JP2008053314A - Circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent microcracks from growing in a resistor at its high potential electrode side. <P>SOLUTION: The circuit board (10) comprises a high and low potential electrodes (2), (3) formed on an insulating board (1), and a resistor (4) formed between the elements (2, 3). The resistor (4) has an opening (5) for exposing a part of the board (1) to outside, and the opening (5) comprises a first opening (11) at one electrode (2), and a second opening (12) extending from the first opening (11) to the other electrode (3). A notch (13) extending from the first opening (11) to the other electrode (3) apart from the second opening (12) forms an ineffective region (15) for adjusting the resistance value of the resistor (4) without forming the end or the corner causing microcracks in the resistor (4) into the notch (13) at the one electrode side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a circuit board having a film resistor and a method for manufacturing the circuit board.

  As shown in FIG. 9, an insulating substrate (1), a pair of electrodes (2,3) formed on the substrate (1), and an electrode (2,3) are formed on the substrate (1). A circuit board (20) provided with the film-like resistor (4) formed is known. The resistor (4) is used as a resistor on the circuit, and the resistor (4) is irradiated with laser light to form a linear notch (13) on the upper surface (4a) of the resistor (4). By (trimming), it is adjusted to a desired resistance value. When the circuit board (20) is manufactured, the resistor (4) having a resistance value smaller than a desired resistance value is formed, and the length of the notch (13) is trimmed by the laser beam of the trimming device. Accordingly, the resistance value of the resistor (4) increases. In this way, the resistance value can be adjusted to form the resistor (4) having a highly accurate resistance value.

  The circuit board (20) is connected to one wiring conductor (7) connected to one end (4b) of the resistor (4) and the other end (4c) of the resistor (4). The other wiring conductor (8), one current pad portion (27) having a first terminal (21) electrically connected to one wiring conductor (7), and the other wiring conductor (8) The other current pad portion (28) having the second terminal (22) to be electrically connected, and the other having the third terminal (23) to be electrically connected to the one wiring conductor (7) A voltage pad portion (17) and the other voltage pad portion (18) having a fourth terminal (24) electrically connected to the other wiring conductor (8) are provided. In the circuit board (20) shown in FIG. 9, one wiring conductor (7) and one current pad part (27) constitute a high potential anode electrode (one electrode) (2), and the other wiring. The conductor (8) and the other current pad portion (28) constitute a cathode electrode (the other electrode) (3) that is separated from the anode electrode (2) and has a lower potential than the anode electrode (2).

  For example, in the four-terminal measurement method shown in FIG. 9 for measuring the resistance value of the resistor (4), each of the wiring conductors (7, 8) adjacent to both ends (4b, 4c) of the resistor (4) to be measured is measured. A voltage pad portion (17, 18) is connected to the inner end, and a pair of voltage measurement probes of the voltmeter (9) are brought into contact with the third terminal (23) and the fourth terminal (24). In addition, a constant current source device (which contacts the first terminal (21) and the second terminal (22) by connecting the current pad portion (27, 28) to each outer end of the wiring conductor (7, 8). Current is passed between the pair of current probes in 6). The voltage value of both ends (4b, 4c) of the resistor (4) is measured by a pair of voltage measurement probes of the voltmeter (9), and flows between the voltage value and the pair of current probes of the constant current source device (6). The resistance value of the resistor (4) is converted from the current value. While measuring the resistance value of the resistor (4) in real time, trimming the resistor (4) with a laser beam to form a notch (13) of a predetermined shape, thereby making the resistor (4) desired The resistance value can be adjusted.

  In this type of circuit board (20), when laser light irradiation is started or ended at a position close to the anode electrode (2) of the resistor (4), a notch portion (on the high potential anode electrode (2) side) The end of 13) is formed. When the notched portion (13) is formed by irradiating the resistor (4) with laser light, the resistor (4) around the notched portion (13) is thermally altered by the laser light. Further, when a current is passed through the resistor (4), the current density is concentrated at the end of the notch (13), and the end of the notch (13) of the resistor (4) is heated. As a result, microcracks may occur at the end of the notched portion (13) of the resistor (4) that has been thermally altered. When a microcrack occurs in the resistor (4) on the high potential side, there is a problem that the resistance value of the resistor (4) becomes unstable and the resistance value of the resistor (4) becomes unstable.

