JPH0449735B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an overload fusing type resistor, and an object thereof is to provide a resistor that quickly fuses due to self-heating of the resistive film itself when an overcurrent flows. Recently, there has been a trend toward smaller devices and lower power consumption, and with this trend, overload fusing type resistors are
It is required to interrupt the current even if the applied power during abnormality is a low multiplier with respect to the rated power. Additionally, in the low resistance region, there is an increasing demand for substitutes for current fuses. Conventionally, this type of overload fusing type resistor is made by applying a low melting point glass paste onto a general resistance film such as a metal film, metal oxide film or carbon film. It takes advantage of the difference in coefficient of thermal expansion between the resistive film and the material that supports or protects it. A device that partially narrows the current path, causing heat concentration and melting. Some use a fusing type resistance film. However, with these conventional devices, it is difficult to fuse at a low magnification of 4 to 5 times the rated power. The manufacturing method of the present invention is one based on the above-mentioned concept, in which the surface of the insulating substrate is subjected to pre-treatments such as degreasing and cleaning, and an activation treatment is performed to form a Sn layer or an Ag layer.
After forming the layer on the surface of the insulating substrate, the electrical resistance value of the Ag layer, Sn layer, or a mixture layer or laminate layer thereof is determined by a silver mirror method or an electroless plating method, regardless of the metal. is 0.1~15
Deposit to a thickness of 1 μm or less in the Ω range,
Next, acid treatment is performed using sulfuric acid or hydrofluoric acid, and the substrate coated with the metal film is used as a cathode.
The feature is that the Sn layer, Pb layer, or Sn-Pb alloy film layer is precipitated and formed by electrolytic plating to form a resistive film, and it cuts off current stably and accurately at a low power multiplier, and when operating at rated operation, it is a general resistance film. It provides products with the same performance and reliability as conventional equipment at a lower price. Hereinafter, specific embodiments of the present invention will be described in FIGS. 1 to 5.
This will be explained based on the diagram. Figure 1 shows the solder layer (Sn-
Figures 2a and 2b are diagrams showing the manufacturing process in the case where a Pb alloy layer (Pb alloy layer) is formed, and the manufacturing process is shown in cross-sectional views of the resistive film. First, in Fig. 2a, 1 is an insulating substrate made of porcelain that has been degreased and cleaned.This is, for example, a cylindrical porcelain with a diameter of 1.7 mm and a length of 5.5 mm that has been degreased with hot alkaline solution, washed, and cleaned. That's what I did. Reference numeral 2 denotes an activation treatment layer consisting of a Sn layer or an Ag layer formed on the surface of the insulating substrate 1 by wet activation treatment. It is formed by imparting sensitivity and activating it. In addition, instead of the above wet activation treatment, a vapor deposition method,
It is also possible to form the Sn layer or Ag layer by activation treatment using a dry method such as a sputtering method. 3 is an Ag layer or a Sn layer as a base metal layer deposited on the activation treatment layer 2, and is formed by a silver mirror method or an electroless plating method. Note that this Ag layer or Sn layer 3 may be a mixture or a laminate thereof. The following points can be mentioned as conditions for such a base metal. <Condition 1> The surface of the insulating substrate 1, which is a ceramic electrical nonconductor, is given electrical conductivity so that it can be plated as a cathode during subsequent solder plating. For this purpose, an electrical resistance value of 0.1 to 15Ω is desirable. <Condition 2> The resistance value must become infinite when the solder film melts due to overheating. In other words, the initial conduction of the underlying metal film must not remain. To achieve this, the underlying metal itself must be thin (1 μm or less thick). <Condition 3> It must be easy to diffuse and mix into the solder layer, or the surfaces must be compatible with each other. In other words, the adhesion with the insulating substrate 1 should not cause any practical problems, but should be at a level that does not prevent agglomeration during melting of the solder layer. As conductive films that meet the above conditions, first of all, oxides or semiconductor films such as tin oxide and indium oxide are excluded, and even metal films such as Cu-Ni and Ni are excluded.
