JP2004278856A - Initiator using thin-film bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an initiator using a thin-film bridge capable of firing powders efficiently without being influenced by the service environment, etc. <P>SOLUTION: The initiator is composed of a choke plug 4 having at least two electrode pins 2 and 3 insulated from each other and the thin-film bridge 5 mounted on the plug 4 and structured so that current is fed to the bridge 5 through the electrode pins 2 and 3, and thereby the bridge 5 is actuated to fire the powders 6 and 7. The bridge 5 is embedded in a recess 12 formed in the plug 4 in such a way as to be approximately flush with the pins 2 and 3 and the head 15 of the plug 4 and connected with the pins 2 and 3 using wire bonding, and one electrode pad of the bridge is connected with a header metal part 24 of the plug 4 by wire bonding 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an initiator used for igniting an explosive.
[0002]
As an initiator of this type, a thin-film bridge formed on a substrate made of ceramics or the like is fixed to an embolus with epoxy resin, polyimide, ceramics, or the like. Some of the bridges are electrically connected to electrode pins provided on the embolus with solder, wire bonding, conductive epoxy resin, or the like (for example, see Patent Document 1).
[0003]
Among these, the solder contains lead which leads to environmental pollution. Also, the solder needs to be melted at a high temperature. However, at this time, the bridge is exposed to a high temperature, and may be damaged by the heat and may not operate normally.
[0004]
In addition, when joined by conductive epoxy resin, when used as an initiator such as a gas generator for automobiles, it will be exposed to high-temperature heat generated under the hot summer sun for a long time, and the conductive epoxy resin The resistance value may change. In addition, even at the beginning of assembly, there is a problem that the resistance value is easily affected by the state of the electrode surface, and the initial resistance value varies greatly.
[0005]
In the case of wire bonding, the problems of solder and conductive epoxy resin can be solved.However, since the thin film bridge is fixed in a state of protruding above the embolus, the pressing force can be reduced when loading explosives. If it acts, there is a risk of disconnection. In particular, in the case of so-called uprighting, in which the end faces of the wires are joined upright as described in Patent Literature 1, the risk is remarkable.
[0006]
[Patent Document 1]
US Pat. No. 6,324,979B1
[Problems to be solved by the invention]
An object of the present invention is to provide an initiator using a thin-film bridge that can efficiently ignite an explosive without being affected by a use environment or the like.
[0008]
[Means for Solving the Problems]
According to an embodiment of the present invention, there is provided an initiator comprising: an embolus having at least two or more mutually insulated electrode pins; and a thin-film bridge attached to the embolus. An initiator for igniting an explosive by actuating the thin film bridge, wherein the thin film bridge is embedded in a recess provided in the plug so as to be substantially flush with the electrode pin and the head of the plug, and is bonded to the electrode pin by wire bonding. And one of the electrode pads of the thin film bridge is connected to the header metal part of the embolus by wire bonding.
[0009]
A thin film bridge is provided to be substantially flush with the electrode pins and the head of the embolus. In addition, when the thin film bridge and the electrode pin are connected by wire bonding by connecting using the peripheral surface of the wire in a state where the wire is laid down, instead of connecting with the end face of the wire, so-called horizontal connection However, the connection can be made with the wire loop height kept low. For this reason, even if the pressure which presses on a wire part acts, it becomes possible to prevent disconnection of a wire. Since at least one of the electrode pads is connected to the header metal part of the embolus by wire bonding, malfunction of the thin film bridge due to static electricity or the like can be prevented.
[0010]
Further, according to the initiator of the present invention, in the above-described invention, the material of the surface of the electrode pad of the thin film bridge is gold, aluminum, nickel, or titanium.
[0011]
Since the material of the surface of the electrode pad of the thin film bridge is gold, aluminum, nickel, or titanium, a current is reliably supplied to the thin film bridge by being connected to the electrode pin by wire bonding.
[0012]
Further, in the initiator of the present invention, in the above-described invention, the wire used for wire bonding is gold or aluminum and has a wire diameter of 10 μm to 500 μm.
[0013]
Since the wire used for wire bonding is gold or aluminum, it is possible to reliably supply current from the electrode pins to the thin film bridge. When the wire diameter is 10 μm to 500 μm, preferably 20 μm to 500 μm, and more preferably 100 μm to 500 μm, it is possible to more reliably supply a current from the electrode pins to the thin film bridge.
[0014]
Further, according to the initiator of the present invention, in the above-described invention, the loop height of the wire for wire bonding is 1 mm or less.
[0015]
Since the loop height of the wire is 1 mm or less, preferably 0.5 mm or less, and more preferably 0.2 mm or less, even if a pressing force is applied to the wire when loading explosives or the like, the wire is prevented from breaking. can do.
