JP2010244817A - Fuse resistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuse resistor having an excellent response of a blowout action and a high reliability. <P>SOLUTION: The fuse resistor is provided with a fuse element 14 which blows out at a predetermined temperature formed on a surface of an insulated substrate 12 and a glass glaze layer 16 having a high melting point glass particle covering the fuse element 14. A protective layer 18 is formed for covering the glass glaze layer 16. On both end parts of the fuse element 14, there is provided a terminal electrode 20 with a nickel-plated layer and a solder-plated layer formed. The protective layer 18 is composed of a material which is softened at a temperature of a softening point of the glass of the glass glaze layer 16 or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuse resistor made of a resistor having a predetermined resistance value and operating as a fuse for protecting a circuit by fusing against a predetermined overcurrent.

  Conventionally, in an electronic circuit of various electronic devices, a fuse that cuts off a current by blowing a resistor when a current exceeding a specified value flows in the circuit in order to protect circuit elements from overheating and damage due to overcurrent. A fuse resistor having a function is mounted.

  In this fuse resistor, as disclosed in Patent Document 1, a thick film fuse is printed on an insulating ceramic substrate, and thick film electrodes are printed on both ends. And low melting glass is printed and formed so that a fuse and a part of electrode of both ends may be covered. The low melting point glass has a thickness of about 750 μm. This resists the impact and absorbs it when the fuse material is blown.

  Moreover, since the protective glass layer which covered the fuse resistor is baked after forming a fuse element, the fuse resistor disclosed by patent documents 2-6 uses the low melting glass of 660 degrees C or less in general. It is.

US Pat. No. 5,453,726 JP 2003-234057 A JP 2003-249403 A JP 2004-200506 A JP-A-8-31300 JP-A-8-102244

  However, in the case of the fuse resistor disclosed in Patent Document 1 of the background art, it is difficult to form the protective glass by forming a thick protective glass layer of about 750 μm, and the thickness of the fuse resistor increases. It was a thing.

  Further, in the case of the fuse resistors disclosed in Patent Documents 2 to 6, since the protective glass layer is a low-melting glass, the state of the state after being printed on the surface of the fuse resistor and melted and solidified by firing. Since it is a glass layer, it has a problem that it melts easily when the fuse resistor is blown, and it takes a long time to reliably cut off the blown portion of the fuse resistor, resulting in poor response of the operation.

  The present invention has been made in view of the above-described background art, and an object of the present invention is to provide a fuse resistor with good responsiveness of fusing operation and high reliability.

  In this invention, a soluble body that melts at a predetermined temperature is formed on the surface of the insulating substrate, a glass glaze layer having particles of a high melting point glass is formed covering the soluble body, and the glass glaze layer is covered and protected. The fuse resistor is provided with a terminal electrode in which a nickel plating layer and a solder plating layer are formed on both ends of the fusible body.

  The protective layer is formed to a thickness of 300 to 400 μm. Furthermore, the glass glaze layer is formed thinner than the protective layer. Preferably, the glass glaze layer has a thickness of 50 to 150 μm.

  The glass glaze layer is made of glass having a softening point of 820 to 900 ° C. Furthermore, the said glass glaze layer is baked at the temperature of 530-600 degreeC.

  The glass glaze layer is one in which glass particles are crystallized at the time of melting the fusible body, and at the same time the volume is reduced to form a space between the glass glaze layer and the protective layer.

  According to the fuse resistor of the present invention, by covering the fusible body with the glass glaze layer, the fusible body is surely blown at a predetermined temperature, a good fuse performance is obtained, and no smoke is generated at the time of fusing. .

It is a top view of the fuse resistor of one Embodiment of this invention. It is AA sectional drawing of FIG.

  An embodiment of the present invention will be described below with reference to the drawings. In the fuse resistor 10 of this embodiment, a fusible body 14 which is a resistor in which a narrow portion 14a of a current path is formed is formed on the surface of an insulating substrate 12 made of ceramics such as alumina.

On the narrow portion 14a of the fusible body 14, a glass softening layer 16 having a high softening point is formed. The glass glaze layer 16 is a glass ceramic made of CaO ₂ , Al ₂ O ₃ , ZrO ₂ , SiO ₂ . The glass glaze layer 16 is made of glass having a softening point of 800 ° C. or higher, preferably 820 to 900 ° C. The glass glaze layer 16 is present in a state where glass particles are not melted, and the glass glaze layer 16 is formed to a thickness of about 50 μm or more, preferably 50 to 150 μm, more preferably about 100 to 150 μm.

Further, a protective layer 18 that covers the glass glaze layer 16 and covers the entire narrow portion 14a is formed. The protective layer 18 is thicker than the glass glaze layer 16 and has a thickness of 500 μm or less, preferably about 300 to 400 μm. The component of the protective layer 18 is made of SiO ₂ , B ₂ O ₃ , ZnO, and is a glass whose softening point is lower than the softening point of the glass glaze layer 16.