-P, Ni-B, etc. were found to be non-conforming as a result of the implementation confirmation. As a result of the study, the base metal film of Ag and Sn satisfies the above conditions. If the base metal film is too thick, there will be no problem with solder plating, but if it is fused, continuity will remain, and if it is too thin, the resistance will be high and it will be difficult to obtain an appropriate cathode current density at the initial stage of solder plating. Therefore, as a result of experiments, it has been found that the thickness of the base metal is in the range of 0.1 to 15 Ω in terms of resistance value, and more preferably in the range of 0.7 to 7 Ω. Next, a silver mirror method will be described as an example of a method for depositing the base metal. In this method, Ag is deposited on the insulating substrate 1 by bringing the plating solution into contact with the surface of the insulating substrate 1 that has been pretreated up to the activation treatment as described above. A method of spraying the I liquid and the liquid at the same time from separate nozzles so that the I liquid and the liquid come into mixed contact on the surface of the insulating substrate 1, or a method of spraying the I liquid and the liquid immediately before spraying. There are a method of mixing and spraying with a single nozzle, a method of immersing the insulating substrate 1 in a solution of a mixture of the I-liquid and the liquid, and the like. The plating compositions of the liquid I and the liquid shown in Table 1 below are known. In addition, depending on the target substrate, the composition may be changed slightly, other types of reducing agents may be used, or in some cases, three or four types of preservation solutions may be added in advance as shown in Tables 2 and 3 below. Some formulations include mixing.

【table】

【table】

[Table] In addition to the above-mentioned silver mirror method, other methods for attaching the base metal
There is an electroless plating method for Sn, but in this case, careful consideration must be given to liquid management in view of the stability of the plating solution, so the silver mirror deposition method described above is more advantageous. However, Sn has the same effect as Ag as a base metal film. In addition, to form a layer of a mixture of Ag and Sn as described above, it is sufficient to deposit the mixture, and furthermore, to deposit a layer of a laminate of Ag and Sn, the silver mirror method described above can be used. The electroless plating method can be performed successively in random order, and the effect is not different from the case of using Ag alone. Other methods for depositing the base metal include dry methods such as vapor phase plating, ion plating, sputtering, and vapor deposition, but these methods cannot be said to be preferable for mass production or practical purposes. It is. In addition, in FIG. 2a, 4 is a solder layer, and after forming the Ag or Sn layer 3 as the base metal layer, acid treatment with sulfuric acid or hydrofluoric acid is performed, and then the base metal layer is deposited. The solder layer 4, which is a Sn--Pb alloy film, is precipitated and formed by electroplating in a solder plating bath using the base as a cathode. Here, as a general treatment method before soldering, there is a method of dissolving the surface layer with a mixed acid such as sulfuric acid-nitric acid or sulfuric acid-hydrogen peroxide, but in the case of the present invention, an extremely thin layer of metal coating is applied to the base layer. Because of this, mixed acids that would etch the underlying film cannot be used. Therefore, sulfuric acid
100g/or hydroborofluoric acid (30-50%)
This is possible by immersing it in 30g/~200g/ of water for a short time. Pretreatment with a hydroborofluoric acid solution is more desirable. Next, as an example of solder plating, the most commonly used solder plating composition is a porcelain solder plating composition. For example, as hydroborofluoride,
Contains Sn9~52g/, Pb30~90g/, hydroborofluoric acid 100~600g/, boric acid 0~60g/
coexist, and perform electrolytic plating at a cathode current density of 1 to 5 A/cm ² . Usually, the above solder plating composition includes:
In order to obtain a film with good properties, peptone 1~
It is called a peptone bath because 10 g/g of the bath is added, but peptone can be replaced with one or more of other organic additives such as gelatin and glue.