  In the circuit board (20) of FIG. 9, the open portion of the side surface (4e) of the resistor (4) where the wiring conductors (7, 8) are not formed is the laser beam irradiation start point (25a), and is indicated by a two-dot chain line. A laser beam is irradiated along the locus (25) to form an L-shaped notch (13). The L-shaped notch (13) and the side surface (4e) of the resistor (4) are bent by bending the laser beam locus (25) at a substantially right angle and bending the notch (13) toward the cathode electrode (3). An ineffective region (15) of the resistor (4) that does not become the current path (29) can be formed between the open portion and the open portion. Therefore, the cross-sectional area of the current path (29) of the resistor (4) from the anode electrode (2) to the cathode electrode (3) is reduced by the ineffective region (15) of the resistor (4) as shown in FIG. The resistance value of the resistor (4) can be increased by decreasing the resistance. According to the circuit board (20) of FIG. 9, the resistance value of the resistor (4) can be easily adjusted to a desired value.

  The end (13a) is formed in the notch (13) close to the cathode electrode (3) due to the end point (25b) of the laser light irradiation, but formed on the low potential cathode electrode (3) side. Even if a microcrack occurs in the resistor (4) around the end (13a), the resistance value of the resistor (4) does not become extremely unstable. A resistor trimming method for forming an L-shaped notch (13) in the resistor (4) by laser light is known, for example, from Patent Document 1 below.

Japanese Patent No. 2827608

  However, in the circuit board (20) of FIG. 9, the corner (13b) formed in the notch (13) forms the edge of the current path (29) on the anode electrode (2) side, and the resistor (4) As shown in FIG. 10, the current density increases at the resistor (4) around the corner (13b) of the notch (13) and heat is generated, and the anode electrode (2) side generates heat. There is a possibility that micro-cracks occur in the resistor (4), and the resistance value of the resistor (4) becomes unstable.

  Therefore, an object of the present invention is to provide a circuit board capable of forming an ineffective region in which a resistance value of a resistor is changed by forming a notched portion having no end or corner on the high potential electrode side, and a manufacturing method thereof. To do.

  The circuit board of the present invention is formed on the substrate (1) between the insulating substrate (1), the pair of electrodes (2, 3) formed on the substrate (1), and the electrodes (2, 3). A resistor (4). The electrode (2, 3) has one electrode (2) and the other electrode (3) which is separated from the one electrode (2) and has a lower potential than the one electrode (2). (4) has an opening (5) that exposes a part of the substrate (1) to the outside. The opening (5) has a first opening (11) formed on the one electrode (2) side, a width narrower than the first opening (11), and the first opening (11). ) To the other electrode (3) and a second opening (12). A notch (having a narrower width than the first opening (11) and spaced from the second opening (12) and extending from the first opening (11) toward the other electrode (3) 13) is formed. Due to the ineffective region of the resistor (4) formed by the first opening (11), the second opening (12) and the notch (13), one electrode (anode electrode) (2) to the other The cross-sectional area of the current path of the resistor (4) toward the electrode (cathode electrode) (3) can be reduced, and the resistance value of the resistor (4) can be increased. A first opening (11) is formed in the resistor (4) on the high potential side, and a second opening (narrower than the first opening (11) is narrower than the first opening (11). 12) and the notch (13) are each extended to the low potential side, so that the first opening (11), without forming an end or a corner in the notch (13) on the high potential side, The area of the ineffective region in which the resistance value of the resistor (4) is changed can be adjusted by the second opening (12) and the notch (13). Therefore, current flows through the resistor (4) along a smooth current path formed from the one electrode (2) to the other electrode (3) in the resistor (4), and the current density is locally increased. It is possible to prevent microcracks from occurring on the resistor (4) on the high potential side due to heat generation.

