JP2004022290A - Structure for mounting chip-type thermal fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure for mounting a chip-type thermal fuse that can be automatically supplied and mounted at a specific position on a packaging structure without accompanying inconveniences such as disconnection in the fuse element of chip components. <P>SOLUTION: In the mounting structure of the chip-type thermal fuse, a leading section 13 of a lead member 11 in chip components is connected and joined to a wiring land 32 by pressure welding junction such as ultrasonic junction, when mounting the chip components 10 of an airtight package 20 for accommodating the fuse element 16 to a specific position on the packaging board 30 having the wiring land 32. Especially, in the chip components 10, a low melt point soluble alloy 14 having a flux film 15 is erected between the electrodes 12 of a lead member 11 fixed to an insulating case 22 in an airtight package 20, the opening of the insulating case 22 is covered with a cap 24 as the airtight package 20, and a low melt point substance is included between the leading section 13 of the lead member 11 and the wiring land 32. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a chip type temperature fuse used on a mounting substrate such as a printed wiring, and more particularly, to a chip component without causing a defect in a low melting point fusible alloy fuse element. The present invention relates to a mounting structure of an alloy type chip type thermal fuse mounted at a predetermined position on a mounting substrate.
[0002]
2. Description of the Related Art A thermal fuse for applying a flux to a low-melting-point fusible alloy to make the fusible alloy into a spherical shape at the time of melting is formed by welding and joining a low-melting-point fusible alloy between a pair of lead tip side electrodes. Be composed. The flux applied to the surface of the low-melting fusible alloy prevents the oxide film from interfering when the low-melting fusible alloy melts at the melting temperature, and forms the fusible alloy melted at a predetermined temperature into a spherical shape by surface tension. The electrical connection between the two electrode portions can be used for disconnection (see JP-A-06-243767 and JP-A-04-282523).
On the other hand, wiring bodies used in electronic devices have recently been manufactured using a high-speed mounting technology using an automated chip mounter due to the development of miniaturized components and high-density mounting technology. For example, a chip component of less than 1 mm square is used as a circuit component in a wiring body for a mobile phone by using an automatic supply system and a mounter device. From such demands, a temperature fuse of a thin type in which a low melting point fusible alloy is surrounded by an insulating material and having a thickness of less than 1 mm and a small type in which a fusible alloy is mounted on an insulating substrate is known. See JP-A-2-291624).
[0004]
In the mounting of a chip component as a wiring body, the above-mentioned chip type temperature fuse is provided with a lead lead-out portion extending outside the hermetic package. Solder mounted in position. However, during the soldering process, heat from the molten solder material is transmitted into the package component through the lead, and the fuse element may be melted and disconnected. In order to avoid such thermal fuse failures, the mounting of chip components depends on individual and careful hand soldering or requires careful work. Automated mounting including soldering similar to general chip components has been considered to be unsuitable for thermal fuses made into chip components because of the problems such as disconnection defects. For this reason, it has been difficult to reduce the mounting area to be soldered in the mounting operation of the chip component.
When a chip type temperature fuse is incorporated into a printed wiring body, there is a problem in a soldering operation using a solder material which is a fusible alloy in order not to cause a defect in a fuse element. Was needed to be applied. Therefore, in order to prevent the occurrence of failure of the fuse element in handling such chip components and to always exhibit the original function of the temperature fuse satisfactorily, a method of mounting the chip components on the mounting board by a method different from soldering. The proposal was desired.
Therefore, the present invention has been proposed in view of the above-mentioned drawbacks, and when mounting a chip component having a fuse element on a mounting substrate on which wiring lands are formed, a connection error or a failure of the fuse element is required. An object of the present invention is to provide a new and improved chip-type thermal fuse mounting structure by press-welding for preventing disconnection and damage.
Another object of the present invention is to provide a new and improved chip-type thermal fuse which can reliably and quickly mount chip components mounted between wiring lands on a mounting board without deteriorating a fuse element function. It is to provide a mounting structure.
[0008]
According to the present invention, there is provided a mounting structure of a chip type thermal fuse, comprising: a mounting substrate provided with wiring lands for mounting circuit components; and a low melting point fusible alloy of a fuse element between a pair of lead members. It is provided with a chip component that is erected and has a flux coating formed on its surface and then hermetically packaged. The lead portion of the pair of lead members and the wiring land of the mounting substrate are pressure-welded and mounted on the mounting substrate.