Furthermore, it is also known to perform electrolytic plating by adding brighteners such as formalin, organic amines, aldehydes, or ketones. Although the case where the solder layer 4 is formed by electrolytic plating has been described here, it may also be formed by depositing a Sn or Pb film. Note that the activation treatment layer 2, the Ag layer or the Sn layer 3,
It has been confirmed that the following 24 combinations of metals selected for the solder layer 4 are effective. i.e. ^* (Sn, Ag, Sn), (Sn, Ag,
Pb), ^* (Sn, Ag, Sn-Pb alloy), ^* (Sn, Sn,
Sn), (Sn, Sn, Pb), ^* (Sn, Sn, Sn-Pb alloy), (Sn, Ag-Sn mixture, Sn), (Sn, Ag-Sn
Mixture, Pb), (Sn, Ag-Sn mixture, Sn-Pb alloy), (Sn, Ag-Sn laminate, Sn), (Sn, Ag-Sn
Laminate, Pb), (Sn, Ag-Sn laminate, Sn-Pb alloy), ^* (Ag, Ag, Sn), (Ag, Ag, Pb), ^* (Ag,
Ag, Sn-Pb alloy), ^* (Ag, Sn, Sn), (Ag,
Sn, Pb), ^* (Ag, Sn, Sn-Pb alloy), (Ag, Ag
-Sn mixture, Sn), (Ag, Ag-Sn mixture, Pb),
(Ag, Ag-Sn mixture, Sn-Pb alloy), (Ag, Ag
-Sn laminate, Sn), (Ag, Ag-Sn laminate, Pb),
(Ag, Ag-Sn laminate, Sn-Pb alloy),
Among these, the combinations marked with * are particularly preferred because they are practical and can be manufactured at low cost. Next, the resistive film shown in FIG. 2a formed as described above was heat-treated at 150°C to 170°C for 5 hours to form a Pb-
An alloy resistance film 5 made of Sn-Ag was obtained. Here, after forming the activation treatment layer 2 of the Sn layer or Ag layer, the Ag layer or Sn layer 3 is applied so that the solder layer 4 can be properly deposited on the final purpose of having a fusing function. By finally performing heat treatment, the activation treatment layer 2, Ag layer or Sn layer 3, and solder layer 4 are alloyed, creating an alloy consisting of Pb-Sn-Ag that can be used as a resistor. This becomes the resistive film 5. In addition, in the overload fusing type resistor of the present invention,
It is the solder layer 4 formed as the third layer that performs the fusing function, and even if it is not alloyed by the heat treatment described above, it can be used as an overload fusing type resistor. In other words, an overload fusing type resistor can be obtained by forming a laminated structure of an activation treatment layer 2, an Ag or Sn layer 3, and a solder layer 4, and a resistor having these layered structures can be heat-treated to form an alloy. An overload fusing type resistor can also be constructed by As mentioned above, the third solder layer 4 is necessary to provide the fusing function, and even when alloyed by heat treatment, not all metals are completely alloyed. An overload fusing type resistor can also be obtained even if the metal layer is partially alloyed at the boundary between the metal layers. Therefore, activation treatment layer 2, Ag layer or Sn
In the case of a laminated structure or an alloyed structure of layer 3 and solder layer 4, the combination of metals in each layer is as follows:
As mentioned above, the same effect can be obtained in terms of fusing function even if the combination of the same type of metal or the combination of different types of metal is used. In short, as the third layer, which is the metal layer that performs the fusing function, the Sn layer and Pb
layer or Sn-Pb alloy film layer, and a third layer of Sn layer, Pb layer or Sn-
The effects of the present invention can be obtained by using an Ag layer, Sn layer, a mixture layer thereof, or a laminate layer thereof, which is easily diffused and mixed into the Pb alloy film layer, has an electrical resistance value in the range of 0.1 to 15Ω, and has a thickness of 1 μm or less. The effect will be obtained. FIG. 3 further shows that on top of the alloy resistance film 5 made of Pb-Sn-Ag shown in FIG. This shows how it was done. This thermo-softening resin layer 6 is formed by cutting grooves in the Pb-Sn-Ag alloy resistance film 5 to correct the resistance value, if necessary.
