JP2001052593A - Fuse and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuse avoiding a rapid break tendency, and allowing improvement in manufacturing property and adhesion of a fuse element, and provide a manufacturing method therefor. SOLUTION: In this manufacturing method, a polyimide film having a sputtered film formed by sputtering copper is thermocompression-bonded onto one side of a glass cloth resin substrate 2 to form a highly adhesive polyimide resin layer 3, then a laminated fuse element is formed by etching the sputtered film in a prescribed fuse pattern to form a highly adhesive first metal film 5, and forming a second metal film 6 by tin electroplating on the upper surface of the first metal film 5 through a third metal film 8 formed by nickel plating. Next, a protective layer 13 is formed such that the protective layer 13 covers a narrow part of the fuse element 7, and cross-sectionally U-shaped electrodes 11, 11 are formed in both end parts uncovered with the protective layer 13 from the fuse element 7 to the rear surface side. Thereby, the polyimide resin layer 3 prevents thermal dissipation to prevent a rapid fusion, and improves adhesion of the fuse element 7. This manufacturing method can improve a manufacturing property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuse for improving fusing performance and manufacturability, and a method for manufacturing the fuse.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a circuit board on which electric components are mounted at a high density in accordance with the demand for small and light electric devices, and various chip-like structures in which fuses are surface-mounted are known. ing.

[0003] The structure of this conventional chip-shaped fuse is known, for example, from Japanese Patent Publication No. 9-510824 as shown in FIG.

The fuse 20 described in Japanese Patent Application Laid-Open No. 9-510824 shown in FIG. 5 uses an epoxy resin plate or a polyimide resin plate reinforced with glass fiber or the like, which is used as a printed circuit board, as a support substrate 21. A predetermined fuse pattern made of a conductive film is formed on the support substrate 21.

[0005] This fuse pattern is formed by etching a copper foil provided on an epoxy resin plate or a polyimide resin plate used as a printed circuit board, removing the entire surface, and removing a metal such as copper from the epoxy resin plate. A predetermined fuse pattern is formed again on the surface of the plate or polyimide resin plate by a conductive film forming process by electroless plating. here,
Copper is easy to handle as a base metal for various platings, but has a high melting point and cannot be used as a fuse element. Therefore, on the re-formed copper metal constituting the fuse pattern, tin is laminated by spot plating to form a fuse element 22 having a portion having a melting point lower than that of copper alone.

[0006] The fuse 20 is provided with electrodes 23, 23 that have been subjected to a conductive treatment from each end of the fuse element 22 to the back surface of the support substrate 21. Further, on the surface of the support substrate 21, so as to cover the fuse element 22,
A protective layer 24 is provided.

[0007]

However, in the method disclosed in Japanese Patent Application Laid-Open No. Hei 9-510824 as shown in FIG. 5, when the fuse element 22 is formed, the fuse element 22 adheres to the support substrate 21. Since the re-forming is performed by the etching process and the conductive film generation process in order to increase the productivity, the manufacturing process is complicated and the productivity cannot be improved. Further, since the electroconductive plating is expensive and the management is complicated by electroless plating, the manufacturing cost cannot be reduced and the productivity cannot be improved, and the fuse element 22 to be re-formed with the epoxy resin plate or the polyimide resin plate cannot be improved. Adhesion is not enough.

Further, since the fuse element 22 is formed by electroless plating, the thickness tends to vary, making it difficult to obtain a predetermined element resistance value. In addition to this, in electroless plating, there are restrictions on the types of metals to be plated, and there are restrictions on the formation of the fuse element 22 having a predetermined element resistance value.

[0009] Since the metal foil is once peeled off by etching, the treatment and management of the waste liquid become complicated, and the work of collecting the peeled metal becomes complicated, resulting in an increase in cost.

Further, since the epoxy resin plate or the polyimide resin plate for the printed circuit board is reinforced with glass fiber or the like, a difference occurs in heat conduction, so that the fuse element 22 is hardened.
However, there is a problem that there is a tendency for rapid cutting due to the fusing characteristics of the.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuse and a method for manufacturing the fuse, in which the tendency of rapid cutting is avoided and the adhesion and manufacturability of the fuse element are improved.

[0012]

According to a first aspect of the present invention, there is provided a fuse comprising an insulating substrate, a polyimide resin layer provided on an upper surface of the insulating substrate, and a fuse pattern formed on the upper surface of the polyimide resin layer. And a pair of electrodes electrically connected to the fuse element and provided over the back surface of the insulating substrate.

