JP4906100B2 - Circuit board having a resistor for current detection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board preparing a resistor for detecting a current having excellent heat-dissipating property and mechanical strength and being capable of being used by a large power and firmly joining the resistor with an electrode pattern. <P>SOLUTION: The circuit board has a base board 11, a circuit pattern 15c consisting of a metal plate containing at least a pair of the electrode patterns 15a and 15b formed on the board 11 through an adhesive layer 12 and the resistor 16 consisting of a resistance metal plate arranged between the electrode patterns 15a and 15b. The resistor 16 and the electrode patterns 15a and 15b are fixed by a welding, a clad or a thermal diffusion. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a circuit board on which various electronic components including a current detection resistor capable of detecting a large current with high accuracy are mounted.

Conventionally, there has been known a metal plate resistor in which electrode plates such as copper are provided at both ends of a metal plate resistor such as a copper nickel alloy and a plating layer is provided on the electrode plate. These metal plate resistors are usually mounted on a circuit board using solder (for example, Patent Document 1).
JP 2002-184601 A

  In a current detection resistor using a metal plate resistor, it is necessary to flow a large current through the resistor in order to detect a current flowing through a minute resistor with high accuracy. Become. When a so-called glass epoxy board is used as the base material for the circuit board, the heat dissipation is poor, so the resistor for detecting current is relatively large (for example, 6.4 mm x 3.2 mm to 12.0 mm x 6.0 mm) Need to use.

  On the other hand, when a circuit board (for example, an aluminum board) based on a metal material with good heat dissipation is used, stress due to thermal contraction of the circuit board and further thermal or electrical load are applied, and bonding by soldering The part is easily destroyed. Therefore, a large size resistor is not preferable because it is easily affected by such stress, and there is a restriction that a small size resistor must be used.

  The present invention has been made based on the above-described circumstances, and has a current detection resistor that is excellent in heat dissipation and mechanical strength and can be used with high power, and the resistor is firmly attached to the electrode pattern. An object of the present invention is to provide a circuit board which is bonded to the circuit board.

A circuit board having a current detection resistor according to the present invention includes a base board, a circuit pattern made of a metal plate including at least a pair of electrode patterns formed on the board via an adhesive layer, and the electrode pattern. A resistor made of a resistive metal plate, and the resistor and the electrode pattern are fixed by welding, cladding, or thermal diffusion by abutting the resistor against the electrode pattern. Features. Further, in the method for manufacturing a circuit board having a current detection resistor according to the present invention, a hole is formed in a metal plate to be a circuit pattern, and the resistor is formed of a resistance metal plate across the hole or in the hole. The resistor is fixed to the metal plate by welding, cladding or thermal diffusion, the metal plate is bonded to a base substrate with an adhesive layer, and the metal plate is patterned to form a circuit pattern. Features.

  According to the present invention, the current detection resistor is provided in advance on the circuit board, and the resistor and the electrode pattern are fixed by a method such as welding, cladding, or thermal diffusion. Compared to bonding, it is more resistant to thermal, electrical and mechanical loads. Therefore, even when a metal base substrate is used, a large-sized resistor can be used, and use with high power is possible. In addition, since there is no need to mount a current detection resistor, variations in resistance value accuracy due to mounting errors are eliminated.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a circuit board having a current detection resistor according to an embodiment of the present invention. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same member or element.

  In this circuit board, a circuit pattern 15 made of a metal plate is formed on a metal base board 11 through an adhesive layer 12 made of a resin material. Here, an aluminum base substrate with good heat dissipation is used as the metal base substrate 11, and a copper plate having a thickness of about 0.06 mm is used as the circuit pattern 15 made of a metal plate. And as a part of the circuit pattern 15 which consists of metal plates, it has electrode patterns 15a and 15b, the resistor 16 which consists of resistance metal plates is arrange | positioned between these electrode patterns 15a and 15b, and the resistor for electric current detection is a circuit board. Is formed in advance. Here, the resistor 16 is a resistance metal plate such as a Cu—Ni alloy or a Ni—Cr alloy, and the thickness thereof is about 0.1 mm.

  Both ends of the resistor 16 are overlapped with part of the electrode patterns 15a and 15b, and are connected and fixed by a method such as welding or cladding. For welding, laser welding for irradiating with a laser beam, electron beam welding for irradiating with an electron beam, or the like is used. For the cladding, a diffusion bonding method using cold rolling or hot rolling is used. Note that a method of fixing using a solder material is excluded.