  The method for producing a circuit board of the present invention comprises a step of forming one electrode (2) and the other electrode (3) on an insulating substrate (1), and a step of forming the substrate (1) on the one electrode (2) side. A step of forming a resistor (4) having an opening (5) partially exposed to the outside on the substrate (1) between the electrodes (2, 3), and irradiating the resistor (4) with laser light The resistor (4) is formed in the resistor (4) by forming a notch (13) narrower than the opening (5) from the inside of the opening (5) toward the other electrode (3). Adjusting the resistance value. Since the notch (13) is formed toward the other electrode (3) with the inside of the opening (5) as the starting point of the laser beam, the end or corner of the notch (13) is formed on the one electrode (2) side. Without forming the opening, the opening (5) and the notch (13) or the opening (5), the notch (13) and the open part of the side surface (4d) of the resistor (4) (4) ) Ineffective regions for changing the resistance value can be formed. Also, unlike the notch (13) formed by the laser beam, the resistor (4) around the opening (5) does not undergo thermal alteration, so the trimming start point by the laser beam is the opening ( By setting the inside of 5), it is possible to prevent microcracks from occurring in the resistor (4) at the starting point of trimming by laser light. The opening (5) roughly adjusts the resistance value of the resistor (4), then forms a notch (13), and the length of the notch (13) determines the resistance (4) By changing the size of the ineffective area, the resistance value of the resistor (4) can be finely adjusted with high accuracy.

  Reliability that the resistance value of the resistor is kept constant for a long period of time by preventing the formation of the end or corner of the notch that causes local current density concentration of the resistor on the high potential side High circuit board can be provided.

  Embodiments of a circuit board and its manufacturing method according to the present invention will be described below with reference to FIGS. However, in FIGS. 1-8, the same code | symbol is attached | subjected to the part substantially the same as the location shown in FIG.9 and FIG.10, and the description is abbreviate | omitted. In addition to the resistor (4), a circuit element such as a semiconductor element or a chip capacitor is disposed on the actual substrate (1), but these are not shown for convenience.

  As shown in FIG. 1, in the circuit board (10) of the present embodiment, the resistor (4) has an opening (5) that exposes a part of the board (1) to the outside of the resistor (4). On the upper surface (4a). The opening (5) has a first opening (11) formed on the anode electrode (2) side, a width narrower than the first opening (11), and the first opening (11). And a second opening (12) extending toward the cathode electrode (3). The width direction of the resistor (4) is from one side surface (4d) to the other side surface (4e) of the resistor (4), and one side of the resistor (4) connected to one wiring conductor (7) When the length direction of the resistor (4) is from the end (4b) to the other end (4c) of the resistor (4) connected to the other wiring conductor (8), the first opening ( 11) is formed larger in the width direction than the second opening (12), and the second opening (12) is longer toward the cathode electrode (3) than the first opening (11). Largely formed in the vertical direction. Specifically, for example, if the width of the resistor (4) is 3.0 mm, the width of the first opening (11) is 0.9 mm or more and less than 3.0 mm. The width of the opening (12) is not less than 0.3 mm and less than 0.9 mm.

  The first opening (11) is formed in a substantially circular or elliptical shape. By forming the first opening (11) in a substantially circular or elliptical shape with no corners, a smooth current path (29) is formed as shown in FIG. 2 to prevent current concentration. it can. The first opening (11) is formed along the end (4b) of the resistor (4) on the anode electrode (2) side. The current flowing from the anode electrode (2) through the first opening (11) is distributed in the direction of both sides (4d, 4e) of the resistor (4), thereby concentrating the current in a part of the resistor (4). Can be prevented. The second opening (12) is formed substantially linearly from the first opening (11) to the cathode electrode (3). That is, the wide first opening (11) is formed on the high potential side, the narrow second opening (12) is formed on the low potential side, and the opening (5) is formed of the resistor (4 ) From one end (4b) to the other end (4c).

  In the present embodiment, the first opening (11) has a narrower width and is spaced apart from the second opening (12) toward the cathode electrode (3) from the first opening (11). A notch (13) to be stretched is formed. The notch (13) extends from the first opening (11) toward the cathode electrode (3) substantially in parallel with the second opening (12). The notch (13) is formed by trimming with a laser beam and is a groove in which the substrate (1) is not exposed to the outside or an opening from which the substrate (1) is exposed to the outside, and the resistance around the notch (13) by the laser beam The body (4) is thermally altered by the laser beam.