A polyimide resin layer is provided on the upper surface of the insulating substrate, and a pair of electrodes provided over the back surface of the insulating substrate are electrically connected to the upper surface of the polyimide resin layer to form a predetermined fuse pattern. Since the element is provided, the polyimide resin layer suppresses the heat at the time of blowing the fuse element from being dissipated through the insulating substrate. For example, a ceramic material such as glass fiber having excellent strength and workability is mixed. By using an insulating substrate, heat dissipation can be suppressed to prevent the tendency to be rapidly broken by suppressing heat dissipation.For example, by forming a metal film having good adhesion to a polyimide resin layer and laminating a fuse element material on this metal film, Fuse element with high adhesion can be easily used without the need for conventional etching and conductive film reforming Made is, manufacturability is improved.

According to a second aspect of the present invention, there is provided the fuse according to the first aspect, wherein the fuse element comprises a first metal film provided in a fuse pattern on the upper surface of the polyimide resin layer; A second metal film laminated with a fuse element material.

A fuse element is formed by laminating a second metal film with a fuse element material on a first metal film provided with a predetermined fuse pattern on the upper surface of the polyimide resin layer. A fuse element having high adhesion is easily formed.

According to a third aspect of the present invention, there is provided the fuse according to the second aspect, wherein the second metal film is formed of a low melting point metal at substantially the center between the pair of electrodes of the first metal film. It is.

Further, since the second metal film is formed of a low melting point metal at substantially the center between the pair of electrodes of the first metal film, the first metal film is surely formed substantially at the center between the pair of electrodes. And stable characteristics are obtained.

According to a fourth aspect of the present invention, in the fuse according to the second or third aspect, the first metal film is made of copper;
The second metal film is made of tin, lead, antimony, aluminum,
It is a low melting point metal selected from zinc, bismuth, an alloy composed of at least two of these metals, a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy.

Then, tin, lead, antimony, aluminum, zinc, bismuth, an alloy composed of at least two kinds of these metals, tin-
Since the second metal film of a low melting point metal selected from a copper alloy, a tin-silver alloy, and a copper-silver alloy is formed by lamination, the first metal which has high adhesion to the polyimide resin layer and is easy to handle as a base Low melting point metal selected from tin, lead, antimony, aluminum, zinc, bismuth, alloys composed of at least two of these metals, tin-copper alloy, tin-silver alloy, copper-silver alloy with respect to copper in the film Is stably laminated, the second metal film of the fuse element material is formed stably with a predetermined fuse pattern, and stable characteristics are obtained.

According to a fifth aspect of the present invention, in the fuse according to any one of the second to fourth aspects, the first metal film has a thickness of 6 μm or less.

The thickness of the first metal film is set to 6 μm
For the following reason, the first metal film is formed as a thin film having a function as a base and not affecting the fusing characteristics of the fuse element, thereby achieving miniaturization.

A fuse according to claim 6 is the fuse according to any one of claims 1 to 5, wherein the insulating substrate is
The prepreg material is formed by being cured when the polyimide resin layer is formed by thermocompression bonding. The polyimide resin layer is formed by thermocompression bonding a polyimide film to the prepreg material.

Then, the polyimide film is thermocompression-bonded to the prepreg material, so that the prepreg material portion becomes the insulating substrate and the polyimide film portion becomes the polyimide resin layer, so that high adhesion between the insulating substrate and the polyimide resin layer can be obtained.

A fuse according to a seventh aspect is the fuse according to any one of the first to sixth aspects, further comprising a protective layer covering the fuse element.

Since the protective layer is provided to cover the fuse element, the fuse element is protected from external force such as impact or collision, and stable characteristics can be obtained.
Prevents metal vapor generated during fusing from adversely affecting the surroundings.

The fuse according to claim 8 is the fuse according to claim 7, wherein the protective layer is a silicone resin.

Since the soft silicone resin is used as the protective layer, the fuse element is surely prevented from being damaged by an external impact, and the arc generated when the fuse element is blown is prevented from being released to the outside. Then, the gap between the pair of electrodes is opened stably and reliably by fusing the metal film, and stable characteristics are obtained.

According to a ninth aspect of the present invention, in the method for manufacturing a fuse, a polyimide film having a first metal film provided on one surface is thermocompression-bonded on an insulating substrate with the first metal film facing upward.
The first metal film is etched into a predetermined fuse pattern, and a second fuse film is formed on the upper surface of the etched first metal film.
Is formed by plating.

Then, a polyimide film is thermocompression-bonded on an insulating substrate with the first metal film provided on one surface facing upward, and the first metal film is etched into a predetermined fuse pattern. Since the fuse element is formed by plating the second metal film on the upper surface of the metal film, the heat when the fuse element is blown is dissipated even when an insulating substrate is used by a polyimide film provided by thermocompression bonding. In addition to avoiding the tendency of rapid disconnection by suppression, a fuse that can provide a fuse element with high adhesion can be easily formed without the necessity of performing a conventional etching process and a conductive film re-forming process, thereby improving manufacturability.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a fuse, comprising:
In the method of manufacturing a fuse according to the ninth aspect, the second metal film is formed of a low melting point metal at a substantially central portion between the pair of electrodes of the first metal film.