  The circuit pattern 15c is entirely covered with the solder resist 13 except for the terminal portion, and the electronic components 21, 22, 23, 24 are connected and fixed to a part of the terminal, and the other parts 25, 26 and the like are provided as empty terminals for external connection. The electrode patterns 15 a and 15 b are part of the circuit pattern 15 c and are covered with the solder resist 13 together with the resistor 16. In this embodiment, an example in which the electronic components 21, 22, 23, and 24 are mounted on the circuit board is illustrated. However, it is of course possible to ship as an empty terminal and mount the electronic component on the user side. .

  As the adhesive layer 12, an epoxy-based adhesive filled with an inorganic filler having high thermal conductivity is used. A metal plate to be a circuit pattern is bonded to the metal base substrate 11 with an adhesive, and then heat-cured to form the adhesive layer 12. After the metal plate is bonded to the metal base substrate 11 and heated and cured, the metal plate (Cu) is etched according to a predetermined pattern, thereby forming a circuit pattern which is a Cu wiring layer.

  The solder resist 13 is formed by applying a solder resist composition on the base substrate 11 on which the circuit pattern 15c is formed and performing a drying process, and then bringing the photomask on which the pattern of the solder resist opening is drawn into close contact with the solder resist. Exposure with ultraviolet light and development are performed to form openings. Further, the solder resist layer is cured by heat treatment. Next, the board | substrate with which the soldering resist layer was formed is immersed in a plating solution, and plating layers, such as nickel, are formed in the copper exposure part of a soldering resist opening part. Thereafter, a circuit board is formed by forming a solder layer in the opening of the solder resist layer.

  Therefore, in this circuit board, the current detection resistor is not mounted on the circuit board later, but is provided in advance on the circuit board, and the resistor 16 and the electrode patterns 15a and 15b are butt-matched or overlapped. It is formed into a shape and fixed by a method such as welding, cladding, or thermal diffusion. This makes it stronger against thermal, electrical, and mechanical loads than soldering. That is, in the past, a current detection resistor was mounted on a circuit board using a solder layer in the same manner as other electronic components such as ICs, but a large current flows through the current detection resistor as described above. The amount of heat generated is large, cracks are generated in the solder connection part due to thermal expansion, resistance value fluctuations occur, and in the worst case, disconnection may occur, but it is fixed by methods such as welding, cladding, and thermal diffusion instead of solder connection By doing so, even if the connection portion becomes strong and thermal expansion occurs, it is possible to prevent the connection portion from cracking and causing resistance value fluctuations.

  As a result, even when a metal base substrate such as an aluminum substrate is used, it is possible to mount a resistor for detecting a current of a large size resistor such as 6.4 mm × 3.2 mm to 12.0 mm × 6.0 mm. In addition, it has excellent heat dissipation and mechanical strength and can be used with high power. Further, since it is not necessary to mount the current detection resistor on the circuit board, there is an advantage that there is no variation in resistance value accuracy due to an error in mounting.

  Next, a manufacturing method of the first embodiment of the circuit board having the current detection resistor will be described with reference to FIG. In the first embodiment, as shown in FIG. 2A, the resistor 16 is fixed to the electrode patterns 15a and 15b by overlapping welding. The metal plate 15 to be a circuit pattern later uses a copper foil having a thickness of about 0.06 mm and forms a hole 31 by pressing (see FIG. 2B). Next, the resistor 16 is disposed in the hole 31 and both ends of the metal plate 15 and the resistor 16 are welded by laser beam welding to form an overlapping structure (see FIG. 2C). The resistor 16 is a resistance metal plate such as a Cu—Ni alloy or a Ni—Cr alloy, and has a thickness of about 0.1 mm. Both ends of the resistor 16 are welded to the metal plate 15. The size of the resistor or the size of the hole is set so that both sides of the resistor do not contact the metal plate.

  Next, the metal plate 15 in which the resistor 16 is disposed in the hole 31 is fixed to the metal base substrate 11 with the adhesive layer 12. The adhesive layer 12 includes an epoxy adhesive having electrical insulation properties, preferably an inorganic filler having high thermal conductivity, and has high heat dissipation properties, and is heated and cured after bonding the metal plate 15. Thus, the metal base substrate 11 to which the metal plate 15 is bonded is formed (see FIG. 2D). Then, the metal plate 15 is etched according to a predetermined pattern to form a circuit pattern. At this time, not only the electrode patterns 15a and 15b for connecting and fixing the resistor 16 but also the circuit pattern of the entire module substrate is formed (see FIG. 2E). Thereafter, the openings are covered with a solder resist, the openings are soldered, and the electronic components are mounted on the openings, thereby forming a circuit board on which the electronic components are mounted.