[0016]
Further, according to the initiator of the present invention, in the above-described invention, the step between the thin film bridge and the head of the electrode pin is 1 mm or less.
[0017]
By setting the step between the thin film bridge and the head of the electrode pin to 1 mm or less, preferably 0.5 mm or less, more preferably 0.2 mm or less, the loop height of wire bonding can be reduced. Further, it is possible to easily perform so-called horizontal mounting, in which the wires are connected using the peripheral surface of the wires in a laid state.
[0018]
Further, according to the initiator of the present invention, in the above-mentioned invention, the groove depth of the concave portion provided in the embolus is more than 0.2 mm and 1 mm or less.
[0019]
Since the groove depth of the recess provided in the embolus is more than 0.2 mm and 1 mm or less, when the thin film bridge is buried, the height can be substantially the same as the head of the embolus.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of an initiator according to the present invention will be described with reference to the drawings.
[0021]
In FIG. 1, the initiator 1 according to the embodiment includes an embolus 4 having a pair of mutually insulated electrode pins 2 and 3, and a thin film bridge 5 attached to the embolus 4. Then, a current is supplied to the thin film bridge 5 through the electrode pins 2 and 3, and the thin film bridge 5 is operated to ignite the explosives 6 and 7 loaded in the first tube 9.
[0022]
The embolus 4 is formed of a metal such as stainless steel, aluminum, copper, and iron. The pair of electrode pins 2 and 3 extending from the embolus 4 are made of a metal such as stainless steel, aluminum, copper, or iron, like the embolus 4. The electrode pins 2 and 3 are covered with an insulator 11 such as glass or resin in the embolus 4 and are insulated from each other. The end faces of the electrode pins 2 and 3 are provided so as to be substantially flush with the head 15 of the embolus 4.
[0023]
FIG. 2 is an enlarged plan view of a portion where the thin film bridge 5 is embedded in the concave portion 12 of the embolus 4. FIG. 3 is a diagram showing a cross section taken along line AA in FIG.
[0024]
As shown in FIGS. 2 and 3, the thin film bridge 5 is buried in a concave portion 12 formed in the embolus 4 and installed so as to be substantially flush with the embolus 4 and the electrode pins 2 and 3. The recess 12 has a groove depth h1 of usually more than 0.2 mm and 1 mm or less, preferably more than 0.2 mm and 0.75 mm or less, more preferably more than 0.2 mm and 0.5 mm or less. 5 is buried, the step height h2 from the head of the electrode pin (2, 3) is set to 1 mm or less, preferably 0.5 mm or less, more preferably 0.2 mm or less, thereby increasing the wire bonding loop height. H3 can be reduced. In addition, as shown in FIG. 3, so-called horizontal mounting in which the wires 8 are laid down and connected using the peripheral surface of the wires 8 can be easily performed. As described above, since the loop height h3 of the wire is usually 1 mm or less, preferably 0.5 mm or less, and more preferably 0.2 mm or less, the case where a pressing pressure is applied to the wire 8 at the time of loading an explosive or the like is used. Also, the wire 8 can be prevented from being broken, and the electrode pins 2 and 3 and the thin film bridge 5 can be reliably connected. In addition, as the wire 8, gold or aluminum is preferable. This makes it possible to reliably supply a current to the thin film bridge 5 from the electrode pins 2 and 3. In addition, by setting the wire diameter of the wire 8 to usually 10 μm to 500 μm, preferably 20 μm to 500 μm, and more preferably 100 μm to 500 μm, it is possible to more reliably supply a current to the thin film bridge 5 from the electrode pins 2 and 3. It becomes.
[0025]
As shown in FIG. 2, the wire 8 connecting the thin film bridge 5 and the electrode pins 2 and 3 is connected so as to be bridged over the surface of the electrode pad 21 of the thin film bridge 5. At this time, as described above, since the thin-film bridge 5 and the plugs 4 and the heads 15 of the electrode pins 2 and 3 are set in the recesses 12 of the plugs 4 so as to be substantially flush with each other, the wires 8 are so-called laid sideways. Can be joined. In this case, as shown by a dashed line (a line between A and A ′) in the figure, the wire 8 is connected to the header metal part 24 of the plug 4 from one of the electrode pads 21, thereby connecting the ground. Easy to take. The electrode pad 21 that is wire-bonded to the electrode pins 2 and 3 by the wire 8 is formed of a laminate 23 in which a reactive metal, for example, titanium, and a reactive insulator, for example, boron, are alternately laminated. It is made of gold, aluminum, nickel, titanium or the like formed on the surface by thermal evaporation or the like.
[0026]
As the thin film bridge 5, any of a heating resistor, a reactive bridge using a reactive substance, and a shock bridge can be used. These are formed on a Si substrate or a ceramic substrate such as Al ₂ O ₃ by a known technology such as a LIGA (Lithographie Galvan-formung, Abfprmung (microfabrication technique using X-ray)) process or sputtering. In particular, a reactive bridge is preferable in that it operates stably with small energy.