Since the second metal film is formed of a low melting point metal at substantially the center between the pair of electrodes of the first metal film, the first metal film is surely formed substantially at the center between the pair of electrodes. And a fuse having stable characteristics can be obtained.

[0032] A method of manufacturing a fuse according to claim 11 is as follows.
The method for manufacturing a fuse according to claim 9, wherein the first metal film is made of copper, and the second metal film is made of tin, lead,
Antimony, aluminum, zinc, bismuth, alloys of at least two of these metals, tin-copper alloys, tin-
It is a low melting point metal selected from a silver alloy and a copper-silver alloy.

Then, tin, lead, antimony, aluminum, zinc, bismuth, an alloy comprising at least two of these metals, tin-
Since the second metal film of a low melting point metal selected from a copper alloy, a tin-silver alloy, and a copper-silver alloy is formed by lamination, the first metal which has high adhesion to the polyimide resin layer and is easy to handle as a base Low melting point metal selected from tin, lead, antimony, aluminum, zinc, bismuth, alloys composed of at least two of these metals, tin-copper alloy, tin-silver alloy, copper-silver alloy with respect to copper in the film Is stably laminated, the second metal film of the fuse element material is formed stably with a predetermined fuse pattern, and stable characteristics are obtained.

[0034]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fuse according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a fuse. The fuse 1 has a glass cloth resin substrate 2 as a substantially rectangular plate-like insulating substrate containing glass cloth and a thermosetting resin. The insulating substrate is not limited to the glass cloth resin substrate 2 and may be, for example, a substrate formed of a ceramic material such as alumina or glass, a substrate formed of a synthetic resin, or a composite material of a ceramic material and a synthetic resin. Any insulating material such as a substrate that has been made can be used.

The glass cloth resin substrate 2 is, for example, a glass cloth impregnated with a resin obtained by modifying epoxy resin, polyimide resin, fluorine resin, or polyphenylene ether to have a thermosetting property. Commercially available prepregs can be used. In particular, those using a polyimide resin and a polyphenylene ether resin are preferable because they have high heat-resistant properties.

On the upper surface of the glass cloth resin substrate 2, a polyimide resin layer 3 is formed as a thin film. The polyimide resin layer 3 is formed, for example, by thermocompression bonding a polyimide film 3a to the glass cloth resin substrate 2. That is, since the glass cloth resin substrate 2 has a prepreg structure in which a thermosetting resin is impregnated into a glass cloth, even a large glass cloth resin substrate 2 having a vertical dimension of 1 m and a horizontal dimension of 1 m can be easily thermocompressed by hot pressing. And bonded together.

Further, on the upper surface of the polyimide resin layer 3,
A first metal film 5 is formed along a longitudinal direction of the glass cloth resin substrate 2 in a predetermined fuse pattern, for example, in a band shape in which an intermediate portion, which is a part, becomes a narrow portion 4. The first metal film 5 has a required minimum thickness dimension of 6 μm or less, particularly 1 μm or less, which has a function as a base material and does not affect fuse characteristics by sputtering of copper, for example. Are formed in a 0.25 μm thin film. And the narrow part 4 which becomes a fuse pattern
Is formed by, for example, photoetching. In addition,
The first metal film 5 may be formed by metal deposition, bonding with an adhesive, electroless plating, or the like. In the case of bonding using an adhesive, any of an organic type and an inorganic type may be used, but a silicone resin type adhesive is particularly preferable. That is, due to the high heat resistance of the silicone resin,
Even if the narrow portion 4 generates heat when energizing or interrupting current, the transfer of heat to the polyimide resin layer 3 can be suppressed.
Can be prevented from being thermally degraded.

Further, on the upper surface of the first metal film 5, a second metal film 6 is formed by lamination. The second metal film 6 is made of, for example, tin, lead, antimony, aluminum, zinc, bismuth, or an alloy composed of at least two of these metals, or a tin-copper alloy, a tin-silver alloy, or a copper-silver alloy Is formed by plating or the like with a low melting point metal to be a fuse element material selected from the group consisting of: The first metal film 5 and the second metal film 6 constitute a fuse element 7.

The first metal film 5 is formed of copper,
When tin is used for forming the second metal film 6, alloying may occur due to the interdiffusion between copper and tin. In this case, the first metal film 5 and the second metal film 6 In between, the third metal film 8 may be formed by lamination. The third metal film 8 does not alloy with the first metal film 5 and the second metal film 6 due to the interdiffusion action, but is made of nickel or the like that prevents alloying due to the interdiffusion action between copper and tin. The metal has a required minimum thickness of 1 μm or less, for example, 0.2 μm, which has a function as a base material and does not affect fuse characteristics.
It is formed into a thin film of 5 μm by plating or the like. Note that the third metal film 8 is formed of the first metal film 5 and the second metal film 5.
When a material that does not cause alloying due to the interdiffusion with the metal film 6 is used, it is not provided in terms of manufacturability and cost.

