JP4741016B2 - Fuse resistor - Google Patents

Description

  The present invention relates to a fuse resistor that is formed of a resistor having a predetermined resistance value and operates as a fuse that protects 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.

According to the present invention, a fusible body that melts at a predetermined temperature is formed on an insulating substrate, a glass glaze layer is formed to cover the fusible body, a protective layer is formed to cover the glass glaze layer, A terminal resistor provided with a nickel plating layer and a solder plating layer is provided at both ends , and the protective layer is made of a material that softens at a temperature lower than the softening point of the glass of the glass glaze layer. The glass glaze layer is fired at a temperature lower than the softening point of the glass of the glass glaze layer, and the glass glaze layer is present in a state where the glass particles are not melted in the glass glaze layer covering the fusible body. It is a fuse resistor.

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

  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.

According to the fuse resistor of the present invention, the fusible element has covered with a glass glaze layer by glass particles on the glass glaze layer is present in a state which does not melt, reliably fusible element is fused at a predetermined temperature, good fuse performance is obtained, in which does not occur to reduce the impact at the time of fusing smoke like.

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, Al ₂ O ₃ , ZrO ₂ , and 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, the glass glaze layer 16 is fired at a temperature lower than the softening point of the glass glaze layer 16 of 600 ° C. or less, 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. In the fusible body 14 of the fuse resistor 10, the narrow portion 14 a is covered with the glass glaze layer 16. Therefore, when the narrow portion 14 a is melted during heat generation due to overcurrent , the glass particles in the glass glaze layer 16 are fused. It penetrates into the fusing part and suppresses the metal residue of the soluble body 14 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 rebonding 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, a reliable fuse performance is obtained by covering the narrow portion 14a of the fusible body 14 with the glass glaze layer 16 present in a state where the glass particles are not melted. It absorbs the impact of this and does not generate smoke.

  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 (6)

A fusible body that melts at a predetermined temperature is formed on the insulating substrate, a glass glaze layer is formed covering the fusible body, a protective layer is formed covering the glass glaze layer, and both ends of the fusible body In a fuse resistor provided with a terminal electrode in which a nickel plating layer and a solder plating layer are formed, and the protective layer is made of a material that softens at a temperature below the softening point of the glass of the glass glaze layer ,
The glass glaze layer is fired at a temperature lower than the softening point of the glass of the glass glaze layer, and is present in a state where glass particles are not melted in the glass glaze layer covering the fusible body. Fuse resistor. 2. The fuse resistor according to claim 1 , wherein the glass glaze layer is crystallized after the glass particles are melted at the time of melting the fusible body, and simultaneously the volume is reduced to form a space between the protective layer and the fuse resistor. vessel.   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 2, wherein the glass glaze layer is made of glass having a softening point of 820 to 900 ° C.

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