  The invalid region (15) of the resistor (4) formed between the first opening (11), the second opening (12), and the notch (13) does not contribute as a resistor and is invalid. By reducing the cross-sectional area of the current path (29) of the resistor (4) from the anode electrode (2) to the cathode electrode (3) by the region (15), the resistance value of the resistor (4) can be increased. it can. In the conventional circuit board (20), the corner (13b) is formed in the cutout part (13) on the high potential anode electrode (2) side, but in the circuit board (10) of the present embodiment, the anode electrode The first opening (11) is formed on the (2) side, and the second opening (12) and the notch are narrower than the first opening (11) from the first opening (11). (13) and extending to the low potential cathode electrode (3) side, respectively, by not forming an end or a corner in the notch (13) on the high potential side, the ineffective region to change the resistance value ( 15) can be formed. Therefore, as shown in FIG. 2, a smooth current path (29) is formed in the resistor (4) from the anode electrode (2) to the cathode electrode (3), and the resistor (4) is formed on the high potential side. The generation of microcracks can be prevented. As a result, the resistance value of the resistor (4) can be stabilized over a long period of time.

  FIG. 3 shows a circuit board (10) in which the first terminal (21) to the fourth terminal (24), the voltage pad section (17, 18), the constant current source device (6), and the voltmeter (9) are omitted. FIG. 4 is a partial sectional view taken along the line IV-IV in FIG.

  When manufacturing the circuit board (10), first, as shown in FIG. 4 (a), an insulating board (1) made of a material such as alumina, epoxy resin or ceramics is prepared. Masks (not shown) for forming the voltage pad portions (17, 18), the wiring conductors (7, 8), and the current pad portions (27, 28) are arranged on the surface of the substrate (1). On the substrate (1), there are a voltage pad portion (17, 18), an anode electrode (2) and a cathode electrode (3) each having a wiring conductor (7, 8) and a current pad portion (27, 28). It is formed. The voltage pad portion (17, 18), the wiring conductor (7, 8), and the current pad portion (27, 28) are printed on the substrate (1) with a metal paste mainly composed of copper and silver, for example, and burned By doing so, a thickness of about 0.01 to 0.02 mm is formed after combustion. Usually, other circuit patterns (not shown) are formed on the substrate (1) together with the wiring conductors (7, 8) and the current pad portions (27, 28).

  Next, a resistor (4) having an opening (5) exposing a part of the substrate (1) to the outside is formed on the substrate (1) between the electrodes (2, 3). In the present embodiment, the resistor (4) is formed by a known screen printing method, and the first opening (having a width wider than the notch (13) and formed on the anode electrode (2) side ( 11) and a second opening (12) having a narrower width than the first opening (11) and extending from the first opening (11) toward the cathode electrode (3). (4) Form simultaneously. As shown in FIG. 4B, a mask (19) is disposed on the substrate (1). The mask (19) has an opening (19a) in a region where the resistor (4) is to be formed on the substrate (1). As shown in FIG. 4 (c), the resistor (4) is formed, for example, by applying a resistance paste made of ruthenium oxide glass powder and an organic binder on the substrate (1) and burning it, so that it becomes 0 after combustion. It is formed with a thickness of about 0.01 mm.

  As shown in FIG. 4 (d), the resistance paste is not applied to the region covered with the mask (19) on the substrate (1), but the resistance paste is applied to the opening (19a) of the mask (19). When the mask (19) is removed and burned to be applied, the electrodes (2, 3) on the substrate (1) except for the first opening (11) and the second opening (12) A resistor (4) can be formed therebetween. When the opening is formed by the laser light, the resistor (4) around the opening is thermally altered by the laser light, but the first opening (11) and the second opening (12) are formed by the screen printing method. Therefore, when the current flows through the resistor (4) without any thermal alteration around them, the resistor (4) around the first opening (11) and the second opening (12) Does not generate microcracks. The first opening (11) is formed along the end (4b) of the resistor (4) on the anode electrode (2) side. When the laser beam is irradiated to the wiring conductor (7) or the current pad portion (27), the wiring conductor (7) or the current pad portion (27) is melted to form a hole, and the wiring conductor (7) or the current pad is formed. There arises a problem that current concentration occurs in the part (27). In the present embodiment, since the first opening (11) is formed by screen printing instead of laser light, the first opening (11) can be formed adjacent to the wiring conductor (7). .