It is applied with a brush-like tool to cover a part or the whole of the alloy resistance coating 5 including the grooved central part or the uncut central part, or it is formed by a dipping method or a printing method. Finally, the entire structure is covered with an insulating material such as a heat-shrinkable tube, thereby completing the production of the overload fusing type resistor. FIG. 4 shows an example of the structure of a resistor manufactured in this manner, and is of a general resistor type with lead wires. In FIG. 4, reference numeral 7 denotes a resistor in which a Pb-Sn-Ag alloy resistance film is formed on the surface of the insulating substrate 1 as described above. A groove cut portion 8 is formed. Furthermore, conductive caps 9 are press-fitted into both ends of the resistor 7, and lead wires 10 are welded to the caps 9. Furthermore, 6 is the above-mentioned thermoplastic resin layer, which is provided in a portion of the resistor 7 including the grooved central portion. 11 is an insulator such as a heat shrink tube. Next, the fusing function of the alloy resistance film 5 made of Pb-Sn-Ag of this example will be explained.
When an overcurrent flows through the alloy resistance film 5 made of Pb-Sn-Ag, which has a low melting point, during an overload, the alloy resistance film 5 generates heat, and when its temperature reaches its melting point, it begins to melt. At the same time, the viscosity of the six heat-softening resin layers shown in FIG. 3 decreases due to heat softening. Then, the molten alloy resistance film 5 becomes spherical due to surface tension, and fusion is achieved. At this time, the thermosoftening resin layer 6 whose viscosity has decreased is replaced by the alloy resistance coating 5.
It does not inhibit clumping and melting is quickly achieved. Here, we will explain the fusing function in the case of a resistive film consisting of a Sn layer, a Sn layer, and a Sn-Pb alloy layer.
In the case of a resistive film with such a laminated structure, when an overcurrent flows through the resistive film, the thin
The Sn layer generates heat and the Sn layer diffuses into the Sn--Pb alloy layer, thereby lowering the melting point of the Sn layer portion, and then the Sn--Pb alloy layer generates heat and begins to melt. At this time, the Sn layer diffuses into the Sn--Pb alloy layer and its melting point decreases as described above, so the Sn--Pb alloy layer melts and is cut. The operation after this is
The behavior is similar to that of the alloy resistance film described above.
Fusing is achieved quickly. FIG. 5 shows an example of the fusing characteristics of the resistor of the present invention. In this case, we prototyped the following overload fusing type resistor. In other words, 10,000 insulators with a diameter of 1.7 mm and a length of 5.5 mm were plated as shown below, and the resistance value was 50 mΩ.
An overload fusing type resistor was obtained. After pre-treatment to roughen the surface of the insulator, a Sn layer as the first layer and an Ag layer as the second layer are formed until the resistance value reaches 0.3 to 0.6Ω, and a Sn-Pb layer as the third layer is formed to achieve a resistance of 50mΩ. As a body. This overload fusing characteristic was tested. The test method is as follows. The test will be conducted using the circuit shown in Figure 6, and a constant voltage power source will be used as the power source. In the figure, R ₁ is a test resistor, R ₂ is a high power stabilizing resistor, and its resistance value is 30 to 50 times that of R ₁ , and R ₁ is connected in series. Here, in advance, use a high-power dummy resistor instead of the test resistor _R1 , and adjust the power supply voltage to meet the conditions specified in the fusing characteristics specifications. Next, remove the dummy resistor, attach the test resistor _R1 , and switch S
Put in. After turning on the switch, use an ammeter to check whether the specified current is flowing. If the current is not the specified value, quickly (within 1 second) make fine adjustments. However, the power supply will not be adjusted after that point. Then, measure the time from when the switch is turned on until the wire breaks. In addition, the determination that the resistor has reached the disconnection state is made when the current value is 1/50 of the initial test current.
Perform with the following conditions. The results are shown in FIG. Here, the material of the thermosoftening resin layer 6 includes, for example, rosin, olefin, styrene,
Examples include nylon-based, phenol-based, xylene-based resins, and modified products thereof. In the above embodiment, as shown in FIG. 2a, after forming three types of resistance films indicated by numerals 2 to 4 on the surface of the insulating substrate 1, heat treatment is performed to form an alloy resistance film 3.
