Circuit board manufacturing method

Abstract

To provide a circuit substrate and a manufacturing method for the same, in particular, that can eliminate the need to check the appearance of patterns for resistance value adjustments, make work efficiency improved, and stabilize the resistance characteristics.SOLUTION: The circuit substrate includes a resistive element (1a) having a pattern for adjusting resistance values and a trimming start mark (20) indicating a position of a trimming start point with respect to the pattern for adjusting resistance values. The trimming start mark has a first mark (23) and a second mark (24) that is spaced with respect to the first mark and opposes the first mark on a side away from the pattern for adjusting resistance values.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a circuit board having a resistor element having a resistance value adjustment pattern and a trimming start mark on an insulating substrate. [Background technology]

[0002] Circuit boards used in thin-film resistors are provided with thin-film resistors with a predetermined pattern formed by vapor deposition or photolithography technology. The thin-film resistors are formed in a repeatedly folded pattern (also called a meander pattern) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 64-57601 Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention described in Patent Document 1, a film resistor having a resistance value adjustment pattern and a trimming position alignment pattern are formed on an insulating substrate. Then, trimming is started from a laser irradiation start position approximately 20 μm to 100 μm away from the trimming position alignment pattern.

[0005] However, in the invention described in Patent Document 1, when a positional deviation occurs in the trimming start point, the only way to determine whether trimming has been performed correctly is to visually check the trimmed resistance value adjustment pattern. In particular, when the resistance value adjustment pattern is a meander pattern that is repeatedly folded back, and trimming is performed across the meander pattern, if a positional deviation occurs in the trimming start point, there is a high risk of leaving uncut portions in the resistance value adjustment pattern. There is a problem in that the resistance load increases in the areas where uncut portions occur, resulting in unstable resistance characteristics.

[0006] Therefore, in the past, it was necessary to check the appearance of each trimmed resistance-adjustment pattern one by one to see if any part of the resistance-adjustment pattern remained uncut, which was extremely cumbersome.

[0007] Therefore, the present invention has been made in consideration of the above problems, and particularly aims to provide a circuit board and a manufacturing method thereof that can eliminate the need to check the appearance of resistance value adjustment patterns, improve work efficiency, and reduce the risk of leaving any uncut areas due to trimming. [Means for solving the problem]

[0012] The method for manufacturing a circuit board according to the present invention includes the steps of: A method for manufacturing a circuit board in which a resistor is formed on an insulating substrate, the resistor having a resistance value adjustment pattern, and a trimming start mark formed near the resistance value adjustment pattern, the trimming start mark consisting of a first mark on a side closer to the resistance value adjustment pattern and a second mark formed on a side farther from the resistance value adjustment pattern, the method comprising: a trimming step of performing trimming from a predetermined trimming start point and cutting a part of the trimming start mark and the resistance value adjustment pattern, the trimming start point being set between the first mark and the second mark, and the trimming start mark after trimming is in a state in which the central part of the first mark is removed, leaving only parts on both sides, and the second mark remaining undivided. , characterized by: In the present invention, it is preferable that the trimming start mark includes a connecting portion that connects the first mark and the second mark. In the present invention, it is preferable that the width of the first mark in the direction toward the second mark is wider than the width of the second mark. [Effects of the Invention]

