. When forming cutting holes 11 in printed wiring board 1, for example, a drill is used as a tool. At this time, by aligning the tip of the drill with the position of through holes 23, highly accurate processing can be performed.

[0070] Embodiment 5 A printed wiring board and a wire trimming method according to embodiment 5 will be described. First, an example of a printed wiring board will be described. Here, a printed wiring board in which thin-walled portions having different thicknesses are formed with respect to thin-walled portions across which wires cross will be described.

[0071] As shown in Figures 24 and 25, in printed wiring board 1, first thin-walled portion 12a located at the bottom of first cut hole 11a has a thickness T1 as a second thickness. Second thin-walled portion 12b located at the bottom of second cut hole 11b has a thickness T2. Third thin-walled portion 12c located at the bottom of third cut hole 11c has a thickness T3 as a third thickness. Thickness T1 is thinner than both thicknesses T2 and T3. Thickness T3 is thinner than thickness T2.

[0072] Other than this, the configuration is similar to that of printed wiring board 1 shown in FIGS. 1 to 3, so the same members are given the same reference numerals and the description thereof will not be repeated unless necessary.

[0073] In the above-described printed wiring board 1, first wiring 21a is arranged to cross first thin portion 12a, which has the thinnest thickness T1. Second wiring 21b is arranged to cross second thin portion 12b, which has the thickest thickness T2. Third wiring 21c is arranged to cross third thin portion 12c, which has a thickness T3 that is thicker than thickness T1 but thinner than thickness T2.

[0074] The thermal conductivity of thin-walled portion 12 approaches that of air as the thickness of thin-walled portion 12 decreases, resulting in a decrease in heat dissipation. Therefore, wiring 21 arranged to cross thin-walled portion 12 is more likely to generate heat when current is applied.

[0075] By utilizing this property, the wiring 21 can be made to function as a fuse. When a current flows through the wiring 21, Joule heat is generated in the wiring 21. The wiring 21 can be melted down by the Joule heat.

[0076] Depending on the thickness of the thin-walled portion 12 (substrate 5), the thinner the thin-walled portion 12, the more easily the wiring 21 generates heat. On the other hand, the thicker the thin-walled portion 12, the more easily the heat of the wiring 21 is dissipated. For this reason, by specifying the thickness of the thin-walled portion 12 so that the temperature at which the wiring 21 melts for any current value, the wiring 21 becomes a fuse (wiring) that cuts off the circuit at the set current value.

[0077] To disconnect the wiring 21, it is sufficient to pass a current required to fuse the wiring 21. By providing a circuit operation that passes a current through the wiring, the wiring 21 can be automatically disconnected (fused) without the intervention of an operator. This allows, for example, when performing an electrical check using a function tester or the like during pre-shipment inspection, to fuse the specified wiring by passing a current through the specified wiring at the same time, thereby switching the circuit provided on the printed wiring board 1.

[0078] 24 and 25 is formed with a power supply circuit corresponding to three different supply voltages (V1=AC 220V, V2=AC 127V, V3=AC 100V) as shown in Fig. 26. In the power supply circuit, first wiring 21a, second wiring 21b, and third wiring 21c serving as fuses 41 are formed for three taps of coil 33 on the primary side of transformer 31 to which voltage is input, so that the circuit is cut off when the output of coil 35 on the secondary side of transformer 31 exceeds the rated power of transformer 31, for example, 200 W.

[0079] The first wiring 21a is formed as a first fuse 41a in the circuit of voltage V1 (AC 220V, current 0.9A) and crosses the first thin-walled portion 12a. The second wiring 21b is formed as a third fuse 41c in the circuit of voltage V3 (AC 100V, current 2.0A) and crosses the second thin-walled portion 12b. The third wiring 21c is formed as a second fuse 41b in the circuit of voltage V2 (AC 127V, current 1.5A) and crosses the third thin-walled portion 12c.

