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  Current fuse and method of making the current fuseUSPTO Application #: 20070013472Title: Current fuse and method of making the current fuse Abstract: In order to provide a current fuse with high solderability without containing harmful materials, solder chips containing 30 to 60 percent by weight of zinc, 0.1 to 2 percent by weight of copper, 0.1 to 1 percent by weight of nickel, and the remainder percent by weight being tin, or further containing 0.01 to 0.5 percent by weight of aluminum are inserted into the interior of the electrodes before pressing the electrodes into the ends of the substrate of the fuse, the exterior of the electrodes is heated to melt the solder chips, thereby connecting between the electrodes and the fuse wire. (end of abstract) Agent: Smith Patent Office - Washington, DC, US Inventors: Satoru Kobayashi, Kazuyuki Kato USPTO Applicaton #: 20070013472 - Class: 337159000 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070013472. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional application of U.S. Patent Application Ser. No. 10/883,032 filed on Jul. 2, 2004, currently pending. The disclosure of U.S. Patent Application Ser. No. 10/883,032 is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a lead-free current fuse, which is suitable for electronic equipment and electronic components, for example, and a method of making the current fuse. [0004] 2. Description of the Related Art [0005] Various kinds of compact fuses, which are surface-mountable on a printed circuit board or the like, have been proposed. For example, a fuse in which a fuse element stretches in a hollow space within a rectangular case formed by attaching a ceramic casing main body and a lid has been disclosed in Japanese Patent Application Laid-Open No. 8-222117. [0006] In the case of this compact fuse, a fuse element and tin-lead solder, which has been adhered to the interior of metallic cap in advance, are soldered. [0007] On the other hand, tin-lead solder is essential for fabricating or assembling electronic equipment; however, it contains lead which is harmful to the human body and the like. Therefore, solder not containing harmful lead is desired by electronic equipment industries or related industries, and various kinds of lead-free solder have been proposed. For example, a lead-free solder alloy containing 7 to 10 percent by weight of zinc (Zn), 0.01 to 1 percent by weight of nickel (Ni), and the balance consisting of tin (Sn) has been described in Japanese Patent Application Laid-Open No. 9-94688. [0008] On the other hand, a solder material that has been disclosed in Japanese Patent Application Laid-Open No. 2000-15478 is developed considering environmental issues after discarding electronic equipment, and is a lead-free solder material containing tin, 3 to 18 percent by weight of zinc in proportion to that tin and a small amount of additives (e.g., nickel). [0009] However, when solder containing 10 percent by weight of tin and 90 percent by weight of lead is used to manufacture the fuse described in Japanese Patent Application Laid-Open No. 8-222117, a ceramic substrate absorbs heat generated when that solder melts. Therefore, a temperature to heat metallic caps must be set at approximately 400 degrees C., which is approximately 100 degrees C. higher than the melting point of solder. [0010] Such temperature degrades plating on the surface of metallic caps, resulting in deterioration of solderability when mounting a fuse on a substrate. [0011] On the other hand, the above-described lead-free tin-zinc-nickel solder is used for mounting a fuse on a substrate. That solder used in the interior of component causes a problem of deterioration of quality, such as break of a fuse element when the solder within each component melts in a reflow process when mounting the fuse on the substrate. SUMMARY OF THE INVENTION [0012] The present invention has been developed in view of the above-described problems, and aims to provide a current fuse, which has solderability suitable for electronic equipment and electronic components, and does not have an adverse influence on the environment including the human body, and a method of manufacturing the current fuse. [0013] The present invention has a configuration to achieve the above-described objectives. In other words, a current fuse includes a fuse wire and electrodes which are soldered using lead-free solder, wherein the lead-free solder contains at least 30 to 60 percent by weight of zinc, 0.1 to 2 percent by weight of copper, and the remainder percent by weight of tin. [0014] Furthermore, a current fuse includes a fuse wire and electrodes which are soldered using lead-free solder, wherein the lead-free solder contains at least 30 to 60 percent by weight of zinc, 0.1 to 1 percent by weight of nickel, and the remainder percent by weight of tin. [0015] Furthermore, a current fuse includes a fuse wire and electrodes which are soldered using lead-free solder, wherein the lead-free solder contains at least 30 to 60 percent by weight of zinc, 0.1 to 2 percent by weight of copper, 0.1 to 1 percent by weight of nickel, and the remainder percent by weight of tin. [0016] Furthermore, a current fuse includes a fuse wire and electrodes which are soldered using lead-free solder, wherein the lead-free solder having any one of the above-described composition further contains 0.01 to 0.5 percent by weight of aluminum. [0017] Furthermore, a current fuse, including: a fuse wire; a container for the fuse wire; and cap electrodes that are attached to both ends of the container; wherein the fuse wire is soldered to the electrodes using lead-free solder that is provided in the interior of the electrodes, and the lead-free solder has any one of the above-described compositions. [0018] Even further, a current fuse includes a fuse wire and electrodes which are soldered using lead-free solder, wherein the lead-free solder contains at least 30 to 60 percent by weight of zinc and the remainder percent by weight of copper and tin. [0019] In addition, when manufacturing a current fuse, a fuse wire and electrodes are soldered using lead-free solder at a temperature between a solid phase temperature and a liquid phase temperature of the lead-free solder. Alternatively, a fuse wire and electrodes are soldered in an atmosphere of oxygen using lead-free solder. BRIEF DESCRIPTION OF THE DRAWINGS [0020] FIG. 1 is an exploded view of a chip-type fuse according to an embodiment of the present invention; Continue reading... Full patent description for Current fuse and method of making the current fuse Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Current fuse and method of making the current fuse patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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