On the back surface of the glass cloth resin substrate 2, a pair of strip-shaped electrolytic copper foils 9 are provided in the width direction at both ends in the longitudinal direction. The electrolytic copper foil 9 is, for example, a thin film sheet-shaped copper electrolytic foil 9a adhered by thermocompression bonding, and then an intermediate portion is removed by an etching process so as to be spaced apart at both longitudinal ends of the glass cloth resin substrate 2. And a pair is formed. Since the glass cloth resin substrate 2 has a prepreg structure in which a glass cloth is impregnated with a thermosetting resin, the electrolytic copper foil 9 has a length of 1 m and a width of 1 m. And easily bonded by thermocompression bonding.

Further, at both ends in the longitudinal direction of the glass cloth resin substrate 2, both ends of the second metal film 6, that is, wide ends where the narrow portion 4 serving as a fuse pattern is not located, are separated from the glass cloth resin substrate 2. A plating layer 10 having a substantially U-shaped cross section is formed by, for example, electroless plating over the electrolytic copper foil 9 on the end face and the back face in the longitudinal direction. The electrode 11 is composed of the electrolytic copper foil 9 and the plating layer 10. The plating layer 10 may be formed by forming a conductive paste into a layer by printing, dipping, or the like, and curing the layer. Further, the surface of the plating layer 10 may be subjected to solder plating.

Further, an insulating protective layer 13 is provided between the electrodes 11 on the surface side of the glass cloth resin substrate 2 so as to cover the fuse element 7. This protective layer 13
Is formed of a thermosetting resin such as an epoxy resin, a polyimide resin, or a silicone resin by screen printing or etching.

As the protective layer 13, for example, a silicone resin layer is provided on the upper surface of the glass cloth resin substrate 2, and an epoxy resin layer serving as a second protective layer which is a thermosetting resin is formed on the upper surface of the silicone resin layer. A structure formed by laminating a plurality of layers, such as a two-layer structure described above, may be used. By providing an epoxy resin on the outer layer side and a silicone resin on the inner layer side, a soft silicone resin having a relatively low adhesive strength absorbs an external impact and an impact at the time of fusing the narrow portion 4 serving as the fuse element 7. To prevent damage to the narrow portion 4 and protect the silicone resin with a high-strength epoxy resin to prevent damage due to the impact of the silicone resin. By covering the narrow portion 4, deterioration of the narrow portion 4 can be prevented for a long period of time.

In the two-layer structure, the first protective layer is not limited to the silicone resin, but may be made of any other soft synthetic resin which is excellent in heat resistance, has a very low adhesive strength to the fuse element 7 and is not soft. Synthetic resin may be used. further,
The second protective layer is not limited to an epoxy resin, and may be any other synthetic resin having high mechanical strength and impermeable to gas or moisture.

Next, a process for manufacturing the chip-shaped fuse 1 will be described.

First, as shown in FIG. 3, a substantially rectangular flat glass cloth resin plate 15 formed by impregnating a glass cloth with a thermosetting resin in advance, for example,
A polyimide film 3a provided with a sputtered film 16 in which a thin film is formed in advance by, for example, copper sputtering is placed on the upper side of the glass cloth resin plate 15 on the side opposite to the glass cloth resin plate 15 and overlapped. A copper electrolytic foil 17 is overlaid on the other surface of the plate 15. Then, they are hot-pressed in the state of being laminated, and are thermocompression-bonded to each other.

Next, the sputtered film 16 is subjected to a chemical etching process so as to have a predetermined fuse pattern, and the first
Is formed. Further, the electrolytic foil 17 located on the back side is similarly subjected to a chemical etching process to form an electrolytic copper foil 9 having a band shape facing at a predetermined interval, that is, a plurality of slit-like patterns.

Thereafter, a low-melting point metal such as tin is laminated on the upper surface of the first metal film 5 by, for example, electroplating, and a second metal film 6 is formed. The fuse element 7 is configured.

When, for example, the first metal film 6 is formed of copper and the second metal film 6 is formed of tin, alloying may occur due to the interdiffusion between copper and tin. By such an interdiffusion effect, the first metal film 5 and the second metal film 6
When there is a risk that the second metal film 6
Before the formation of the third metal film 5, the upper surface of the first metal film 5 is plated with a metal such as nickel, which does not exhibit an interdiffusion effect.
Is formed, and a second metal film 8 is formed on the upper surface of the third metal film 8.
Is formed.

Further, a belt-like shape, for example, a silicone resin having a thickness of 40 μm, which is located on the surface side of the glass cloth resin plate 15 and covers the narrow portion 4 of the fuse element 7 in a belt-like shape.
After screen printing, a protective layer 13 is formed by exposing to an atmosphere of about 120 ° C. for 2 hours and heat-curing.

