JPS61166006A - Adjustment for resistance value of film resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a film resistor in which a resistance film of carbon, metal, etc. is deposited on an insulating substrate such as an insulator. The present invention relates to a method for adjusting the resistance value of a film resistor.

2. Description of the Related Art Conventionally, this type of resistance value adjustment has been carried out by a method as shown in FIG. That is, both ends of a film resistor 1, which is a cylindrical insulator with a resistance film coated on its surface, are gripped by chucks 2, the film resistor 1 is rotated and fed in the axial direction, and a thin disk-shaped cutting wheel 3 is attached to it. By applying the material while rotating it at high speed, a spiral groove was formed and the resistance value was adjusted (this is called trimming). In addition, in Fig. 3, 4 is a spindle consisting of a shaft 4a and a bearing 4b,
It functions to rotate the grindstone 3 mentioned above. Reference numeral 5 denotes a cutter holder that houses the spindle 4, and the spindle 4 is rotationally driven by a motor 6, a large/small pulley 8, and a belt 9.

As a method of applying the cutting whetstone 3 to the film resistor 1, a configuration as shown in FIG. 4 has been common.

That is, the cutter holder 6 containing the spindle 4 that rotates the cutting wheel 3 is supported by the fulcrum 1o, the position of the weight 11 is adjusted to adjust the force with which the cutting wheel 3 is pressed against the film resistor 1, and the cam 12 is used to perform cutting. The timing was right to apply the grindstone 3 to the film resistor 1. Further, in FIG. 4, 13 is a cutter holder holder, 14 is a weight shaft, 15 is a cam lever, and 16 is a fulcrum.

In this adjustment method, in order to generally cut a good groove, the rotating surface of the cutting wheel 3 is set at an angle of 0 with respect to the film resistor 1, as shown in FIG.
I adjusted it to match 7.

Problems to be Solved by the Invention The conventional resistance value adjustment method generally used has the following problems.

(1) Grooves are formed by applying a high-speed rotating cutting wheel to the film resistor, which applies thermal and mechanical stress to the film resistor, leaving fine cracks on the edges of the groove.
These factors become a factor in the deterioration of electrical characteristics. Furthermore, as the temperature of the film resistor increases, the resistance value becomes different from that at room temperature due to the temperature characteristics of the resistance film, which tends to cause a resistance value measurement error when adjusting the resistance value.

(2) As shown in Fig. 4, since the contact between the cutting edge of the cutting wheel 3 and the film resistor 1 is made only by the weight of the cutter holder 6, etc., the tip of the cutting edge tends to precipitate, especially at the start of grooving. The groove depth and groove width vary. Additionally, if the cutting wheel bounces on the film resistor, it will cause groove jumping. These things cause deterioration of the electrical characteristics of the film resistor that has become a product.

(3) In order to prevent groove skipping and groove defects mentioned in item (2) above,
It is necessary to press the cutting wheel against the film resistor with more force than a certain level, which results in the formation of a deep groove of several micrometers. Figure 6 shows this situation, and 18
Vi is the deep groove mentioned above. As shown in FIG. 6, the thickness of the portion of the resistance film 2o existing on the surface of the insulator 190 constituting the film resistor 1, including the surface roughness of the insulator 19, is less than Thm. Therefore, the mechanical bending strength of the resistor body is extremely reduced due to the deep groove 18 described above. This is undesirable because it may cause the film resistor to break, for example, when the film resistor is inserted into a printed circuit board using an insert machine. Also, by cutting the insulator deeply, a large amount of insulator dust made of alumina etc. is generated, but this dust is not only harmful to the human body, but can also clog the precision parts of other machines and prevent normal operation. It becomes a factor that inhibits function.

(4) When the diameter of the cutting wheel becomes smaller due to wear, the condition of the groove deteriorates and the cutting resistance value changes due to the timing difference between the start and end of cutting, so it is necessary to adjust the position of the cutter holder. , resulting in a decrease in productivity.

(5) As shown in Figure 6 above, since the edges of the grooves are sharp, it is easy to damage the resistance coatings of other film resistors and the plating of terminal caps during product transportation, and the edges of the grooves themselves The resistance value may change due to chipping, or the plating of the terminal cap of another film resistor may adhere to the resistance film, deteriorating the electrical characteristics.

(6) Failure to insert the film resistor into the chuck,
If the film resistor rotates eccentrically due to eccentric chucking, an impact will be applied to the cutting edge of the cutting wheel, causing part of the blade to chip. If a part of the blade is chipped in this way, the condition of the groove will deteriorate significantly, and if production continues without noticing, a large number of defective products will be produced.

(7) If the cutting wheel wears beyond a certain level or becomes clogged, it needs to be dressed or replaced, and this requires fine adjustments, which limits the ability to increase productivity.

(8) Since it is possible to adjust the resistance value of only one film resistor held by chuck using one cutting wheel,
The number of products produced per unit time is small.