[0016] In the present invention, by visually checking the trimming start mark, it is possible to determine whether the positional deviation of the trimming start point is within the tolerance range, thereby improving work efficiency. Furthermore, it is possible to reduce the risk of leaving uncut parts after trimming, and to stabilize the resistance characteristics. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a plan view of a thin-film resistor having a resistance-adjustment pattern according to an embodiment of the present invention; [Figure 2] 10(a) and 10(b) are enlarged plan views of a resistance adjustment pattern and a trimming start mark for explaining problems with the trimming start mark in the comparative example. [Figure 3] FIG. 3 is an enlarged plan view of a trimming start mark in the first embodiment of the present invention. [Figure 4] 4 is an enlarged plan view showing a trimming start mark and a resistance value adjustment pattern shown in FIG. 3. FIG. [Figure 5]FIG. 10A is an enlarged plan view showing the trimming start mark after trimming when the position of the trimming start point is within the tolerance range specified in the trimming start mark, and FIGS. 10B to 10D are enlarged plan views showing the trimming start mark after trimming when the position of the trimming start point is outside the tolerance range specified in the trimming start mark. [Figure 6] 4(a) and 4(b) are enlarged plan views showing a trimming start mark having a different shape from the trimming start mark of the first embodiment shown in FIG. 3. [Figure 7] 1 is a partial cross-sectional view of a thin film resistor provided with a circuit board according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail below. Note that the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0019] The circuit board of this embodiment is applied to chip resistors, thin film resistor networks, etc. For example, a thin film resistor 10 equipped with the circuit board 9 of this embodiment has a cross-sectional view shown in FIG.

[0020] As shown in Fig. 7, a thin-film resistor 1 consisting of a pattern in which resistive wiring is repeatedly folded is formed on the surface of an insulating substrate 2. Surface electrodes 3a and 3b are formed on the surfaces of both ends of the thin-film resistor 1, respectively, and the thin-film resistor 1 and the surface electrodes 3a and 3b are electrically connected. In addition, back electrodes 3c and 3d are formed on the back surface of the insulating substrate 2. The insulating substrate 2, the thin-film resistor 1, and the surface electrodes 3a and 3b together constitute a circuit board.

[0021] 7, the surface of the thin-film resistor 1 exposed from the surface electrodes 3a, 3b is covered with a protective film 14. Also, as shown in Fig. 7, external electrode plating 19a, 19b is applied to the ends of the protective film 14 so as to cover the surface electrodes 3a, 3b and the back electrodes 3c, 3d.

[0022] Although there is no limitation on the material, the insulating substrate 2 is made of, for example, ceramics such as sintered alumina having electrical insulation properties. The thin-film resistor 1 is made of, for example, nickel-chromium (NiCr). The front electrodes 3a, 3b and rear electrodes 3c, 3d are formed of a conductive material having better electrical conductivity than the thin-film resistor 1. The protective film 14 is formed of, for example, an epoxy-based insulating resin. The external electrode platings 19a, 19b are formed by plating with, for example, nickel.

[0023] <Outline of Thin Film Resistor 1> FIG. 1 is a plan view of a thin-film resistor 1 having a resistance-adjustment pattern according to this embodiment of the present invention. The X1-X2 direction and the Y1-Y2 direction shown in FIG.

[0024] The thin-film resistor 1 shown in Figure 1 is formed on the surface of the insulating substrate 2 shown in Figure 7, and together with the insulating substrate 2 constitutes a circuit board 9, but in the drawing, the insulating substrate 2 is omitted and only the thin-film resistor 1 is shown.

[0025] As shown in Fig. 1, the thin-film resistor 1 has a meander-shaped resistor pattern 1a in which resistor wiring extends in the Y1-Y2 direction and is alternately folded back to face each other at a predetermined interval in the X1-X2 direction. Wide portions 1e and 1f, which are wider than the wiring width, are formed on both ends of the resistor pattern 1a in the X1-X2 direction. Surface electrodes 3a and 3b are formed on the surfaces of the wide portions 1e and 1f, respectively.

[0026] As shown in Fig. 1, a resistance-adjustment pattern 6 is formed integrally with the resistor pattern 1a between adjacent folded ends 5 in the X1-X2 direction on the Y2 side of the resistor pattern 1a. The resistance-adjustment pattern 6 extends in the Y2 direction from the folded end 5 on the Y2 side, and multiple resistance-adjustment patterns 6 are formed side by side at intervals in the X1-X2 direction. The multiple resistance-adjustment patterns 6 are connected by a connecting pattern 7 on the Y2 side. With the pattern configuration shown in Fig. 1, the resistance of the resistor pattern 1a can be adjusted by trimming the resistance-adjustment pattern 6.