Next, the strip-shaped electrolytic copper foil 9 is cut along the longitudinal direction at the center position in the width direction to cut out a strip-shaped strip. The glass cloth resin plate 15 can be easily cut because it is not brittle like ceramics and glass. Then, the cut surface of the strip obtained by this cutting, the both ends of the second metal film 6 on the front surface side, and the electrolytic copper foil 9 on the rear surface side are cut from the surface by, for example, a combination of electroless plating and electrolytic plating. An electrode is formed with the electrolytic copper foil 9 by forming a plating layer 10 having a substantially U-shaped cross section over the surface and the back surface. That is, electroless copper plating is applied to the exposed end portions, which are the end portions not covered with the protective layer 13 of the strip, and the electrolytic copper foil 9. Alternatively, the cut surface of the strip is dipped on a surface coated with, for example, a conductive paste, and the cut surface and the exposed second electrode films 6 and 6 and the electrolytic copper foil 9 are applied and printed. Exposure for 30 minutes and heat curing may form the plating layer 10 having a substantially U-shaped cross section.

Thereafter, the strip is placed at the center between the narrow portions 4 of the fuse element 7 in the width direction, for example, the length is approximately 2 mm, the width is approximately 1.25 mm, and the thickness is approximately 0.5.
Cut into mm-shaped chips. Then, for example, characters or symbols such as electric characteristics are marked on the upper surface of the protective layer 13 to obtain the surface-mounted fuse 1.

As described above, the polyimide film 3a provided with the sputtered film 16 serving as the first metal film 5 with the necessary minimum thickness dimension which does not affect the fuse characteristics is thermocompression-bonded to the glass cloth resin plate 15. Since the second metal film 6 is formed by laminating a low melting point metal of the fuse element material with the first metal film 5 as a base, the fuse element 7 and the glass cloth resin are formed as in the related art. After the copper foil provided on the glass cloth resin substrate 2 is entirely etched to improve the adhesion to the substrate 2, tin is laminated and formed in a later step by a conductive film generation process by electroless plating. This eliminates the need for a step of re-forming copper with a predetermined fuse pattern, thereby improving the manufacturability and reducing the heat generated when the fuse element 7 is blown off by the glass cloth. Since the radiation through the resin substrate 2 can be suppressed, for example, even if a glass cloth resin plate 15 mixed with a ceramic material such as glass fiber having excellent strength and workability is used, the tendency to quickly break due to the suppression of heat radiation is reduced. Can be avoided.

Since the fuse element 7 is formed by electrolytic plating on the metal film etched on the predetermined fuse pattern of the polyimide film 3a, variation in plating thickness is less likely to occur, and variation in element resistance is reduced. Fusing time can be easily obtained, stable characteristics can be obtained, and the electroplating that can be continuously processed with few restrictions on metal types can expand the range of element resistance values to be set. Fuse 1 can be easily formed, and the productivity can be improved.

Further, since the etching is performed to the predetermined fuse pattern, the amount of the metal to be peeled is reduced, the treatment and management of the waste liquid are facilitated, and the manufacturing cost can be reduced.

The first metal film 5 formed of copper
And tin, lead, antimony, aluminum, zinc, bismuth, alloys of at least two of these metals, tin-
Since the second metal film 6 of a low-melting metal selected from a copper alloy, a tin-silver alloy, and a copper-silver alloy is formed by lamination, the first metal film has high adhesion to the polyimide resin layer 3 and is easy to handle as a base.
Is selected from tin, lead, antimony, aluminum, zinc, bismuth, alloys composed of at least two of these metals, tin-copper alloy, tin-silver alloy, and copper-silver alloy The second metal film 6 of the low melting point metal can be stably laminated, and the second metal film of the fuse element material can be reliably and stably formed with a predetermined fuse pattern, so that stable characteristics can be obtained.

Then, the first metal film 5 formed of copper
To form a third metal film 8 made of nickel between the first metal film 5 and the second metal film 6 made of tin. Prevents alloying of tin and tin by interdiffusion, preventing a decrease in adhesion.
Fuse 1 having stable characteristics can be obtained.

Further, the thickness of the first metal film 5 is set to 6 μm.
Since it is set to m or less, it can be formed into a thin film which has a function as a base and does not affect the fusing characteristics of the fuse element, and can be reduced in size.

Further, since the first metal film 5 is provided on the upper surface of the polyimide resin layer 3 by sputtering, the first metal film 5 has a function as a base for various platings and has a function as a fuse element 7.
Can be easily formed into a thin film that does not affect the fusing characteristics of the polyimide resin layer 3 by sputtering.
Since fine irregularities are formed on the surface of the first metal film 5 and the first metal film 5 is formed on the irregularities, the adhesion of the first metal film 5 can be improved, and stable characteristics can be easily obtained. Also, manufacturability can be improved.