  Subsequently, the resistor (4) is irradiated with a laser beam, and a notch (narrower than the first opening (11) is narrowed from the first opening (11) toward the cathode electrode (3). 13) is formed on the resistor (4). The resistor (4) is trimmed by a laser beam such as a YAG laser or an excimer laser emitted from a trimming device (not shown). The notch (13) is formed in a groove shape in which the substrate (1) is not exposed to the outside or a hole shape in which the substrate (1) is exposed to the outside by adjusting the intensity of the laser beam. As shown in FIG. 4E, the laser beam irradiation start point (25a) is located inside the first opening (11) and extends from the first opening (11) toward the cathode electrode (3). Thus, the trimming apparatus is controlled so that the locus (25) of the laser beam is formed. Therefore, the laser beam is first irradiated to the substrate (1) exposed in the first opening (11), but unlike the wiring conductor (7) or the current pad portion (27), the portion through which the current flows. Therefore, even if the substrate (1) is irradiated with a laser beam for a short time, an electrical failure due to thermal alteration or the like does not occur. Trimming with a laser beam is performed while measuring the resistance value of the resistor (4) using a four-terminal measurement method, but the four-terminal measurement method is the same as the conventional one, and detailed description thereof is omitted. Thereafter, the resistor (4) is covered with a protective film made of a glass coat (not shown), and other circuit patterns formed on the substrate (1) such as a semiconductor element (not shown) or a chip capacitor other than the resistor (4) Predetermined circuit components are mounted, and the circuit board (10) is completed.

  In the present embodiment, since the laser beam irradiation start point (25a) is formed in the first opening (11), the notch (13) is formed in a substantially straight line toward the cathode electrode (3). An end or a corner is not formed in the notch (13) on the anode electrode (2) side of the potential, and it is possible to prevent microcracks from occurring in the resistor (4) on the high potential side. Whereas the laser beam forms a notch (13) in the resistor (4) with a width of about 0.05 mm, the screen printing method has an opening (5) in the resistor (4) with a width of 0.1 mm or more. ). The first opening (11) and the second opening (12) are roughly adjusted so that the resistance value of the resistor (4) is lower than a desired resistance value, and a notch formed thereafter Depending on the length of the portion (13), the ineffective region (15) of the resistor (4) formed between the first opening (11), the second opening (12) and the notch (13) The resistance value of the resistor (4) can be finely adjusted with high accuracy by changing the size. Therefore, the resistor (4) can be used as, for example, a reference resistor or a current limit detection resistor on a hybrid IC (hybrid integrated circuit) circuit.

  The embodiment of the present invention is not limited to the embodiment shown in FIGS. 1 to 4 and can be changed. For example, the second opening (12) and the notch (13) are not formed in parallel, but the notch (13) is brought closer to the second opening (12) toward the cathode electrode (3). Also good. As shown in FIG. 5, the notch (13) may be inclined and connected to the second opening (12). Since the irradiation end point (25b) of the laser beam is formed in the second opening (12), a notch (13) having no end can be formed. Further, as shown in FIG. 6, the notch (13) may be bent on the cathode electrode (3) side and connected to the second opening (12). Although not shown, the second opening (12) and the notch (13) may be separated from each other toward the cathode electrode (3).

  The number of the notches (13) and the openings (11, 12) is not limited, and may be changed as appropriate. As shown in FIG. 7, at least a part of the notches (13) is spaced apart from the notches (13). Another notch (13) extending from one opening (11) toward the cathode electrode (3) is further formed instead of the second opening (12), and the first opening (11) and The ineffective region (15) of the resistor (4) may be formed by the two notches (13). FIG. 8 shows that the first opening (11) is formed adjacent to one end (4b) of the resistor (4) and the opening of the side surface (4d), thereby forming the second opening (12 ) Is omitted, and the ineffective region (15) of the resistor (4) is formed by the first opening (11), the notch (13), and the open portion of the side surface (4d) of the resistor (4). In the above embodiment, the first opening (11) is illustrated adjacent to the wiring conductor (7) along the end (4b) of the resistor (4), but the first opening (11) May be formed in the resistor (4) at a distance from the wiring conductor (7). The first opening (11) is not limited to a circle or an ellipse, and may be formed in another shape such as a square.