[0027] As shown in FIG. 1, a trimming start mark 20 is formed near the resistance-adjustment pattern 6.

[0028] In this embodiment, the trimming start point is aligned with the position of trimming start mark 20, and trimming is started toward resistance value adjustment pattern 6 as shown by the arrow in Fig. 1, and trimming is finished when a predetermined resistance value is reached. In contrast, the trimming position alignment pattern shown in Patent Document 1 is not a mark for aligning the trimming start point to that position, but rather trimming is started from a location away from the trimming position alignment pattern, and is not a trimming start mark having the same purpose and function as this embodiment. A comparative example of the trimming start mark and the shape of this embodiment will be described below.

[0029] <Resistance Adjustment Patterns in Comparative Examples and Their Problems> 2(a) and 2(b), a substantially square trimming start mark 21 is provided near the X2 side of the resistance-value-adjustment pattern 6. The trimming start mark 21 shown in FIGS. 2(a) and 2(b) is a comparative example.

[0030] Figure 2(a) shows a case where there is no misalignment in the trimming start point A and trimming has been performed normally. The dotted line portion in Figures 2(a) and 2(b) is the trimming area 22. Therefore, the resistance value adjustment pattern 6 within the trimming area 22 is removed. By removing the resistance value adjustment pattern 6, the length of the resistor pattern 1a is shortened, and the resistance value of the resistor pattern 1a can be reduced.

[0031] Here, "trimming start point A" refers to the tip portion located at the end closest to the side where trimming starts (i.e., the position closest to X2 in FIG. 2(a)). As shown in the trimming area 22 in FIG. 2(a), trimming is performed from the trimming start mark 21 in the X1 direction, and a total of two resistance-adjustment patterns 6 are cut.

[0032] In contrast, in Figure 2(b), a positional deviation occurs in trimming start point A. In Figure 2(b), trimming start point A is shifted toward the X1 side from the correct position. As a result, trimming region 22 also shifts toward the X1 side, and a portion of the third resistance-value-adjustment pattern 6 remains uncut (see region B shown in Figure 2(b)).

[0033] In particular, to achieve a high resistance value, the pitch of each resistor pattern 1a is narrowed in order to extend the length of the resistor pattern 1a, which in turn narrows the pitch of each resistance value adjustment pattern 6. For this reason, if there is a positional deviation in the trimming start point A, as shown in Figure 2(b), it is easy for uncut portions to remain in the resistance value adjustment pattern 6. The uncut portions increase the resistance load, causing the problem of unstable resistance characteristics.

[0034] Furthermore, as described above, when a positional deviation occurs in the trimming start point A, whether or not there is an uncut portion in the resistance-value-adjustment pattern 6 can only be determined by checking the appearance of each trimmed resistance-value-adjustment pattern 6, which makes the checking process extremely cumbersome. That is, the trimming start mark 21 of the comparative example shown in Fig. 2 only functions as a mark for registering the trimming start coordinate position, and checking for an uncut portion requires direct checking of the appearance of the resistance-value-adjustment pattern 6.

[0035] As described above, in the comparative example, each resistance value adjustment pattern must be checked one by one to determine whether or not there are any remaining cuts. In other words, since the checking work is performed at multiple locations, the risk of remaining cuts increases, the resistance characteristics cannot be properly stabilized, and the yield decreases.

[0036] <Outline of Resistance Adjustment Pattern in the Present Embodiment> Fig. 3 is an enlarged plan view of a trimming start mark in the first embodiment of the present invention, and Fig. 4 is an enlarged plan view showing the trimming start mark and resistance value adjustment pattern shown in Fig. 3.

[0037] 4, the trimming start mark 20 is disposed, for example, near the left side (X2 side) of the resistance value-adjusting pattern 6. Although not limited thereto, it is preferable that the trimming start mark 20 be made of the same material as the thin-film resistor 1.