[0080] Next, the fuse 41 corresponding to one of the three power supply voltages that is not to be used as a power supply voltage at the shipping destination is blown. As shown in Figures 27 and 28, for example, if the voltage V1 (AC 220V) is not to be used, the first fuse 41a (first wiring 21a) is blown by passing a current through the first wiring 21a that melts the first wiring 21a at the time of shipping.

[0081] On the other hand, for the voltage V2 or voltage V3 used, the second wiring 21b and the third wiring 21c function as a fuse 41 (third fuse 41c, second fuse 41b) that melts when the rated power (200 W) of the transformer 31 is exceeded.

[0082] In the printed wiring board 1 described above, when a shipping destination has a different power supply voltage, it is possible to leave only the fuses that correspond to the power supply voltage of the shipping destination without replacing the fuses.

[0083] The printed wiring boards described in the respective embodiments can be combined in various ways as needed. For example, the printed wiring board 1 according to the first to fourth embodiments may be provided with the fuse described in the fifth embodiment.

[0084] The embodiments disclosed herein are examples and are not intended to be limiting. The scope of the present disclosure is defined by the claims, not the scope described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0085] The present disclosure includes the following aspects.

[0086] [Appendix 1] a substrate including glass fibers, the substrate having opposing first and second major surfaces and a first thickness; one or more wirings formed on the first main surface of the substrate and to be trimmed; Equipped with the substrate includes one or more thin-walled portions formed on the first main surface side, corresponding to one or more of the wirings, thinner than the first thickness, and not containing the glass fiber; A printed wiring board, wherein one or more of the wirings are formed to cross a corresponding one of the thinned portions.

[0087] [Appendix 2] 2. The printed wiring board according to claim 1, wherein the thin portion is formed at a position away from a first end surface of the substrate.

[0088] [Appendix 3] 2. The printed wiring board according to claim 1, wherein the thin portion is formed from a first end surface of the substrate toward an inner region of the substrate.

[0089] [Appendix 4] The thin-walled portion is a first thin-walled portion; The second thin-walled section and Including, The wiring is a first wiring extending across the first thin portion; a second wiring extending across the second thin portion; 4. The printed wiring board according to any one of claims 1 to 3, comprising:

[0090] [Appendix 5] the substrate has a second end surface extending in one direction; the first wiring extends at a first angle with respect to the second end surface; 5. The printed wiring board according to claim 4, wherein the second wiring extends at a second angle relative to the second end face, the second angle being different from the first angle.

[0091] [Appendix 6] The printed wiring board according to any one of claims 1 to 3, wherein the thin-walled portion has a tubular conductive film formed along the inner wall surface of a through hole penetrating the thin-walled portion, the conductive film being electrically connected to the wiring.

[0092] [Appendix 7] The thin-walled portion is a third thin-walled portion having a second thickness that is thinner than the first thickness; a fourth thin-walled portion having a third thickness that is thinner than the first thickness and thicker than the second thickness; Including, The wiring is a third wiring extending across the third thin portion; a fourth wiring extending across the fourth thin portion; and Including, the third wiring includes a first fuse; 4. The printed wiring board according to claim 1, wherein the fourth wiring includes a second fuse.

[0093] [Appendix 8] The printed wiring board according to any one of appendixes 1 to 7, wherein the thin portion is located at the bottom of an opening formed from the second main surface toward the first main surface, with a thickness corresponding to the thin portion remaining from the first main surface. [Industrial Applicability]

[0094] The present disclosure is effectively applied to printed wiring boards having a substrate containing glass fibers. [Explanation of symbols]

[0095] 1 printed wiring board, 1a first main surface, 1b second main surface, 3a, 3b end surface, 5 substrate, 5a first substrate, 5b second substrate, 5c third substrate, 7 resin, 9 glass fiber, 11 cut hole, 11a first cut hole, 11b second cut hole, 11c third cut hole, 12 thin portion, 12a first thin portion, 12b second thin portion, 12c third thin portion, 13 cut portion, 15 cut portion, 17 melted portion, 19 melted portion, 21 wiring, 21a first wiring, 21b second wiring, 21c third wiring, 23 through hole, 23a first through hole, 23b second through hole, 23c third through hole, 25 plating layer, 25a first plating layer, 25b second plating layer, 25c third plating layer, 31 transformer, 33 Primary coil, 35 Secondary coil, 41 Fuse, 41a First fuse, 41b Second fuse, 41c Third fuse, 51 Plastic pin, 53 Insulating pin, T, T1, T2, T3 Thickness.