Then, a polyimide film 3a is thermocompression-bonded to a glass cloth resin plate 10 which is an unheat-cured glass cloth resin substrate 2 having a prepreg structure, and the polyimide resin layer 3 is integrally formed on the cured glass cloth resin substrate 2. Since the polyimide resin layer 3 is formed, high adhesion of the polyimide resin layer 3 is obtained, and the polyimide resin layer 3 can be easily formed only by hot pressing, so that the productivity can be improved.

Further, since the protective layer 13 is provided, the fuse element 7 can be protected from an external force such as an impact or a collision, so that stable characteristics can be obtained and the surroundings are adversely affected by metal vapor generated at the time of fusing. Can be prevented.

Furthermore, since the protective film 13 is formed of a thermosetting resin, the fuse element 7 can be covered and fixed, and damage to the fuse element 7 due to external stress can be prevented.

Further, since the protective film 13 is formed by using a silicone resin as a thermosetting resin, damage to the fuse element 7 due to an external impact can be prevented, and an arc generated when the fuse element 7 is blown can be prevented. It can be prevented from being released to the outside, and the gap between the pair of electrodes 11, 11 due to the fusing of the fuse element 7 can be stably and reliably opened.
Stable characteristics can be obtained.

On the other hand, since the electrodes 11, 11 are provided in a substantially U-shaped cross section over the back surface of the glass cloth resin substrate 2 opposite to the side on which the fuse element 7 is provided, the electrodes 11, 11 are provided.
The bonding strength with the glass cloth resin substrate 2 can be increased, the bonding property can be improved, and damage such as peeling of the electrodes 11, 11 can be prevented.

On the other hand, since the high-strength glass cloth resin substrate 2 which is inexpensive and easily available and contains glass cloth and thermosetting resin is used, processing such as cutting at high speed is easy, and productivity can be improved. Since the thermal conductivity is low, it is possible to prevent the characteristics from fluctuating due to the ambient temperature and to prevent the fuse element 7 from falling off from the mounting portion of the circuit board due to heat generated by the narrow portion 4 constituting the fuse element 7. Damage such as carbonization of the glass cloth resin substrate 2 due to heat generated at the time of current interruption can be prevented, variation in fusing characteristics, reduction in breaking performance, and reduction in insulation resistance after fusing can be prevented, and reliability can be improved.

In the above embodiment, a plurality of narrow portions 4 may be provided in one fuse 1 as needed.

Further, although the description has been made using copper as the first metal film 5, any metal which has a function as a base and does not affect the fuse characteristics may be used. In addition, easy-to-handle copper is preferable as a base metal for various platings.

The second metal film 6 may be formed of any low melting point metal, particularly, tin, lead, antimony, aluminum, zinc, bismuth, an alloy comprising at least two of these metals, Tin-copper alloy, tin-silver alloy,
A low melting point metal selected from a copper-silver alloy is preferred.

The second metal film 6 may be provided substantially only at the center of the first metal film 5 in the longitudinal direction, that is, substantially at the center between a pair of electrodes provided at both ends. According to this configuration, the first metal film 5 can be reliably blown at a substantially intermediate position and stable characteristics can be obtained, and the area where the second metal film 6 is provided is reduced, and the amount of material is reduced. Also, the cost can be reduced.

[0071]

EXAMPLE The fuse 1 formed according to the above-described embodiment was observed for its fusing condition by a fusing test.

Note that a sample manufactured in the same manner as in the above embodiment was used.

That is, the glass cloth resin plate 15 is a glass cloth resin plate (Toshiba Chemical Co., Ltd.) which is a prepreg having a thickness of 0.4 mm in which a glass cloth is impregnated with a thermosetting polyphenylene ether resin. Product name: TLP-596-DA), and the polyimide film 3a provided with the sputtered film 16 is a sputtered film.
16 thickness dimension is about 0.25μm, thickness dimension is about 50μm
(Trade name: Etcherflex EAF-SANU2 (025), manufactured by Mitsui Chemicals, Inc.), electrolytic copper foil
17 has a thickness of about 18 μm (JIS-C-6513
And a fuse pattern was formed by etching. Further, as the second metal film 6, tin was formed to a thickness of about 20 μm by electroplating. Further, the third metal film 8 was formed to a thickness of about 0.5 μm by nickel plating. Furthermore, the protective layer 13
Was formed by screen printing using a silicone resin (trade name: KE1831 manufactured by Shin-Etsu Chemical Co., Ltd.) and thermosetting. Then, a fuse 1 serving as a sample having a vertical dimension of about 1.25 mm and a horizontal dimension of about 2 mm was cut out.

As a comparative sample, copper on a copper-clad printed wiring board (FCL-GI 18-18 specified in JIS-C-6490, thickness 0.4 mm) was completely peeled off by etching.
Copper plating is electrolessly plated on one surface of the printed wiring board with a similar fuse pattern to form a first metal film 5 on the one surface of the printed wiring board, and the upper surface of the first metal film 5 formed by this plating is formed on the first metal film 5. Similarly, a third metal film 8 was formed by nickel plating and a second metal film 6 was formed by electroplating tin, and an electrode 11 and a protective layer 13 were provided respectively.

