JP3648465B2 - NTC thermistor for temperature detection and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, fan heaters, refrigerators, air conditioners, vending machines, electric kettle, an electro toilet seat and various electrical及beauty temperature sensing NTC thermistor and a manufacturing method thereof are equipped with electronic devices that operate at a temperature control system Is.
[0002]
[Prior art]
Conventionally, an NTC thermistor used for a temperature detection sensor has used a pellet type NTC thermistor element having an end electrode having an electrode on a main surface. Hereinafter, the pellet type NTC thermistor is referred to as a pellet.
[0003]
The temperature detecting NTC thermistor (hereinafter simply referred to as the thermistor) will be described with reference to FIGS. FIG. 5 is a perspective view showing the structure of a conventional commercially available thermistor that is commercially available, and FIG. 6 is a front view showing a conventional thermistor element or pellet mounting structure, schematically showing the pellet holding structure of FIG. It can also be said to be a figure.
[0004]
As shown in FIG. 5, the conventional thermistor divides the pair of two-core wire ends 4 and 5 arranged in parallel with one end of the two-core insulation-coated electric wire 1 into two equal parts from a flat direction having a large axis. The pellets are fixed by dipping or jet soldering while the pellets 7 are sandwiched between the normal processed left core wire 4 and the normal processed right core wire 5 which are formed into a cracked shape facing each other. Then after drying with tempering Do dipping the insulating paint coating or insulating coating covers the entire tip insulator, and a product.
[0005]
A schematic diagram of the portions constituting the opposing bowl-like shapes is displayed in FIG. The pellet 7 is sandwiched between the normal processed left core wire 4 and the normal processed right core wire 5, but is not fixed at the beginning.
[0006]
Before the thermistor is completed, in order to electrically fix the pellet 7 to the core wires 4 and 5 holding the pellet 7, (1) Dip into the flux solution or the melted flux solution, which is performed for flux coating before soldering. There are processes and (2) a process of immersing in a molten solder tank or passing a solder jet. In the step of (1) and (2), the form of being upside down in FIG. 6.
[0007]
Accordingly, in these steps (1) and (2), the pellet 7 sandwiched between the normal processing left core wire 4 and the normal processing right core wire 5 falls down by gravity and falls into a flux tank or molten solder. Or remain in the tank. In addition, a situation in which the flux jets or the solder jets flow out occurs.
[0008]
In order to eliminate these productivity-inhibiting factors, it is necessary to lightly press and hold with a dedicated clip, temporarily tap, or place in a chucking jig before flowing to the steps (1) and (2). The attachment process, that is, the attachment to the temporary fixing jig, the removal or removal process of these props, and the originally undesired processes before and after the soldering process have been required.
[0009]
Further, the (2) soldering solder used for bonding the two core 4 and 5 and the pellets 7 in step to body surface of the pellet 7 as solder traces 9s indicated by a dotted line in FIG. 6 and and its The area is indefinite. However, in the case of the temperature detection sensor using the pellet 7, the resistance value changes because the distance between the electrodes decreases by soldering, and the resistance value does not fall within the standard range as a product, resulting in a defect. As a result, the product yield deteriorates.
[0010]
In addition to this, due to the expansion and contraction of the wire coating and insulation paint due to temperature changes after shipment as a product, the soldered pellet 7 element and the electrode that determines the resistance value peel off, and the electrical characteristics The resistance value changes or, in the worst case, it becomes an electrically non-conductive state, resulting in a defective part.
[0011]
As described above, it has been difficult to provide a temperature detection sensor using a pellet type NTC thermistor and soldered to a two-core parallel insulation coated electric wire as a highly reliable electronic component.
[0012]
[Problems to be solved by the invention]
The present invention provides an NTC thermistor for temperature detection with excellent work efficiency and high productivity and reliability, and a method for manufacturing the same, in order to solve the above-described problem of dropping the pellet or thermistor element from between the core wires due to gravity. Objective.
