Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H37/00—Thermally-actuated switches
  • H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
  • H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
  • H01H37/761—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material with a fusible element forming part of the switched circuit
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H37/00—Thermally-actuated switches
  • H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
  • H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
  • H01H2037/768—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material characterised by the composition of the fusible material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
  • H01H85/02—Details
  • H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
  • H01H85/05—Component parts thereof
  • H01H85/055—Fusible members
  • H01H85/08—Fusible members characterised by the shape or form of the fusible member
  • H01H85/11—Fusible members characterised by the shape or form of the fusible member with applied local area of a metal which, on melting, forms a eutectic with the main material of the fusible member, i.e. M-effect devices
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49107—Fuse making

Definitions

• Fusible alloy element thermal fuse with a melt alloying element and method for producing a thermal fuse
• the invention relates to fusible alloy elements, in particular for use in thermal fuses, to protect modules, in particular control devices, in high-current applications against overheating.
• thermal fuse In order to protect electrical modules against overheating, irreversible thermal fuses are required, which interrupt (trigger) a current-carrying conductor if the ambient temperature is too high.
• the thermal fuses are designed in such a way that the tripping temperature is not reached as a result of a potentially occurring current flow, so that it is ensured that these can not be triggered by a high current, but only by an excessively high ambient temperature.
• a thermal fuse serves to provide an independent shutdown path for electrical modules which are at impermissibly high temperatures in the module, e.g. due to component failures, short circuits, e.g. due to external influences, malfunctions of insulating materials and the like. safely interrupts the flow of electricity.
• thermal fuses are usually based on the concept of a fixed spring (eg soldered leaf spring), in which the fixation dissolves (eg by melting) at a temperature effect, whereby the spring force Thermal fuse is opened.
• a fixed spring eg soldered leaf spring
• the fixation dissolves (eg by melting) at a temperature effect, whereby the spring force Thermal fuse is opened.
• a mechanical force is exerted on the connection point, which can lead to quality problems, especially with long operating times in the automotive sector, for example to a disruption of the solder joint.
• thermo fuse uses a conductive fusible material which begins to melt at a triggering temperature and thereby breaks a connection.
• the thermal fuse can be constructed by equipping a stamped grid with a fusible alloy element in a simple manner, without already causing a complete or partial melting of the fusible alloy element during the processing during production.
• a fusible alloy element in particular for the production of a thermal fuse.
• the fusible alloy element comprises a fusible element of a material fusible at a triggering temperature; and a carrier layer on a surface at least in a contacting region of the fusible alloy element.
• a melting temperature of the material of the carrier layer is higher than the triggering temperature, wherein the material of the carrier layer is chosen so that it goes into solid state in the molten material of the fusible element in solution.
• a fusible alloy element can be provided, which can be mounted more easily and reliably, since it has an increased resistance to high temperatures during soldering or other assembly process.
• the process temperature when assembling the fusible alloy does not immediately cause the fusible alloy to flow, because contraction of the melted material at the process temperature is prevented by lowering the surface tension. In other words, contraction of the molten material of the fuser, due to its surface tension, does not provide energy gain when the support layer is provided.
• the carrier layer is also designed so that it does not permanently hinder the flow of the fusible alloy element, since the material of the carrier layer in the material of the fusible element can go into solution.
• the material of the fusible element may contain tin and the material of the carrier layer may comprise copper.
• the melting element is cuboidal in order to provide a defined current distribution when used as a thermal fuse.
• the carrier layer can be formed continuously on the surface.
• the carrier layer can be formed on the surface and an opposite surface of the fusible element and in particular completely encloses the fusible element.
• the thickness and the material of the carrier layer may be chosen so as not to completely dissolve in the molten material of the fusible element with molten material of the fusible element for a certain period of time.
• Surface comprising at least one of the layers solder layer, corrosion protection layer and adhesion improvement layer.