[0038] As shown in Figures 3 and 4, the trimming start mark 20 is composed of a first mark 23 arranged on the side closer to the resistance value adjustment pattern 6 (X1 side), and a second mark 24 arranged at a distance from the first mark 23 on the side farther from the resistance value adjustment pattern 6 (X2 side).

[0039] The first mark 23 and the second mark 24 face each other with a gap in the X1-X2 direction, which is the trimming direction from the trimming start mark 20 toward the resistance value-adjusting pattern 6.

[0040] As shown in Fig. 3, the first mark 23 is a substantially rectangular pattern having a first width T1 in the X1-X2 direction and a first length L1 in the Y1-Y2 direction perpendicular to the X1-X2 direction. The second mark 24 is a substantially rectangular pattern having a second width T2 in the X1-X2 direction and a second length L2 in the Y1-Y2 direction. As shown in Fig. 3, the first width T1 is wider than the second width T2. Although the first length L1 and the second length L2 are substantially the same in Fig. 3, they may be slightly different.

[0041] 3, a connecting portion 25 is formed to connect the first mark 23 and the second mark 24. The connecting portion 25 is preferably formed at the center of the lengths L1 and L2 of the first mark 23 and the second mark 24. The connecting portion 25 is preferably formed parallel to the X1-X2 direction.

[0042] 4, trimming is performed on the resistance-value-adjustment patterns 6 in the X1 direction from the trimming start mark 20. Reference numeral 22 in FIG. 4 denotes a trimming region, and three resistance-value-adjustment patterns 6 are cut by trimming.

[0043] In this embodiment, the first mark 23 and the second mark 24 are arranged at an interval in the X1-X2 direction, which is the trimming direction, so that the allowable range C of misalignment of the trimming start point A in the trimming direction can be narrowed down to, for example, a limited area between the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24. On the other hand, in the trimming start mark 21 of the comparative example shown in FIG. 2, the allowable range of misalignment of the trimming start point A in the trimming direction cannot be narrowed down to a limited range within the trimming start mark 21.

[0044] In this embodiment, if the position of the trimming start point A is within the allowable range C of the trimming start mark 20, there will be no uncut portions as shown in Figure 2(b). On the other hand, if the position of the trimming start point A is outside the allowable range C of the trimming start mark 20, there will be more likely to be uncut portions as shown in Figure 2(b).

[0045] When the trimming start mark 21 of the comparative example shown in FIG. 2 is used, it is not possible to determine whether or not there are any remaining uncut portions without checking the appearance of each of the resistance value adjustment patterns 6. However, in this embodiment, by checking the appearance of the trimming start mark 20, it is possible to determine whether or not the positional deviation is within an acceptable range that will not result in any remaining uncut portions.

[0046] <Regarding the appearance check of the trimming start mark 20 in this embodiment> Figure 5(a) is an enlarged plan view of the trimming start mark when the position of the trimming start point A is within the allowable range of the trimming start mark, and (b) to (d) are enlarged plan views of the trimming start mark when the position of the trimming start point A is outside the allowable range of the trimming start mark.

[0047] Note that Figures 5(a) to 5(d) all show the state after trimming, so the trimmed area relative to the trimming start mark 20 has been removed, but to make it easier to see, the trimming area 22 is shown with a dotted line, and the part of the trimming start mark 20 that will be removed is indicated with a two-dot chain line.

[0048] As shown in FIG. 5(a), the position of the trimming start point A is within the tolerance range C. That is, the trimming start point A is located between the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24. At this time, by using the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24, which are located at both ends of the tolerance range C, as appearance check lines, it is possible to determine that the position of the trimming start point A is within the tolerance range C. That is, as shown in FIG. 5(a), after trimming, a portion of the inner side 23a of the first mark 23 (the double-chain line 23e shown in FIG. 5(a)) has been removed, and only portions of the inner side 23a of the first mark 23 remain on both sides in the Y1-Y2 direction. On the other hand, the outer side 24b of the second mark 24 remains untrimmed. Therefore, by checking the appearance after trimming of the inner edge 23a of the first mark 23 and the outer edge 23b of the second mark 24, which are the two end lines of the tolerance range C, it can be recognized that the position of the trimming start point A is within the tolerance range C.