In the mounting structure of the chip type temperature fuse of the present invention, the lead parts of the pair of lead members are connected between the wiring lands of the mounting board by resistance welding, ultrasonic bonding, thermocompression bonding or the like. It is mounted on a mounting substrate by electromechanical coupling. Preferably, a chip component positioning means is formed on the mounting substrate, the wiring land and the lead member lead-out portion are formed substantially flat to form a desired L-shape, and a material having a low melting point is interposed. The lead-out part and the wiring land are welded by metal-to-metal bonding using ultrasonic waves, and are electrically and mechanically connected.
[0010]
DESCRIPTION OF THE PREFERRED EMBODIMENTS A chip type temperature fuse according to the present invention comprises a pair of lead members each having an electrode at one end, and a fuse element having a predetermined melting temperature bridged between the two electrodes. And an insulating case, wherein the insulating case is bonded with a cap and hermetically packaged, and the fuse element is made of a low melting point soluble alloy of tin (Sn), antimony (Sb), An alloy having two or more compositions selected from metal groups including cadmium (Cd), indium (In), lead (Pb), bismuth (Bi), silver (Ag), and copper (Cu). The fusing temperature is determined within the operating temperature range of 60 to 190 ° C. depending on the composition ratio. For example, a ternary alloy material containing Sn-Pb-Bi is used for a temperature fuse having an operating temperature of 98 ° C, and a binary alloy material of Sn-Pb is used for a temperature fuse having an operating temperature of 180 ° C. .
In mounting the chip component on the mounting board, the lead-out portion of the lead member is provided between the predetermined wiring lands on the mounting board without deteriorating the fuse element function by resistance welding, friction welding, thermocompression bonding. Then, they are pressure-bonded by ultrasonic bonding or the like, and are electrically and mechanically connected. The pressure welding is desirably an ultrasonic metal-to-metal bonding, which does not cause a problem with the low melting point fusible alloy of the fuse element. In addition, at the time of this bonding, preferably, not only the bonding strength between the lead portion of the chip component and the wiring land of the mounting board is increased by interposing a low-melting substance such as amorphous copper, indium, or a solder chip, In addition, thermal damage to the mounting board can be suppressed. At this time, plating can be performed on the surface of the lead member to facilitate the joining.
[0012]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mounting structure of a chip type thermal fuse according to an embodiment of the present invention will be described below in detail with reference to FIGS. The figure shows a mounting structure of a chip type temperature fuse including a chip component 10 constituting a printed wiring body and a mounting board 30 on which the chip component 10 is mounted. The chip component 10 leads out a part of a lead member 11 to the outside. The airtight package 20 made of a thermoplastic resin is mounted at a predetermined position on the mounting board 30, and is electrically and mechanically press-bonded between the pair of wiring lands 32 by ultrasonic metal-to-metal bonding. As shown in FIG. 2, the chip component 10 has a fuse element 16 made of a low melting point fusible alloy 14 having a flux coating 15 applied inside an airtight package 20 between the electrode portions 12 of a pair of lead members 11. The lead-out portions 13 of the pair of lead members 11, which are welded and bridged and extend to the outside of the resin package 20, are connected between the wiring lands 32 of the printed pattern formed on the mounting board 30 by ultrasonic waves. Joined to form a mounting structure of a chip type thermal fuse. Here, the lead member 11 is made of a plate-like conductor such as nickel, phosphor bronze, or iron, and is preferably adapted to a chip manta for automatically assembling a wiring body with chip components. On the other hand, a well-known chip mounter is used for supplying and mounting chip components at a predetermined position on such a mounting board. Therefore, the chip parts of the present invention are processed in the same manner as chip parts such as resistors and capacitors, and are used for mass production efficiency by automatic assembly work. After the chip components are mounted at predetermined positions, ultrasonic energy is applied to the lead portions 13 of the pair of lead members, and the electrical and mechanical metal-to-metal bonding with the wiring lands 32 is performed by short-time spot thermal compression. Done. Here, the lead member 11 formed in a flat plate shape is formed into a shape suitable for the chip mounter, for example, the lead portion 13 is formed into an L-shape. Further, by interposing a material having a low melting point such as amorphous copper, a solder chip, or a printed metal between the lead member lead-out portion 13 and the wiring land 32 of the mounting board, the weldability is improved. Thermocompression bonding such as laser, electric resistance welding, and ultrasonic bonding can be applied to the pressure bonding, and metal-to-metal bonding using ultrasonic waves for applying ultrasonic energy is particularly desirable.