  Next, a manufacturing method of the second embodiment of the circuit board having a current detection resistor will be described with reference to FIG. This manufacturing method is the same as that of the first embodiment except that the resistor 16 is accommodated in the hole 31 (butt structure). That is, in this structure, the end face of the resistor 16 and the end face of the hole 31 of the metal plate 15 are abutted and fixed by welding or the like. When welding or the like, as shown in FIG. 3 (f), if a fixing member 17 is disposed at the joint between the metal plate 15 and the resistor 16, and this portion is irradiated with a laser beam or the like and welded, a stronger fixation is achieved. Is possible. The fixing material 17 may be made of the same material as the resistor 16 and the metal plate 15.

  Next, with reference to FIG. 4, the manufacturing method of the third embodiment of the circuit board having the current detecting resistor will be described. As shown in FIG. 4A, the structure is the same as that of the first embodiment shown in FIG. 2 except that both ends of the resistor 16 are overlapped and welded to the electrode patterns 15a and 15b. Are different as follows.

  First, a clad material is prepared by clad joining the resistance metal plate 16a and the metal plate 15 (see FIG. 4B). Then, the resistor metal plate 16a is etched by a predetermined pattern to form the resistor 16 (see FIG. 4C). In this case, since the resistor 16 is formed by etching, it is formed without machining as in the first and second embodiments, so that there is an advantage that the resistor can be easily formed with high accuracy. Note that a resistor of the same size may be welded to the metal plate regardless of etching. Then, the metal plate 15 on which the resistor 16 is formed is bonded and bonded to the metal base substrate 11 via the adhesive layer 12 with the resistor 16 facing downward (see FIG. 4D). Further, the metal plate 15 is etched to form a circuit pattern including the electrode patterns 15a and 15b (see FIG. 4E). Here, the circuit pattern includes all wiring patterns such as the empty terminals 25 and 26 and the connection parts of the electronic components 21, 22, 23, and 24 in FIG. 1. Further, a current detecting resistor in which both ends of the resistor 16 are fixed to the electrode patterns 15a and 15b by welding is formed.

  FIG. 5A shows a modification applicable to each of the above embodiments, in which the heat dissipating material 18 is arranged in advance on the resistor forming portion of the metal base substrate. As the heat dissipating material 18, for example, a ceramic plate having good thermal conductivity can be used, and the heat dissipating property can be improved. Further, as shown in FIG. 5B, a recess 19 may be formed in the base substrate 11. Thereby, good insulation between the metal base substrate 11 and the resistor 16 can be achieved.

  In the above embodiment, a metal base substrate such as an aluminum substrate has been described as an example of the base substrate. However, the present invention can be similarly applied to a glass epoxy substrate or the like. Moreover, although copper foil was demonstrated as an example of a metal plate, of course, a metal plate contains metal foil.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

(A) of the circuit board which has the resistor for electric current detection of one Embodiment of this invention is a perspective view, (b) is sectional drawing along BB line of (a). It is a figure which shows the manufacturing process of the circuit board which has the resistor for electric current detection of 1st Example, (a) is an expanded sectional view of the resistor for electric current detection, (b)-(e) in a manufacturing process It is a top view and sectional drawing along the BB line. It is a figure which shows the manufacturing process of the circuit board which has the resistor for electric current detection of 2nd Example, (a) is an expanded sectional view of the resistor for electric current detection, (b)-(f) is in a manufacturing process. It is a top view and sectional drawing along the BB line. It is a figure which shows the manufacturing process of the circuit board which has the resistor for electric current detection of 3rd Example, (a) is an expanded sectional view of the resistor for electric current detection, (b)-(e) in a manufacturing process It is a top view and sectional drawing along the BB line. (A) and (b) are the expanded sectional views of the resistor for electric current detection of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Metal base board | substrate 12 Adhesive layer 13 which consists of resin materials Solder resist 15 Metal plate 15a, 15b Electrode pattern 15c Circuit pattern 16 Resistor 16a Resistive metal plate 17 Fixing material 18 Radiating material 19 Recesses 21, 22, 23, 24 Electronic component 25 , 26 terminals

Claims (3)

A base substrate;
A circuit pattern made of a metal plate including at least a pair of electrode patterns formed on the substrate via an adhesive layer;
Comprising a resistive metal plate disposed between the electrode patterns,
The circuit board having a resistor for current detection, wherein the resistor and the electrode pattern are formed by abutting the resistor against the electrode pattern and fixed by welding, cladding, or thermal diffusion .   2. The circuit board having a current detecting resistor according to claim 1, wherein the base board is a metal base board. A hole is formed in the metal plate that becomes the circuit pattern,
A resistor made of a resistive metal plate is disposed across the hole or in the hole,
Fixing the resistor to the metal plate by welding, cladding or thermal diffusion;
Adhering the metal plate to the base substrate with an adhesive layer,
A method of manufacturing a circuit board having a resistor for current detection, wherein the circuit pattern is formed by patterning the metal plate.

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