[0013]
[Means for Solving the Problems]
An NTC thermistor for temperature detection according to the present invention is an NTC thermistor for temperature detection in which a thermistor element is connected to one end of a core wire of a two-core parallel insulation coated electric wire and a resin-molded covering portion is provided . The base end portion is substantially parallel, bent in a direction in which the distance increases from the base end portion to the intermediate portion, then bent in a narrowing direction, and bent so as to be substantially parallel at the tip end portion. A laminated chip thermistor element having a rectangular parallelepiped shape and having external electrodes formed at both ends in the longitudinal direction, and the parallel tip inner surfaces of the pair of bare core wires are shaped to match the external electrode shape of the laminated chip thermistor element it is, wherein said both ends to said laminated chip type thermistor element so that the external electrode portion is in close contact is being sandwiched between the parallel distal portion of the pair of bare wire It is intended to. The invention according to claim 2 is characterized in that the ends of the pair of bare core wires are formed in a groove shape .
[0014]
In addition, the manufacturing method of the temperature detecting NTC thermistor of the present invention connects a laminated chip thermistor element having external electrodes at both longitudinal ends of a rectangular parallelepiped to one end of a core wire of a two-core parallel insulation coated insulated wire, and a resin. The temperature detecting NTC thermistor is provided with a covering portion coated with a base portion , the base end portion is substantially parallel, and the rear end portion is bent outward and inward from the base end portion to the intermediate portion. A pair of bare core wires that are substantially parallel and have a leading edge formed in a groove shape are prepared, and the laminated chip type thermistor element is inserted from the direction of the groove leading edge portion of the pair of bare core wires. The method includes a step of pressing and sandwiching the laminated chip type thermistor element by bringing both end external electrodes into contact with each other.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The adverse prevention by the aforementioned solder traces 9s, was compatible with 6 a · 6b product layer N TC thermistor element 6 as an external electrode of FIG. 2, the soldering process placement or desorption step for temporarily fixing jig before and after It remained as it was. In order to distinguish the multilayer chip type NTC thermistor element 6 which can be called an improved version of the pellet 7 from the pellet 7, it will be called the thermistor element 6 below.
[0016]
However, since the thermistor element 6 is externally the same shape as the pellet 7, it is synonymous with the pellet 7 referred to in FIGS. 5 and 6 in terms of shape and function, but the adverse effect of the solder trace 9s can be prevented. (Details of this will be described later). Therefore, when the thermistor element 6 is used in combination with the conventional core wires 4 and 5, it is still necessary to attach or detach the temporary fixing jig before and after the soldering process. However, although there is no change in the structural requirements as a temperature sensing thermistor, the present invention aims to eliminate the cause of trouble due to the conventional core wire shape. Therefore, the following description is based on the solder trace 9s instead of the pellet 7. The description is changed to the description using the thermistor element 6 in which the adverse effect is eliminated.
[0017]
The configuration of the temperature detecting NTC thermistor of the present invention will be described with reference to the perspective view of the configuration of the NTC thermistor of the present invention shown in FIG. A core wire, which is a pair of bare lead wires extending in parallel from one end of the two-core insulation-coated electric wire 1, is positioned as a processed left core wire 2 of the present invention and a processed right core wire 3 of the present invention and has a groove at the tip. The inner surface of the thermistor element 6 is formed into a flattened shape, and the parallel surface portion formed in accordance with the size of the thermistor element 6 is formed into a shape corresponding to the electrode shape. Are connected and integrated by a mold covering portion 8 having a rounded rectangular parallelepiped shape indicated by an imaginary line.
[0018]
Also, as can be referenced in NTC thermistor element mounting portion front view of the present invention in FIG. 3, is in being included integrally with Sumimaru flat rectangular mold cover portion 8 shown in phantom, flat surface of FIG. 1 In the figure , one of the core wires which are a pair of bare lead wires extending in parallel from one end of the two-core insulation-coated electric wire 1 is the left-core wire 2 which has been molded according to the present invention. forms a parallel plane to the base normal axis combined bent or curved above the outside in the form of the external electrodes 6 a of the thermistor element 6 forming the long rectangular when Mitateru, having internal electrodes of the thermistor element 6 opens the previously outwardly fit the shape of the external electrode 6 b which opposed to the opposite side through the body 6c which also forms a parallel plane to the base normal axis, are open beyond the outer side. The base side is opposed to the molded right core wire 3 of the present invention that is bent or curved outward so as to be symmetric to the processed left core wire 2 of the present invention.
[0019]
Accordingly, the two thermistors 2 and 3 are flat so that the thermistor 6 can be sandwiched by a plane portion that is nearly parallel from the open tip (formed in a shape that matches the electrode shape) while forming a bent or curved shape inside and outside. It extends from the base two-core insulation-coated electric wire 1 so as to form a stagnation.