[0049] On the other hand, in FIG. 5(b), the position of the trimming start point A deviates from the allowable range C toward the X2 side. In this case, not only a part of the inner side 23a of the first mark 23 (double-chain line 23e shown in FIG. 5(b)), but also a part of the outer side 24b of the second mark 24 (double-chain line 24e shown in FIG. 5(b)) has been trimmed, and only a portion of each of the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 remains. If the appearance can be confirmed as described above, it can be determined that the position of the trimming start point A deviates from the allowable range C toward the X2 side.

[0050] 5(c), the position of the trimming start point A is off to the X1 side of the allowable range C. In this case, both the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 are left untrimmed. If the appearance can be confirmed as above, it can be determined that the position of the trimming start point A is off to the X1 side of the allowable range C.

[0051] As described above, in this embodiment, the positional deviation of the trimming start point A in the trimming direction (X1-X2 direction) can be determined by visually checking the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24, which are located at both ends of the tolerance range C of the trimming start mark 20, and there is no need to check the appearance of the resistance value adjustment patterns one by one as explained in the comparative example of Fig. 2. Therefore, in this embodiment, the visual check work after trimming can be significantly shortened, and the ease of the check work can reduce the risk of leaving uncut portions due to trimming, and the resistance characteristics can be appropriately stabilized.

[0052] 5(a) to 5(c) have also described a method for checking whether the position of the trimming start point A is within the tolerance range C in the trimming direction (X1-X2). In addition, in this embodiment, it is also possible to check for positional deviation of the trimming start point A in a direction perpendicular to the trimming direction. For example, in FIG. 5(d), the trimming start point A is within the tolerance range C, but is shifted upward compared to FIG. 5(a). At this time, the appearance of the upper side 23c and lower side 23d of the first mark 23 are checked. The "upper side 23c" and "lower side 23d" refer to the two opposite sides connecting the inner side 23a and outer side 23b of the first mark 23.

[0053] That is, as shown in FIG. 5(a), by confirming that the top side 23c and bottom side 23d of the first mark 23 are left untrimmed, it can be confirmed that the trimming start point A is not misaligned not only in the trimming direction (X1-X2 direction) but also in the direction perpendicular thereto (Y1-Y2 direction). On the other hand, as shown in FIG. 5(d), if it is confirmed that the trimming start point A is misaligned upward (Y1 direction) and the top side 23c of the first mark 23 has been trimmed, it can be determined that the trimming start point A is misaligned upward beyond the allowable range. Similarly, if it is confirmed that the trimming start point A is misaligned downward (Y2 direction) and the bottom side 23d of the first mark 23 has been trimmed, it can be determined that the trimming start point A is misaligned downward beyond the allowable range. Depending on the relationship in magnitude between the length of the trimming area 22 in the Y1-Y2 direction and the first length L1 of the first mark 23 in the Y1-Y2 direction, when there is no misalignment in the Y1-Y2 direction, at least a portion of the upper side 23c and the lower side 23d of the first mark 23 will be trimmed, unlike in Figure 5(a).Therefore, by visually checking the upper side 23c and the lower side 23d of the first mark 23 according to the above relationship in magnitude, it can be determined whether or not there is a misalignment in the Y1-Y2 direction of the trimming starting point A.

[0054] As described above, in this embodiment, by checking the appearance of the trimming start mark 20, it is possible to determine whether the positional deviation of the trimming start point A is within the tolerance range. Specifically, for example, by checking the appearance of the inner side 23a of the first mark 23 on the side closer to the resistance-adjustment pattern and the outer side 24b of the second mark 24 on the side farther from the resistance-adjustment pattern, it is possible to determine whether the position of the trimming start point A is within the tolerance range C in the trimming direction. In addition, for example, by checking the appearance of the upper side 23c and lower side 23d of the first mark 23, it is possible to determine whether the position of the trimming start point A is within the tolerance range in the direction perpendicular to the trimming direction.