[0027]
As shown in FIG. 3, the reactive thin film bridge 5 shown in the present embodiment includes a reactive metal such as titanium formed on the surface of the substrate 22 and a reactive insulator such as boron. The bridge is composed of alternately laminated bridges 23 and electrode pads 21 formed of a conductive material such as metal covering the surface thereof. 2 and 3, the electrode pad 21 is located on the stacked body 23.
[0028]
Examples of the reactive metal used for the laminate 23 include aluminum, magnesium, and zirconium in addition to titanium. As the reaction insulator, there are calcium, manganese, silicon, and the like in addition to boron. When the thin film bridge 5 having such a stacked body 23 is activated by a current flowing through the bridge portion, the reactive metal reacts with the reactive insulator, and is released as hot plasma. And this plasma can ignite the loaded explosive efficiently.
[0029]
In the initiator 1 according to this embodiment, as shown in FIG. 1, first, after loading the explosives 6 and 7 into the first tubular body 9, the thin film bridge 5 is set in the concave portion 12 formed in the plug 4. Then, after being connected to the electrode pins 2 and 3 by wire bonding with the wire 8, it is fitted to the first tube 9. At this time, even if the embolus 4 is pressed against the explosive 6, the electrode pins 2 and 3 are buried in the thin film bridge 5 and the embolus 4 and the so-called horizontal wires as described above. Since they are connected by bonding, there is no possibility of disconnection or the like. After the plug 4 is fitted to the first tube 9 in this way, the first tube 9 is inserted into the second tube 10 and insert-molded in the holder 20. Thereby, it can be suitably used for an igniter for a gas generator used for various safety devices such as automobiles.
[0030]
In the initiator 1 configured as described above, when a current is supplied to the electrode pins 2 and 3, the thin-film bridge 5 is operated, and the explosives 6 and 7 can be ignited efficiently in units of several microseconds. Become.
[0031]
In addition, the initiator according to the present invention is not limited to the above-described embodiment, and can reliably connect the electrode pins 2 and 3 and the thin film bridge 5 by wire bonding. , 3 and the thin film bridge 5, an ASIC (Application specific integrated circuit) or the like may be interposed, and similarly, the connection may be made by wire bonding.
[0032]
【The invention's effect】
The initiator of the present invention is configured as described above, by embedding the thin film bridge in the embolus and installing it so as to be substantially flush with the electrode pin and the head of the embolus, by wire bonding called so-called horizontal mounting The electrode pin and the thin film bridge can be connected. For this reason, even if it is wire bonding, even if pressing stress etc. act on the wire part, it is possible to suppress the occurrence of disconnection of the wire, that is, the disconnection of conduction between the thin film bridge and the electrode pin. Become. In addition, it is possible to ignite explosive efficiently.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an example of an embodiment of an initiator according to the present invention.
FIG. 2 is a diagram showing a main part plane in which a part of FIG. 1 is enlarged.
FIG. 3 is a view showing a cross section taken along line AA ′ in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Initiator 2 Electrode pin 3 Electrode pin 4 Embolus 5 Thin film bridge 6, 7 Explosive 8 Wire 9 1st tube 10 2nd tube 11 Insulator 12 Depression 15 Head 21 Electrode pad 22 Substrate 23 Laminate 24 Header metal part

Claims (6)

The electrode pin (2, 3) comprising an embolus (4) having at least two or more mutually insulated electrode pins (2, 3), and a thin film bridge (5) attached to the embolus (4). An initiator for supplying an electric current to said thin film bridge (5) through said first member, and activating said thin film bridge (5) to ignite the explosive (6, 7);
The thin film bridge (5) is provided in a recess (12) provided in the plug (4) so as to be substantially flush with the electrode pins (2, 3) and the head (15) of the plug (4). It is embedded and connected to the electrode pins (2, 3) by wire bonding, and one of the electrode pads (21) of the thin film bridge (5) is wire bonded to the header metal part (24) of the plug (4). An initiator characterized by being connected by: The initiator according to claim 1, wherein the material of the surface of the electrode pad (21) of the thin film bridge (5) is gold, aluminum, nickel, or titanium. The initiator according to claim 1, wherein the wire (8) used for the wire bonding is gold or aluminum and has a wire diameter of 10 µm to 500 µm. The initiator according to claim 1, wherein a loop height (h3) of the wire (8) for the wire bonding is 1 mm or less. The initiator according to claim 1, wherein a step (h2) between the thin film bridge (5) and the head of the electrode pin (2, 3) is 1 mm or less. The initiator according to claim 1, wherein a groove depth (h1) of the concave portion (12) provided in the embolus (4) is more than 0.2 mm and 1 mm or less.

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