Then, as a result of performing a fusing test on each sample surface-mounted on a standard test board by reflow soldering, as shown in FIG. However, in the case of the above-mentioned embodiment, the time until the melting was long, and the rapid cutting was prevented.

Further, in the case of the comparative sample, the printed wiring board corresponding to the glass cloth resin substrate was burned by the heat at the time of blowing the fuse element, but in the case of the embodiment, the glass cloth resin substrate 2 did not burn. .

Further, in the case of the example, peeling of the polyimide film 3a was not recognized.

Next, an experiment was conducted on the relationship between the thickness of the first metal film 5 and the fusing.

The sample was a polyimide film
A copper film electroplated to a thickness of 5 μm on a sputtered film 16 having a thickness of 3a of about 0.25 μm, and
Using a copper film electrolytically plated so as to have a thickness of 7 μm,
Fuse 1 manufactured in the same manner as in the above example was used.

As a result of the same fusing test, when the copper film was formed to a thickness of 5 μm, the time until fusing was longer than that in the comparative example, as in the above-mentioned example, and the rapid cutting was prevented. Further, the glass cloth resin substrate 2 did not burn. On the other hand, when the copper film was formed in a thickness of 7 μm, the glass cloth resin substrate 2 was burned before the fusing. Therefore, it is understood that the thickness of the copper film as the first metal film is preferably set to 6 μm or less.

Further, an experiment was conducted on the fusing property of the third metal film 8.

As a sample, a lead-tin alloy (90% lead, 90% lead) was used as the second metal film 6 without providing the third metal film 8.
Tin (10%) was formed in the same manner as in the above example, except that the thickness was about 20 μm by electroplating.

Then, as a result of performing a fusing test in the same manner as in the above example, the time until fusing was longer than that of the comparative example, so that rapid cutting could be prevented. Further, the glass cloth resin substrate 2 did not burn.

[0084]

According to the fuse of the present invention, a polyimide resin layer is provided on the upper surface of the insulating substrate, and a fuse element constituting a predetermined fuse pattern is provided on the upper surface of the polyimide resin layer. This prevents the heat generated when the fuse element is blown from being radiated through the insulating substrate.For example, even when using an insulating substrate mixed with a ceramic material such as glass fiber, which has excellent strength and workability, the heat dissipation can be suppressed. In addition to avoiding the tendency of rapid cutting, for example, by forming a metal film with good adhesion on a polyimide resin layer and laminating a fuse element material on this metal film, a fuse element with high adhesion can be etched by conventional etching. It can be easily formed without performing the processing and the conductive film reforming processing, and the productivity can be improved.

According to the fuse of the second aspect, in addition to the effect of the fuse of the first aspect, a fuse element material is formed on the first metal film provided in a predetermined fuse pattern on the upper surface of the polyimide resin layer. Since the fuse element is formed by laminating the second metal film, a fuse element having high adhesion can be easily formed.

According to the fuse of the third aspect, in addition to the effect of the fuse of the second aspect, the second metal film is formed of a low melting point metal at substantially the center of the first metal film. The one metal film can be reliably blown at substantially the center, and stable characteristics can be obtained.

According to the fuse of the fourth aspect, in addition to the effect of the fuse of the second or third aspect, tin, lead, antimony, aluminum, zinc, bismuth, or the like of the metal is formed on the first metal film of copper. An alloy of at least two types,
Since the second metal film of a low melting point metal selected from a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy is formed by lamination, the first metal film having high adhesion to the polyimide resin layer and easy to handle as a base is provided.
With respect to copper of the metal film, tin, lead, antimony, aluminum, zinc, bismuth, an alloy composed of at least two of these metals, a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy. The second metal film of the melting point metal can be stably laminated, and the second metal film of the fuse element material can be reliably and stably formed with a predetermined fuse pattern, so that stable characteristics can be obtained.

According to the fuse of the fifth aspect, in addition to the effect of the fuse of the second aspect, the thickness of the first metal film is set to 6 μm or less. Can be formed into a thin film having a function as a base and not affecting the fusing characteristics of the fuse element, and can be reduced in size.

According to the fuse of the sixth aspect, in addition to the effect of the fuse according to any one of the first to fifth aspects, a polyimide film is thermocompression-bonded to the prepreg material, so that the prepreg material portion becomes an insulating substrate and the polyimide film is formed. Since the portion becomes the polyimide resin layer, high adhesion between the insulating substrate and the polyimide resin layer is obtained, and stable quality is obtained.

According to the fuse according to the seventh aspect, in addition to the effect of the fuse according to any one of the first to sixth aspects, since a protective layer covering the fuse element is provided, the fuse element is protected from external force such as impact or collision. As a result, stable characteristics can be obtained, and adverse effects on the surroundings due to metal vapor generated at the time of fusing can be prevented.