As described above, in the step shown in FIG. 1, after forming the Sn layer, Pb layer or Sn-Pb alloy film layer [a-1], the heat treatment step is carried out as shown by the broken line. Even if [a-2] is omitted and the subsequent steps are performed, the resistor of the present invention can obtain the same effect as described above. Also, at this time, it goes without saying that the groove cutting step [a-3] for modifying the resistance value may be performed as necessary. Furthermore, in this example, Pb
The case of forming a -Sn-Ag alloy resistance film has been described in detail, but as mentioned above, the same effect as this example can be obtained with a resistance film obtained from the 24 combinations of films as described above. be. As described above, the overload fusing type resistor of the present invention has the following features:
Both have a low power multiplier, stably and accurately cut off current, and can be an overload fusing type resistor that has performance and reliability equivalent to general resistors during rated operation. In addition, examples of fusing type resistance coatings include:
One of tin, lead, bismuth, cadmium, indium, and the above tin, lead, bismuth, cadmium, indium, and further silver, copper, zinc,
It is conceivable to use two or more alloys of aluminum, etc., but each of the manufacturing methods of the present invention is practical because it is relatively easy to form a film, the manufacturing cost is low, and it is suitable for use as a resistor. The silver mirror method, which can fully guarantee the reliability of Sn
After a surface treatment such as electroless plating, a Sn, Pb, or Pb-Sn alloy resistance film is deposited and produced by a plating method to realize the above-mentioned overload fusing type resistor. Further, by forming a thermosoftening resin layer on the resistive film, the fusing characteristics can be further improved, and a product with a high withstand voltage after fusing can be obtained. Moreover, since the manufacturing method of the present invention can utilize the conventional manufacturing process of film resistors as is, it can be provided at a low cost.

[Brief explanation of drawings]

Figure 1 is a manufacturing process chart for the product of the present invention, Figure 2
Figures a and b are cross-sectional views before and after heat treatment in the process of manufacturing a resistor according to the present invention, Figure 3 is a cross-sectional view after forming a thermosoftening resin layer, Figure 4 is a cross-sectional view of the main parts of the entire resistor, FIG. 5 is a diagram of the fusing characteristics, and FIG. 6 is a circuit diagram of the fusing characteristics test. DESCRIPTION OF SYMBOLS 1...Insulating substrate, 2...Activation treatment layer of Sn layer or Ag layer, 3...Ag layer or Sn layer, 4...Solder layer, 5...Pb-Sn-Ag alloy resistance film, 6...
...Thermosoftening resin layer, 8...Groove cut portion.

Claims (1)

[Claims] 1. A first layer consisting of a Sn layer or an Ag layer is formed on the surface of an insulating substrate by activation treatment, and an Ag layer, a Sn layer, or any of them is formed on this by a silver mirror method, an electroless plating method, etc. A second layer consisting of a mixture layer of
Then, a Sn layer, a Pb layer, or a Sn-
A third layer made of a Pb alloy is deposited by electroplating to form a resistive film, and a heat-softening resin layer is formed on the resistive film so as to partially or entirely cover the resistive film, including the center. A method for manufacturing an overload fusing type resistor in which the entire resistor is covered with an insulating material such as a heat shrink tube. 2. The method for manufacturing an overload fusing type resistor according to claim 1, which comprises the step of cutting grooves for resistance value correction after forming the resistance film. 3 A first layer consisting of a Sn layer or an Ag layer is formed on the surface of the insulating substrate by activation treatment, and then an Ag layer, a Sn layer, a layer of a mixture thereof, or a mixture thereof is formed on this by a silver mirror method, an electroless plating method, etc. A second layer consisting of a laminate layer of 1 μm in thickness with an electrical resistance value in the range of 0.1 to 15 Ω for any of the metals.
Then, a Sn layer, a Pb layer, or a Sn-
A third layer made of a Pb alloy is deposited by electroplating to form a resistive film, and then the resistive film is heat-treated, and then a portion or the entirety of the resistive film is deposited on the resistive film, including the central part of the resistive film. A method of manufacturing an overload fusing type resistor, in which a heat-softening resin layer is formed to cover the overload resistor, and the entire body is covered with an insulating material such as a tube.