  When manufacturing the circuit board (10), the resistor (4) having the opening (5) may be formed on the substrate (1) by a known photolithography technique. A resistor (4) is formed on the substrate (1) by forming a photomask having an opening in a region where the resistor (4) is to be formed, and the resistor paste is applied to the substrate (1), and the resistor paste is burned. 4) can be formed. According to the photolithography technique, the opening (5) in which the peripheral resistor (4) is not thermally altered can be formed in the resistor (4), as in the screen printing method described above. Further, the first opening (11) can be formed in the resistor (4) adjacent to the wiring conductor (7). Further, the resistor (4), the wiring conductor (7, 8), the current pad portion (27, 28) and the voltage pad portion (17, 18) may be formed of the same material, and these may be formed simultaneously. Also good. In the above embodiment, the circuit board of the present invention and the manufacturing method thereof are applied to the hybrid IC, but may be applied to other electronic components such as a chip resistor.

  The present invention can be successfully applied to, for example, a current limit detection resistor that limits the current according to the determination of the reference potential of the amplifier and the detection result, and is particularly effective for a resistor having a resistance value of several ohms or less.

The top view which shows one Embodiment of the circuit board by this invention FIG. 1 is a plan view showing the current path of FIG. Simplified plan view of FIG. Partial sectional view taken along line IV-IV in FIG. The top view of FIG. 3 which inclined the notch part The top view of FIG. 3 which bent the notch part The top view of FIG. 3 which formed a pair of notch part 3 is a plan view of FIG. 3 with the second opening omitted. Plan view of a conventional circuit board FIG. 9 is a plan view showing the current path of FIG.

Explanation of symbols

  (1) ・ ・ Board, (2) ・ ・ Anode electrode (one electrode), (3) ・ ・ Cathode electrode (the other electrode), (5) ・ ・ Opening, (4) ・ Resistor, ( 4b) ・ ・ End, (11) ・ ・ First opening, (12) ・ ・ Second opening, (13) ・ ・ Notch, (15) ・ ・ Invalid area,

Claims (6)

An insulating substrate, a pair of electrodes formed on the substrate, and a resistor formed on the substrate between the electrodes,
The electrode has the one electrode and the other electrode spaced apart from the one electrode and having a lower potential than the one electrode,
The resistor has an opening that exposes a part of the substrate to the outside,
The opening has a first opening formed on the one electrode side, a width narrower than the first opening, and extends from the first opening toward the other electrode. A second opening,
A circuit having a narrower width than the first opening and spaced apart from the second opening and extending from the first opening toward the other electrode. substrate.   The circuit board according to claim 1, wherein the first opening is formed along an end of the resistor on the one electrode side.   The circuit board according to claim 1, wherein the first opening is formed in a substantially circular or elliptical shape. Forming one electrode and the other electrode on an insulating substrate;
Forming a resistor on the substrate between the electrodes, the resistor having an opening exposing a part of the substrate to the outside on the one electrode side;
The resistance value of the resistor is adjusted by irradiating the resistor with a laser beam and forming a notch in the resistor that is narrower than the opening from the inside of the opening toward the other electrode. And a process for manufacturing the circuit board. The step of forming the resistor includes
The method for producing a circuit board according to claim 4, comprising a step of simultaneously forming the resistor and the opening by screen printing or photolithography. The opening has a width wider than the notch and is formed on the one electrode side, and has a width narrower than the first opening and the first opening. And a second opening extending toward the other electrode having a lower potential than the one electrode,
The step of forming the notch in the resistor includes:
The resistance value of the resistor is adjusted by changing the size of the ineffective region of the resistor formed between the first opening, the second opening, and the notch according to the length of the notch. The method for producing a circuit board according to claim 4, comprising a step.

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