• a thermal fuse is provided with a connection point on a stamped grid and with an above fusible alloy element which is fastened, in particular soldered, to the surface at the connection point.
• a method for producing a thermal fuse is provided, with the steps of applying a contact material, in particular a solder, to a connection point; the application of the above fusible alloy element, so that at least a portion of the carrier layer rests on the contact material; heating the contact material to or above its melting point such that the contact material bonds to the material of the carrier layer and the junction for a period of time limited by the length of time after which the material of FIG
• Carrier layer is completely dissolved in the region of the carrier layer in the molten materials of the fusible element and the contact material.
• FIG. 2 shows a further embodiment of the fusible alloy element according to the present invention
• Fig. 3c is a representation of the thermal fuse in a state after triggering.
• the fusible alloy element 1 essentially comprises a bar-shaped block with a fusible element 2 of a fusible material.
• the fusible element 2 contains a metal or other highly electrically conductive alloy or material through which a current flows when the Fusible alloy element 1 in a thermal fuse (see Figs 3a - 3c) is installed. Due to a sufficiently large cross-section of the fusible alloy element, a sufficiently low specific resistance and a good thermal connection to the environment, the fusible alloy element 1 heats up only slightly with respect to the environment even at the maximum permissible current flow.
• the melting point of the material of the fusible element 2 is chosen such that the block is subject to an increase in temperature due to malfunctions such as malfunctioning. Failures of electronic components, malfunctions of the insulating materials, short-circuits due to external influences above a melting temperature melts and thereby interrupts a current path that exists through the fusible alloy element.
• the fusible alloy element 1 is applied between two connection points that are otherwise electrically insulated from each other and, e.g. soldered there. When soldering the fusible alloy element 1 care must be taken that the
• Fusible alloy element 1 does not interrupt the current path during assembly, which can occur if a temperature would be applied which is equal to or greater than the melting temperature of the fusible element 2.
• a carrier layer 4 is provided, with which the fusible alloy element 1 is applied to the connection points or soldered there.
• the carrier layer 4 has a high melting point, which is higher than the melting point of the fusible material 2 and the solder used in the soldering process.
• the carrier layer 4 is furthermore provided from a material which slowly dissolves in the material of the melt element 2, ie can go into solution.
• the fusible element 2 materials with a sufficient tin content for example of more than 30%, more than 50%, more than 70% and particularly preferably more than 80% into consideration.
• the material of the carrier layer 4 copper or a copper alloy having a high copper content, such as more than 70%, may be used. Copper is advantageous because it already dissolves in solid state in liquid tin, the temperature of which corresponds to its melting temperature, at about 10 ⁇ m / min, whereby this value approximately doubles for every 10 K increase in temperature above the melting temperature.
• Other material systems for the materials of the fusible element 2 and the carrier layer 4 are also possible.
• a conventional solder is used, for example, the same material as the material of the fusible element 2.
• the fusible element 2 of the fusible alloy element 1 melts completely or partially and the material of the carrier layer 4 begins to be in the materi - To dissolve al of the molten melting element 2.
• the soldering process should be completed before the carrier layer is completely dissolved. As long as the carrier layer 4 has not yet completely settled in the molten melting element. has dissolved, it prevents the fusion of the fusible alloy element 1 on one or more of the connection points by reducing the surface tension.
• the thickness of the carrier layer 4 and the duration of the soldering process for attaching the fusible alloy element 1 at the connection points is to be selected such that only part of the carrier layer 4 dissolves, so that the current path is not interrupted despite melting or melting of the fusible element 2.
• the carrier layer 4 remaining after the soldering process during mounting dissolves in the molten material of the fusible element 2, and the fusible alloy element 1 interrupts the current path by exposing at the junctions portions of the molten material, e.g. drop-shaped due to the surface tension of the molten material attaches.
• the delay of the response at a temperature increase above the melting temperature of the melting element 2 should be as short as possible.
• FIGS. 1 a to 1 e show various configurations of the fusible alloy element 1. As shown in FIG. 1 a, the fusible alloy element 1 has a fusible element 2 on which the carrier layer 4 is applied on one side. The carrier layer 4 is on the side of