[0055] In this manner, in this embodiment, it is possible to determine whether the trimming start point A is within the allowable range of positional deviation simply by visually checking the trimming start mark 20, and there is no need to visually check the resistance value adjustment pattern 6.

[0056] 3, the width T1 of the first mark 23 is wider than the width T2 of the second mark 24. Therefore, the lengths of the upper and lower sides 23c and 23d of the first mark 23 (equal to the width T1) are greater than the lengths of the upper and lower sides 24c and 24d of the second mark 24 (equal to the width T2). Therefore, the positional deviation of the trimming start point A in the Y1-Y2 direction can be accurately determined by visually checking the upper and lower sides 23c and 23d of the first mark 23. That is, because the tip of the trimming region 22 is approximately arc-shaped, if the upper and lower sides 23c and 23d of the first mark 23 are short, even if the trimming start point A is misaligned in the Y1-Y2 direction, the tip of the trimming region 22 and the upper and lower sides 23c and 23d of the first mark 23 may not properly overlap, and the positional deviation in the Y1-Y2 direction may not be accurately determined. Therefore, by extending the upper side 23c and lower side 23d of the first mark 23, if the trimming start point A is displaced in the Y1-Y2 direction, the overlapping range between the tip of the trimming area 22 and the upper side 23c or lower side 23d of the first mark 23 is expanded, and the displacement in the Y1-Y2 direction can be determined with high accuracy.

[0057] <Outline of Resistance Adjustment Pattern in Another Embodiment> 6(a) and 6(b) are enlarged plan views showing trimming start marks having a different shape from the trimming start marks of the first embodiment shown in FIG.

[0058] 6(a), the trimming start mark 26 is composed of a first mark 23 arranged on the side closer to the resistance-adjustment pattern 6 (X1 side) and a second mark 24 facing the first mark 23 at a distance. Unlike FIG. 3, no connecting portion 25 is provided. Also in FIG. 6(a), the tolerance C for misalignment of the trimming start point A in the trimming direction (X1-X2 direction) can be defined, for example, between the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24. The inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 can be used as appearance check lines. Furthermore, with regard to misalignment of the trimming start point A in the direction perpendicular to the trimming direction (Y1-Y2 direction), the upper side 23c and the lower side 23d of the first mark 23 can be used as appearance check lines.

[0059] 6(a), unlike FIG. 3, there is no connecting portion 25 connecting the first mark 23 and the second mark 24, but it is preferable to provide the connecting portion 25. That is, as shown in FIG. 3(a), by overlapping the trimming start point A with the position of the connecting portion 25, it is possible to more accurately determine whether the trimming start point A is within the tolerance range C by visually checking the connecting portion 25. In addition, it is easy to obtain the accurate coordinates of the trimming start point A. It is preferable that the connecting portion 25 is formed so as to connect the centers of the first mark 23 and the second mark 24 in the Y1-Y2 direction.

[0060] Moreover, the trimming start mark 27 shown in FIG. 6(b) is configured to include a first mark 23 arranged on the side closer to the resistance value adjustment pattern 6 (X1 side), a second mark 24 facing the first mark 23 with a gap therebetween, a central connecting portion 28 connecting the centers of the first mark 23 and the second mark 24 in the Y1-Y2 direction, an upper side connecting portion 29 connecting the Y1 side end portions of the first mark 23 and the second mark 24 in the Y1-Y2 direction, and a lower side connecting portion 30 connecting the Y2 side end portions of the first mark 23 and the second mark 24 in the Y1-Y2 direction.