In other words, the present invention provides a chip component 10 of an airtight package 20 in which an insulating case containing a fuse element 16 disposed between a pair of lead members 11 is sealed with a cap, and a wiring land on which the chip component is mounted. A pair of lead members 11 are formed integrally with an insulating case, and have an electrode portion 12 inside the insulating case and a lead-out portion 13 outside, and a wiring land 32 of the mounting substrate 30. This is a mounting structure of a chip-type thermal fuse formed by pressure-welding a lead-out portion and a lead portion 13. Here, the insulating case 22 and the cap 24 of the hermetic package 20 are each formed of a molded body of a thermoplastic resin, the lead-out portions 13 of the pair of lead members 11 are formed so as to be positioned on the wiring lands 32, and the electrode portions are formed. Numeral 12 is plated to make it easy to fuse with the fuse element 16. Preferably, the lead-out portion 13 of the lead member and the wiring land 32 of the mounting board are pressure-welded by ultrasonic metal-to-metal bonding, and a low melting point such as a metal foil, a printed metal, amorphous copper, or a solder chip is provided therebetween. The intervening material facilitates electromechanical coupling between the lead-out portion and the wiring land. In addition, positioning means such as depressions for arranging chip components may be formed on the mounting board, and the lead-out portion of the lead member may have an uneven surface to be joined. Further, a conductive adhesive such as a conductive plastic may be interposed between the lead-out portion 13 and the wiring land 32, so that the positioning can be more reliably achieved. The lead member is made of a plate-like conductor such as nickel, phosphor bronze, iron or the like, and its electrode portion or lead-out portion is plated to facilitate welding with a low melting point fusible alloy or wiring land. As shown, the lead-out portion 13 is arranged along the outer peripheral bottom surface of the hermetic package 20.
[0014]
The mounting structure of the chip type temperature fuse according to the present invention comprises a low melting point fusible alloy with a flux applied between the electrodes of a pair of lead members. The chip component is electrically and mechanically coupled by ultrasonic pressure bonding when mounted on a wiring land on a mounting board, so that automatic supply and mounting by a chip mounter can be performed in a wiring assembly operation. In particular, in mounting the chip type temperature fuse, the pressure welding technique using ultrasonic waves is used, so that the mounting operation can be performed reliably and easily without causing a defect in the temperature fuse. Further, application of ultrasonic metal-to-metal bonding is expected to have a practical effect such that the chip component is securely mounted at a predetermined position, which contributes to miniaturization and thinning of the wiring body, which contributes to stabilization of quality and improvement of reliability.
[Brief description of the drawings]
FIG. 1 is a partially cutaway plan view showing a mounting structure of a thermal fuse according to an embodiment of the present invention.
FIG. 2 is a side sectional view of a main part of a portion substantially along the center of FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Chip component 11 Lead member 12 Electrode part 13 Outgoing part 14 Low melting point fusible alloy 15 Flux coating 16 Fuse element 20 Airtight package 22 Insulation case 24 Cap 30 Mounting board 32 Wiring land

Claims (7)

An airtight package chip component in which a mounting board having circuit component mounting wiring lands and a low-melting-point fusible alloy having a flux coating on the surface laid between a pair of lead members are housed in an insulating case and sealed with a cap. Wherein the pair of lead members has an electrode portion inside and outside of the insulating case formed integrally, and a lead-out portion outside, and the wiring land of the mounting board and the lead-out portion of the lead member are joined by pressure contact bonding. A mounting structure of a chip type thermal fuse in which the chip component is mounted on a mounting board. The lead member has a lead-out portion made of copper, phosphor bronze, iron, nickel, or printed or plated thereon to facilitate welding by thermocompression bonding at the time of press-joining with the wiring land. The mounting structure of the chip-type thermal fuse according to claim 1. 3. The chip type thermal fuse mounting structure according to claim 1, wherein the pressure contact bonding between the lead portion of the lead member and the wiring land of the mounting substrate is an intermetallic connection by ultrasonic waves. 4. The mounting board according to claim 1, wherein said mounting board has a positioning means for properly arranging said chip parts, and a lead-out portion of said lead member is formed so as to fit between said wiring lands. Chip type temperature fuse mounting structure. 5. The mounting of a chip type temperature fuse according to claim 4, wherein the forming of the lead-out portion is carried out by accurately pressing and joining the contact surface of the mounting substrate with the wiring land as an uneven portion. Construction. A low-melting substance such as a printed metal, amorphous copper, or a solder chip is interposed between a lead portion of the lead member and a wiring land of the mounting board, so that metal-to-metal bonding by pressure bonding is accurately and easily performed. Item 6. A mounting structure of the chip type thermal fuse according to items 1 to 5. The wiring land of the mounting board is made of a metal foil, a printed electrode, a conductive adhesive or a conductive plastic, and a metal-to-metal joint between a lead member lead-out part of the chip component and an ultrasonic wave is facilitated. Item 7. A mounting structure of the chip type thermal fuse according to items 1 to 6.

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