• the carrier layer 4 is not applied flatly on the surface of the fusible element 2 with which the fusible alloy element 1 is mounted, but only on the areas which are to be connected to the connection points. That the carrier layer 4 is e.g. interrupted in a central area. However, a continuous support layer is on the opposite surface and / or on a side surface (plane of representation of the figure) to effect the effect of preventing the contraction of the molten material of the fusible element.
• carrier layers 4 can be provided on both sides of the fusible element 2 (or on two or more than two different surfaces extending between the contact points of the fusible alloy element 1) in order to be fully fused of the fusible element 2 and a subsequent dissolution of the material of the carrier layer 4 in the material of the fused fusible element 2, triggering of the thermal fuse formed by the fusible alloy element 1. Furthermore, according to the embodiment of FIG. Id, provision can be made for the melting element 2 to be completely surrounded by carrier layers 4, so that outflow of the material of the melting element 2 out of the region between the carrier layers 4 opposite the surfaces can be avoided.
• FIG. 1e based on the embodiment of FIG. Id, it is shown that, in addition to the carrier layer, one or more further layers can also be provided, which accordingly perform an additional function.
• a section of the fusible alloy element 1 of Fig. Ie is shown for example in Fig. 2. There one recognizes that on the melting element 2 on the one hand, the carrier layer 4 and an additional layer 5 is applied.
• the additional layer 5 may be, for example, a solder layer, which provides an additional provision of a solder paste and the like. makes it superfluous for soldering the fusible alloy element 1 between the connection points. A soldering of the fusible alloy element 1 can then be done by placing the fusible alloy element 1 on the connection points and a corresponding heating.
• the additional layer 5 may additionally or alternatively constitute an oxidation protection layer for the carrier layer 4 in order to create a higher corrosion resistance. fen. Possible materials for this are eg Entec or SnAg-Cu.
• the additional layer 5 may alternatively or additionally constitute an adhesion enhancing layer, e.g. Ni or Au, in order to facilitate gluing or bonding of the fusible alloy element 1 to the connection point in an alternative application form.
• the or one of the additional layers may contain a flux.
• the materials of the one or more additional layers are chosen so that they also go into solution during the melting of the fusible element 2 therein, or melt or evaporate due to the process temperature.
• FIGS. 3a and 3b a mounting process for a thermal fuse is outlined.
• FIG. 3 a shows a process state which shows a fusible alloy element 1 of the embodiment of FIG. 1 a shortly before it is placed on connection points 6 of line regions 9 of a stamped grid 7.
• the connection points 6 of the stamped grid 7 are provided with a solder paste 8.
• the fusible alloy is placed and then the solder paste 8 is heated above its melting temperature.
• the melting element 2 also heats up and the carrier layer 4 of the fusible alloy element 1 is dissolved in the soldering paste 8 as well as in the fusible element 2, as far as the fusible element 2 is also melted.
• the carrier layer is thinner at points at which the fusible element 2 is soldered at the connection points than at the remaining regions.
• the thickness of the carrier layer 4 and the materials the melting element and the carrier layer 4 are chosen so that a reliable fastening of the fusible alloy element 1 at the connection points can be achieved by, for example, soldering, without the carrier layer 4 completely dissolving in the molten part of the fusible element 2.
• the reliability of the soldering process would be impaired, since in this case an interruption of the current path through the fusible alloy element 1 of the thermal fuse can occur.
• the thickness is limited by the fact that in the case of triggering the material of the carrier layer 4 in the molten material of the melting element as completely as possible in a short time, for example in 1 to 10 seconds, in solution. Due to the thickness, the inertia of the thermal fuse can thus be adjusted.
• Fig. 3c the thermal fuse is shown after a triggering event in which the fusible alloy has melted due to a high ambient temperature and the carrier layer 4 has dissolved in the molten fusible element 2. Due to the surface tension, portions of the molten fusible alloy are referred to the lead regions 9, where they contract to droplets due to their surface tension, respectively. Due to the surface tension and the affinity of the molten material of the fusible member 2 to contract on the lead portions 9, the molten material of the fusing member is drawn out of the region between the lead portions 9 and separated there.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Fuses (AREA)

Applications Claiming Priority (2)

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• 2007
  • 2007-03-26 DE DE102007014334A patent/DE102007014334A1/de not_active Ceased
• 2008
  • 2008-02-01 EP EP08708553A patent/EP2126950A1/de not_active Withdrawn
  • 2008-02-01 JP JP2010500158A patent/JP2010522420A/ja active Pending
  • 2008-02-01 WO PCT/EP2008/051244 patent/WO2008116681A1/de active Application Filing
  • 2008-02-01 US US12/593,120 patent/US20100176910A1/en not_active Abandoned
  • 2008-02-01 CN CN2008800098356A patent/CN101641758B/zh not_active Expired - Fee Related

Non-Patent Citations (1)

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