[0061] 6(b), the trimming start mark 27 can also define the tolerance C for misalignment of the trimming start point A in the trimming direction (X1-X2 direction) between the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24, and the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 can be used as an appearance confirmation line. Also, in FIG. 6(b), the first mark 23 and the second mark 24 are connected not only by the central connecting portion 28 but also by the upper side connecting portion 29 and the lower side connecting portion 30, and the upper side 29a of the upper side connecting portion 29 and the lower side 30a of the lower side connecting portion 30 can be used as an appearance confirmation line for determining whether the trimming start point A is misaligned in the direction perpendicular to the trimming direction.

[0062] As shown in Figure 6(b), the upper side 29a of the upper side connecting portion 29 and the lower side 30a of the lower side connecting portion 30 are longer than the upper side 23c and lower side 23d of the first mark 23 shown in Figures 3 and 6(a), so it is possible to more accurately determine the positional deviation in a direction perpendicular to the trimming direction of the trimming starting point A.

[0063] In the above description, the tolerance C for misalignment of the trimming start point A in the trimming direction is set between the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24, and the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 are set as the appearance check lines. However, the inner side 23a of the first mark 23 and the inner side 24a of the second mark 24 can also be set as the appearance check lines. As a result, the tolerance C for misalignment of the trimming start point A in the trimming direction becomes the distance between the first mark 23 and the second mark 24. In other words, one appearance check line of the tolerance C is defined by the inner side 23a of the first mark 23, but the other appearance check line can be defined on either the inner side 23a or the outer side 23b depending on the distance between the first mark 23 and the second mark 24.

[0064] <Method of Manufacturing Circuit Board in the Present Embodiment> A method for manufacturing circuit board 9 in this embodiment will be described.

[0065] First, a resistive film is formed on the entire surface of insulating substrate 2 by an existing method such as sputtering. Then, the resistive film is patterned into the shape of thin-film resistor 1 having a resistance value adjustment pattern as shown in FIG. 1. At this time, it is preferable to pattern the resistive film into the shape of trimming start mark 20 simultaneously with the patterning of thin-film resistor 1. This allows thin-film resistor 1 having a resistance value adjustment pattern and trimming start mark 20 to be formed simultaneously on the surface of insulating substrate 2. Furthermore, thin-film resistor 1 having a resistance value adjustment pattern and trimming start mark 20 can be formed from the same material.

[0066] In this embodiment, the trimming start mark 20 is formed of at least a first mark 23 disposed closer to the resistance-adjustment pattern 6 and a second mark 24 facing the first mark 23 with a gap therebetween. As shown in FIG. 3, the first mark 23 and the second mark 24 are preferably connected by a connecting portion 25. Also, as shown in FIG. 3, it is preferable that the width T1 of the first mark 23 is wider than the width T2 of the second mark 24.

[0067] Next, in this embodiment, trimming is performed from the position of the trimming start mark 20 toward the resistance-adjustment pattern 6, as shown in FIG.

[0068] In this embodiment, after trimming of the resistance value-adjusting pattern 6 is completed, the appearance of the trimming start mark 20 is checked to determine whether the position of the trimming start point A is within the tolerance range. That is, as shown in Fig. 5(a), for example, the appearance of the inner side 23a of the first mark 23 and the outer side 24b of the second mark 24 is checked, and in a state in which the inner side 23a of the first mark 23 has been partially removed by trimming and the outer side 24b of the second mark 24 remains untrimmed, it can be determined that the position of the trimming start point A is within the tolerance range C. On the other hand, when a portion of both the inner side 23 a of the first mark 23 and the outer side 24 b of the second mark 24 has been trimmed away, as shown in FIG. 5( b), or when both the inner side 23 a of the first mark 23 and the outer side 24 b of the second mark 24 remain untrimmed, as shown in FIG. 5( c), the position of the trimming start point A can be determined to be outside the tolerance range C. Also, as an example, when it is confirmed that the appearance of the top side 23 c and the bottom side 23 d of the first mark 23 remains untrimmed, as shown in FIG. 5( a), it can be determined that the trimming start point A is not misaligned in the trimming direction or in a direction perpendicular to the trimming direction and is within the tolerance range. Furthermore, when it is confirmed that the appearance of the top side 23 c of the first mark 23 has been trimmed away, as shown in FIG. 5( d), it can be determined that the trimming start point A is misaligned in a direction perpendicular to the trimming direction.