According to the fuse of the eighth aspect, in addition to the effect of the fuse of the seventh aspect, since a soft silicone resin is used as the protective layer, damage to the fuse element due to external impact can be reliably prevented. ,
The arc generated when the fuse element is blown can be prevented from being released to the outside, and the pair of electrodes can be stably and reliably opened by blowing the metal film, so that stable characteristics can be obtained.

According to the fuse manufacturing method of the ninth aspect, the polyimide film is thermocompression-bonded on the insulating substrate with the first metal film on one side facing upward, and the first metal film is formed into a predetermined fuse pattern. After the etching process, the second metal film is formed by plating on the upper surface of the first metal film to form a fuse element. Even when using a fuse, it is possible to avoid the tendency of rapid disconnection due to the effect of suppressing heat dissipation, and to easily form a fuse capable of obtaining a fuse element with high adhesion without performing the conventional etching process and conductive film reforming process. Performance can be improved.

According to the method for manufacturing a fuse according to the tenth aspect, in addition to the effect of the method for manufacturing a fuse according to the ninth aspect, the second metal film is formed of a low melting point metal at substantially the center of the first metal film. Since the first metal film is formed by lamination, the first metal film can be reliably blown at substantially the center, and a fuse having stable characteristics can be obtained.

According to the method of manufacturing a fuse according to the eleventh aspect, in addition to the effect of the method of manufacturing a fuse according to the ninth or tenth aspect, tin, lead, antimony, aluminum, zinc is formed on the first metal film of copper. , Bismuth, alloys of at least two of these metals, tin-copper alloys, tin-silver alloys,
Since a second metal film of a low melting point metal selected from a copper-silver alloy is formed by lamination, adhesion to the polyimide resin layer is high and copper of the first metal film which is easy to handle as a base is formed.
Tin, lead, antimony, aluminum, zinc, bismuth,
A second metal film of a low-melting-point metal selected from at least two of these metals, a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy can be stably laminated, and the second metal film of the fuse element material can be formed. The second metal film can be formed stably with a predetermined fuse pattern, and a fuse having stable characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a fuse according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is an explanatory view illustrating a thermocompression bonding step in the manufacture of the fuse.

FIG. 4 is a graph illustrating a state of blowing the fuse.

FIG. 5 is a sectional view showing a conventional fuse.

[Explanation of symbols]

 Reference Signs List 1 fuse 2 glass cloth resin substrate 3 polyimide resin layer 3a polyimide film 5 first metal film 6 second metal film 7 fuse element 8 third metal film 11 electrode 13 protective layer

Claims (11)

[Claims] An insulating substrate; a polyimide resin layer provided on an upper surface of the insulating substrate; a fuse element provided on the upper surface of the polyimide resin layer by forming a fuse pattern; And a pair of electrodes connected over the back surface of the insulating substrate. 2. A fuse element comprising: a first fuse element formed on a top surface of a polyimide resin layer by forming a fuse pattern;
2. The fuse according to claim 1, further comprising: a metal film formed by: a second metal film laminated on the metal film with a fuse element material. 3. The fuse according to claim 2, wherein the second metal film is formed of a low-melting-point metal at substantially the center between the pair of electrodes of the first metal film. 4. The first metal film is made of copper, and the second metal film is made of tin, lead, antimony, aluminum,
4. The fuse according to claim 2, wherein the fuse is a low melting point metal selected from zinc, bismuth, an alloy of at least two of these metals, a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy. . 5. The fuse according to claim 2, wherein the first metal film has a thickness of 6 μm or less. 6. The insulating substrate is formed by curing a prepreg material during the formation of a polyimide resin layer by thermocompression bonding. The polyimide resin layer is formed by thermocompression bonding of a polyimide film to the prepreg material. The fuse according to any one of claims 1 to 5, characterized in that: 7. The fuse according to claim 1, further comprising a protective layer covering the fuse element. 8. The fuse according to claim 7, wherein the protective layer is a silicone resin. 9. A polyimide film having a first metal film provided on one surface is thermocompression-bonded on an insulating substrate with the first metal film facing upward, and the first metal film is formed into a predetermined fuse pattern. Etching, and forming a second metal film by plating on the upper surface of the etched first metal film. 10. The second metal film is made of a low-melting metal and is made of a first metal.
10. The method of manufacturing a fuse according to claim 9, wherein the metal film is formed by lamination substantially at the center between the pair of electrodes. 11. The first metal film is made of copper, and the second metal film is made of tin, lead, antimony, aluminum,
11. The fuse according to claim 9, wherein the fuse is a low melting point metal selected from zinc, bismuth, an alloy of at least two of these metals, a tin-copper alloy, a tin-silver alloy, and a copper-silver alloy. Manufacturing method.