[0020]
The reason why the thermistor element 6 is drawn in phantom lines in FIG. 3 is that there is a slight difference in the longitudinal dimension of the thermistor element 6 depending on the purpose of use, and the thermistor element 6 has two external electrodes 6a and 6b and an internal part. It shows that it consists of three layers of the element body having the electrode 6c.
[0021]
1 and 2, the sandwiching width of the thermistor element 6 is characterized in that it is a flat surface in which the width of the rear end portion and the width of the front end portion are equal, and is formed in a shape that matches the electrode shape. This enhances the reliability of holding the temperature detecting NTC thermistor and increases the strength against an external load. This will be described with reference to the front view of the thermistor mounting portion of the present invention before coating shown in FIG.
[0022]
The processed core wires when the thermistor element is not inserted indicated by a two-dot chain line are a pair, the left core wire 2c1 and the right core wire 3c1 face each other symmetrically, and the interval for forming the parallel flat portion when the thermistor element 6 is held is Since the thermistor element 6 is slightly narrower than the sandwiched width, they face each other with a slightly tapered gradient. Therefore, the pair of processed core wires shown by the solid line when the thermistor element 6 is held is in close contact with the shape of the left core wire 2c2 and the right core wire 3c2 which face each other in a symmetrical manner and match the electrode shape of the outer end portion of the thermistor element 6. This is because the left and right core wires are widened by inserting the thermistor element 6 and, as a reaction, elasticity is generated in the direction of the arrow 10 shown in the figure, so that the thermistor element 6 is held with a holding force corresponding to the elasticity.
[0023]
Therefore, the holding force can be set significantly compared to when using the core wire, which has been auxiliary in positioning of the thermistor element or pellet and has almost no holding force, which makes it possible to fix the position in the flux application process and soldering process. Or since an auxiliary tool becomes unnecessary, it is not necessary to set a prior holding support process and a subsequent holding release or removal process. Therefore, productivity can be improved.
[0024]
Further, as described above, the thermistor element 6 is formed by forming two external electrodes 6a and 6b, which are end electrodes familiar with solder, on both sides of the element body 6c. For this reason, when immersed in a solder ring dip bath or a wave-shaped molten solder, the molten solder flows toward the external electrodes 6a and 6b having good solder wettability, and the surface of the element body 6c having a low surface tension of the molten solder is applied. Solder is difficult to spread.
[0025]
For this reason, in the soldering process, even if the solder is deeply immersed in an upside down posture as shown in FIG. 3, the solder is good between the left core wire 2, the external electrode 6 a, the external electrode 6 b, and the right core wire 3. Although the solder fillet 9 is formed, it is difficult to join the left core wire 2 or the right core wire 3 to the surface of the element body 6c. Therefore, if the temperature and the number of seconds, which are the conditions for dipping the solder bath in the soldering process, are optimized, the generation of the solder trace 9s can be set to be zero.
[0026]
This action, since not occur to reduce the surface area of the element body by soldering, since the fluctuation factors in the resistance value is eliminated, it can be maintained without impairing the reliability of the design Initial.
[0027]
Next, the manufacturing process of the temperature detecting NTC thermistor of the present invention is shown in FIG. The embodiment will be described below with reference to FIG. In FIG. 4A, one end of the two-core insulation-coated electric wire 1 is an unformed processed left core wire 2a and an unformed processed right core wire 3a, which are only bare core wires with the covering exposed to an appropriate length.
[0028]
Next, a process in which most of the bare core wire except the base portion is subjected to intermediate molding in a thin flat plate shape toward the tip is shown as an intermediate molded left core wire 2b and an intermediate molded right core wire 3b in FIG. Show. As the forming proceeds, the shape shown in FIG. 2 is obtained, and a formed left core wire 2c and a formed right core wire 3c are formed as shown in FIG. 4C.
[0029]
FIG. 4D shows a process in which the laminated chip type NTC thermistor element 6 is inserted into the gap formed by the molded left core wire 2 and the molded right core wire 3 on the external electrode surface. The flux application process may be performed before or after this process, and is not shown.
[0030]
Figure 4 (E) shows a just half rattling only, the thermistor element 6 shows a step of electric fixation is completed as solder dip already thermistor 9t.