Claims

1. a substrate including glass fibers, the substrate having opposing first and second major surfaces and a first thickness; one or more wirings formed on the first main surface of the substrate and to be trimmed; Equipped with the substrate includes one or more thin-walled portions formed on the first main surface side, corresponding to one or more of the wirings, thinner than the first thickness, and not containing the glass fiber; A printed wiring board, wherein one or more of the wirings are formed to cross a corresponding one of the thinned portions.

2. The printed wiring board according to claim 1 , wherein the thin portion is formed at a position away from a first end surface of the substrate.

3. The printed wiring board according to claim 1 , wherein the thin portion is formed from the first end surface of the substrate toward an inner region of the substrate.

4. The thin-walled portion is A first thin-walled portion; The second thin-walled portion and Including, The wiring is a first wiring extending across the first thin portion; a second wiring extending across the second thin portion; The printed wiring board according to any one of claims 1 to 3, comprising:

5. the substrate has a second end surface extending in one direction; the first wiring extends at a first angle with respect to the second end surface; The printed wiring board according to claim 4 , wherein the second wiring extends at a second angle relative to the second end face, the second angle being different from the first angle.

6. The printed wiring board according to any one of claims 1 to 3, wherein a tubular conductive film electrically connected to the wiring is formed in the thin-walled portion along an inner wall surface of a through hole penetrating the thin-walled portion.

7. The thin-walled portion is a third thin-walled portion having a second thickness that is thinner than the first thickness; a fourth thin-walled portion having a third thickness that is thinner than the first thickness and thicker than the second thickness; and Including, The wiring is a third wiring extending across the third thin portion; a fourth wiring extending across the fourth thin portion; Including, the third wiring includes a first fuse; 4. The printed wiring board according to claim 1, wherein the fourth wiring includes a second fuse.

8. The printed wiring board according to any one of claims 1 to 3, wherein the thin-walled portion is located at the bottom of an opening formed from the second main surface toward the first main surface, with a thickness corresponding to the thin-walled portion remaining from the first main surface.

9. 1. A wire trimming method for trimming one or more wires formed on a first main surface of a substrate including glass fiber, the substrate having a first main surface and a second main surface opposite to each other and a first thickness, the method comprising: the substrate has one or more thin-walled portions that are thinner than the first thickness and do not contain the glass fiber, the thin-walled portions corresponding to one or more of the wirings, One or more of the wirings are formed to cross the corresponding thin-walled portion, A wiring trimming method for trimming one or more of the wirings that should be trimmed.

10. 10. The wire trimming method according to claim 9, wherein the process of trimming the wire includes a process of removing the thinned portion where the wire is located in a manner of cutting the wire.

11. a cylindrical conductive film electrically connected to the wiring is formed on the thin-walled portion along an inner wall surface of a through hole that penetrates the thin-walled portion; 10. The wire trimming method according to claim 9, wherein the process of trimming the wire includes a process of removing the cylindrical conductive film in a manner that cuts the wire.

12. As the thin-walled portion, two or more thin-walled portions having thicknesses different from each other are formed, 10. The wiring trimming method according to claim 9, wherein the process of trimming the wiring includes a process of fusing the wiring by Joule heat generated by passing a current through the wiring that melts the wiring in accordance with the thickness of the thin-walled portion.

13. 1. A wire trimming method for trimming one or more wires formed on a first main surface of a substrate including glass fiber and having a first main surface and a second main surface opposite to each other, the method comprising: A wiring trimming method comprising a process of cutting, by router processing, the wiring to be trimmed together with the substrate from an end face of the substrate.

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