[0069] 5(b) to 5(d), it is found that the trimming start point A is misaligned, and there is a risk that a portion of the resistance value adjustment pattern will remain uncut. Therefore, after correcting the coordinate position of the trimming start point A, trimming is performed again on another row of resistance value adjustment patterns. When the appearance of the trimming start mark 20 shown in FIG. 5(a) is obtained, it is found that the misalignment of the trimming start point A is within the allowable range, that is, it can be determined that no portion of the resistance value adjustment pattern will remain uncut.

[0070] As described above, in this embodiment, it is possible to easily determine whether the positional deviation of the trimming start point A is within the allowable range or not simply by visually checking the trimming start mark 20. This makes it possible to reduce the risk of leaving any part of the resistance value adjustment pattern uncut, and to manufacture circuit boards with stable resistance characteristics with a high yield.

[0071] 1, the product invention shows the state before trimming the resistance-adjustment pattern, but the thin-film resistor 10 that is actually produced is the state after the resistance-adjustment pattern has been trimmed and the resistance has been adjusted. Therefore, even in the state after the resistance-adjustment pattern has been trimmed, as shown in FIG. 5(a), at least a portion of the first mark 23 and the second mark 24 remain, so it is possible to recognize the state before trimming the resistance-adjustment pattern, and the state after trimming the resistance-adjustment pattern is also included in the scope of the invention.

[0072] 1 and the like is for coarse adjustment of the resistance value, and finer adjustment of the resistance value can be performed using a resistance value adjustment pattern for fine adjustment (not shown). In this way, when multiple types of resistance value adjustment patterns are arranged, the trimming start mark 20 shown in FIG. 3 can be applied to each resistance value adjustment pattern. [Industrial Applicability]

[0073] In the circuit board of the present invention, whether the position of the trimming start point is within the tolerance range can be determined by visually checking the trimming start mark, which improves work efficiency and reduces the risk of leaving any part of the resistance-adjustment pattern uncut, allowing for high yield manufacturing of circuit boards. The circuit board can be used for chip resistors, thin film resistor networks, etc. [Explanation of symbols]

[0074] 1: Thin film resistor 1a: Resistor pattern 1e, 1f: Wide section 2: Insulating substrate 3a~3d: Electrode 5: Folded end 6: Resistance adjustment pattern 9: Circuit board 10: Thin film resistor 20: Trimming start mark 22: Cropping area 23: First Mark 23a, 24a: Inside side 23b, 24b: outer edges 23c, 24c, 29a: Upper edge 23d, 24d, 30a: bottom edge 24: Second Mark 25:Connection part 28: Central connection part 29: Top edge connection 30: Bottom connection A: Trimming start point C: Acceptable range

Claims

1. A method for manufacturing a circuit board in which a resistor is formed on an insulating substrate, comprising: the resistor has a resistance value adjustment pattern, and a trimming start mark is formed in the vicinity of the resistance value adjustment pattern; the trimming start mark is composed of a first mark on a side closer to the resistance value adjustment pattern and a second mark formed on a side farther from the resistance value adjustment pattern, a trimming step of performing trimming from a predetermined trimming start point and cutting a part of the trimming start mark and the resistance value adjustment pattern, the trimming start point is set between the first mark and the second mark; a first mark formed on the first substrate and a second mark formed on the second substrate, the second mark being formed on the second substrate, and the second mark being formed on the first substrate;

2. The method for manufacturing a circuit board according to claim 1 , wherein the trimming start mark has a connecting portion that connects the first mark and the second mark.

3. 3. The method for manufacturing a circuit board according to claim 1, wherein the width of the first mark in a direction toward the second mark is wider than the width of the second mark.

Images