[0031]
Depending on the flux used, a cleaning step may be required after this step, but this is not an inevitable step, and thus illustration is omitted.
[0032]
Last figure 4 (F) is the (E) after the step, both partially distally of the distal end portion the wire two-core insulated wire 1, is formed form a thermoplastic resin rounded tabular, etc. with the mold It becomes the coating 8, and the manufacturing process in a narrow sense is completed. Depending on the resin used for the mold coating, a heat treatment step for curing may be required after this, but this is not shown.
[0033]
This last step also solves the problem of characteristic change due to temperature change after manufacture. By adopting the core wire having the shape of the present invention and the above-described manufacturing method, productivity can be greatly improved and quality deterioration due to secular change can be prevented, so that high reliability can be maintained for a long time.
[0034]
【The invention's effect】
According to the present invention as described above, it is easy to fix the position at the time of insertion work between core wires for thermistor insertion, increase the posture holding force of the thermistor after insertion between the core wires, and between the manufacturing steps of the thermistor In order to prevent the thermistor from falling off between the core wires, a manufacturing method that increases productivity could be developed.
[0035]
In addition, a highly reliable temperature detecting NTC thermistor can be provided to the market by stabilizing the solderability in the manufacturing process by combining the core wire shape and the laminated chip type NTC thermistor element, and preventing the deterioration over time by the mold coating.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of an NTC thermistor according to the present invention.
FIG. 2 is a front view of the NTC thermistor element mounting portion of the present invention.
FIG. 3 is a front view showing a thermistor mounting portion before coating according to the present invention.
FIG. 4 is a diagram showing a manufacturing process of the thermistor of the present invention.
(A) The tip of the electric wire from which the core wire from which the coating has been removed is exposed is shown.
(B) The state where the tip of the core wire is formed in a flat rectangular shape is shown.
(C) The state where the tip is completed in the shape of the present invention is shown.
(D) A process of inserting an NTC thermistor at the tip.
(E) The tip is soldered.
(F) The finished shape with the tip covered with thermoplastic resin molding is shown.
FIG. 5 is a perspective view showing a configuration of a conventional thermistor.
FIG. 6 is a front view showing a conventional thermistor element mounting structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Two-core parallel insulation covering electric wire 2 Molded left core wire 3 Formed right core wire 4 Formed right core wire 4 Processed left core wire 5 Processed right core wire 6 Multilayer chip type NTC thermistor element 7 Pellet 8 Mold coating part 9 Solder fillet 9s Solder trace 9t Solder dipped thermistor

Claims (3)

An NTC thermistor for temperature detection in which a thermistor element is connected to one end of a core wire of a two-core parallel insulation coated wire and a resin-molded coating portion is provided,
The pair of bare core wires are bent in a direction in which the base end portions are substantially parallel and are widened from the base end portion to the intermediate portion, then in a narrowing direction, and are bent so as to be substantially parallel at the tip end portions. Become
The thermistor element has a rectangular parallelepiped shape, and is a laminated chip type thermistor element in which external electrodes are formed at both ends in the longitudinal direction.
The parallel tip inner surfaces of the pair of bare core wires are shaped to match the external electrode shape of the multilayer chip thermistor element,
The temperature detecting NTC thermistor, wherein the laminated chip thermistor element is sandwiched between the pair of bare core wires so that the external electrode portions are in close contact with each other between the parallel tip portions. 2. The temperature detecting NTC thermistor according to claim 1, wherein tips of the pair of bare core wires are formed in a groove shape. A temperature sensing NTC thermistor in which a laminated chip type thermistor element having external electrodes at both ends in the longitudinal direction is connected to one end of a core wire of a two-core parallel insulation coated insulated wire, and a covering portion coated with a resin is provided. The base end portion is substantially parallel, bent outward and inward from the base end portion to the middle portion, and then the tip end portion is made substantially parallel and the most advanced portion is formed in a groove shape. A pair of bare core wires is prepared, and the laminated chip thermistor element is inserted from the direction of the grooved leading end of the pair of bare core wires, and both end external electrodes of the laminated chip thermistor element are connected between the tip parallel parts. The manufacturing method of the temperature detection NTC thermistor characterized by including the process of carrying out pressure clamping by making it contact .

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