  Terminal electrodes 20 are respectively formed at both ends of the insulating substrate 12. A nickel plating layer and a solder plating layer such as Sn / Pb are formed on the surface of the terminal electrode 20 to constitute an electrode of a chip-type fuse resistor.

  Next, the manufacturing process of the fuse resistor of this embodiment will be described. First, the fusible body 14 is formed on the insulating substrate 12. The fusible body 14 is formed of a metal material paste of Cu, Ag, Au, or Al into a predetermined shape by screen printing or the like. And it bakes at 500-600 degreeC, and forms a thick film resistor.

  Next, the glass glaze layer 16 is formed by screen printing or the like, and the narrow portion 14a of the fusible body 14 is covered. In this state, baking is performed at a temperature of 600 ° C. or lower, preferably about 530 to 600 ° C. Thereafter, the protective layer 18 is similarly printed and baked. Since the softening point of the protective layer 18 is lower than that of the glass of the glass glaze layer 16 and is preferably formed at as low a temperature as possible, the protective layer 18 is fired at a temperature of about 500 ° C.

  Further, a nickel plating layer and a solder plating layer are sequentially formed on the terminal electrodes 20 at both ends, thereby completing the fuse resistor 10.

  Next, the function of the fuse resistor 10 of this embodiment will be described. Since the fusible body 14 of the fuse resistor 10 is covered with the glass glaze layer 16, the narrow portion 14a is covered with the glass glaze layer 16. Therefore, when the narrow portion 14a is melted during heat generation due to overcurrent, glass particles can enter the melted portion. The metal residue of the solution 14 is suppressed to ensure fusing. Further, the glass particles are softened by the amount of heat at the time of fusing, blocking the fusing part, and preventing recombination of the fusing part due to metal residues.

  Furthermore, since the glass glaze layer 16 has a high softening temperature of 800 ° C. or higher and a film thickness of 50 μm or more, preferably 100 μm or more, the glass particles are crystallized after melting when melted. The volume is reduced and a space is formed between the protective layer 18 and absorbs an impact at the time of fusing. Thereby, the protective layer 18 is destroyed, and fuming due to fusing does not leak out of the protective layer 18.

  Moreover, when the protective layer 18 is formed to a thickness of about 300 to 400 μm, the buffering effect is surely exhibited even when the glass glaze layer 16 is broken by an impact caused by an overcurrent more than expected. Therefore, when the protective layer 18 is thinner than the above thickness, there is no buffering effect against damage to the glass glaze layer 16 due to overcurrent, and there is a possibility that problems such as breakage of the protective layer 18 and smoke generation may occur. On the other hand, when the protective layer 18 is thicker than the above-mentioned thickness, it can withstand overcurrent, but there are problems such as difficulty in forming a print, increasing the thickness of the element, and restricting the attachment site.

  Further, since the terminal electrode 20 of the fuse resistor 10 has a nickel plating layer formed on the surface thereof, a barrier made of nickel is formed in a state where an external lead wire or the like is connected, and an electrode using Ag glaze. In comparison with this, solder erosion in the process is prevented.

  According to the fuse resistor 10 of this embodiment, by covering the narrow portion 14a of the fusible body 14 with the glass glaze layer 16, a reliable fuse performance is obtained, and no smoke is generated when blown.

  The fuse resistor of the present invention is not limited to the above embodiment, and the fusible body is printed and formed by plating a metal of the fusible body material in a predetermined shape on the insulating substrate. It may be formed. Furthermore, a thin film resistor formed by sputtering or the like of these metal materials may be used depending on the application.

DESCRIPTION OF SYMBOLS 10 Fuse resistor 12 Insulating substrate 14 Soluble body 14a Narrow part 16 Glass glaze layer 18 Protective layer 20 Terminal electrode

Claims (8)

  A soluble body that melts at a predetermined temperature is formed on the surface of the insulating substrate, a glass glaze layer having particles of high-melting glass is formed covering the soluble body, and a protective layer is formed covering the glass glaze layer. The fuse resistor is characterized in that a terminal electrode on which a nickel plating layer and a solder plating layer are formed is provided at both ends of the fusible body.   The fuse resistor according to claim 1, wherein the protective layer is made of a material that softens at a temperature equal to or lower than a softening point of the glass of the glass glaze layer.   The fuse resistor according to claim 2, wherein the protective layer is formed to a thickness of 300 to 400 μm.   The fuse resistor according to claim 3, wherein the glass glaze layer is formed thinner than the protective layer.   The fuse resistor according to claim 4, wherein the glass glaze layer has a thickness of 50 to 150 μm.   The fuse resistor according to claim 5, wherein the glass glaze layer is made of glass having a softening point of 820 to 900 ° C.   The fuse resistor according to claim 6, wherein the glass glaze layer is fired at a temperature of 530 to 600 ° C. 7. 8. The fuse resistor according to claim 7, wherein the glass glaze layer is formed by crystallizing glass particles at the time of melting the fusible body and simultaneously reducing the volume to form a space between the glass glaze layer and the protective layer.

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