(9) In order to cut a good groove, set the rotating surface of the cutting wheel so that it makes an angle of 0 along the spiral groove with respect to the film resistor, as shown in Figure 5, and then cut a trial groove. The inclination of the film resistor with respect to the axial direction must be finely adjusted during the process, and it is necessary to rely on skilled workers. Also,
If the adjustment is insufficient, not only will the condition of the groove deteriorate, but also the life of the cutting wheel will be shortened. Therefore, in order to solve the above problems, the present invention uses a cutter that does not change much over time. By scraping off only the resistive film, the stress on the film resistor and the amount of dust generated are reduced.

Means for solving the problem In order to solve this problem, the present invention uses a thread-like abrasive material made by adding abrasive grains to the raw material or adhering it to the surface of the raw material.
It is equipped with a pulley and a drive device that causes it to run at a predetermined speed while giving a predetermined tensile strength to the resistor, and has a configuration in which a plurality of film resistors are gripped and rotated by a chuck having a plurality of sets, and the thread-like abrasive material is applied to them; and at least one of the queen film resistor and the thread-like ground material is moved in the axial direction of the film resistor, and a spiral groove is cut in the resistance film of the film resistor to adjust the resistance value. That is.

Function: According to this configuration, the resistance film is partially scraped off using a thread-like abrasive material, so it is only necessary to scrape off a shallow portion of the surface of the film resistor, and the running speed of the abrasive material is also lower than that previously used. Since a circumferential speed of about i/10 of the cutting wheel is sufficient, there is almost no temperature rise in the grinding part, so no thermal stress is applied to the resistor. Further, mechanical stress such as fine cracks does not remain on the edge of the groove. Due to these factors, the electrical characteristics will not deteriorate. Also,
Since the abrasive object can be easily moved without leaving the surface of the film resistor, groove jumping does not occur, and if the tension applied to the abrasive object, running speed, and pushing amount are controlled at a constant level, the groove depth can be adjusted. Groove conditions such as the sheath groove width remain unchanged over time, and electrical characteristics are maintained well.

Furthermore, as mentioned above, since the grooves cut out are shallow,
The mechanical bending strength of the resistor body does not deteriorate, and the product will not be damaged by impact when inserted into the board with an insert machine. Since only a shallow portion of the surface of the film resistor is scraped, the insulator is hardly scraped, and as a result, the amount of dust on the insulator is extremely reduced. Further, since a large number of film resistors held by a large number of chucks can be adjusted simultaneously using a single thread-like grinding object, productivity per unit time can be increased.

Embodiment 1 An embodiment of the present invention will be described with reference to the drawings.

First, in Fig. 1, reference numeral 21 indicates an abrasive thread as a filament-like abrasive material made by adding abrasive grains to the raw material or adhering them to the surface thereof, such as nylon (trade name of DuPont), which is a polyamide-based synthetic polymer. Silicon carbide is bonded to the surface of the 22 is a cylindrical film resistor with a resistance film coated on its surface. Then, the film resistor 22 is grabbed by the right chuck 23a sent in the axial direction by the feed cam 26 and the right chuck 23b supported by the spring 28.
It is caused to revolve together with the disk 24 (angular velocity W2). on the other hand,
By rotating the large gear 26 slightly slower than the disk 24 (angular velocity W1), the small gear 27 rotates (angular velocity W3) and the film resistor 22 rotates. Above feed cam 2
6 pushes the chuck 23a, and the film resistor 22 is sent in the axial direction. Chuck 2 with the same mechanism as above
A large number of sets of 3a123b are provided to continuously supply film resistors 22. The abrasive thread 2 is attached to the crest of the disk 24, which has many valleys on the outer circumferential surface in which the film resistors 22 are housed.
The abrasive thread 21 is driven by a drive device such as a motor (not shown) along which the abrasive thread 21 guides the IJ-29 and IJ-30, which are arranged vertically at a predetermined speed. Run through. Also, Boo IJ-
Appropriate tension is applied to the abrasive thread 21 by means of 29 and 30.

With the above mechanism, the abrasive thread 21 is connected to a large number of film resistors 2.
The resistance value can be adjusted by continuously cutting grooves into the resistive film No. 2 in a spiral shape.

FIG. 2 is a diagram showing the condition of the grooves of a film resistor whose resistance value has been adjusted in this way.A shallow groove 31 is formed on the surface of the resistor, and this shallow groove 31 is approximately #1. Only the resistive film 32 is scraped off, and the surface of the insulator 33 is only shallowly scraped off.

Furthermore, in the above embodiment, a case has been described in which a part of the resistance film 32 on the film resistor 22 is cut off by the abrasive thread 21 by feeding the film resistor 22 in its axial direction. The polishing thread 21 is connected to the film resistor 22.
Alternatively, both the abrasive thread 21 and the film resistor 22 may be moved.

As described above, in the resistance value adjustment method of the present invention, a large number of film resistors 22 are
, and press the abrasive thread 21 running at a predetermined speed while applying a predetermined tension onto the film resistor 22, and at least one of the abrasive thread 21 or the film resistor 22 is attached to the axis of the film resistor 22. This is a novel and unprecedented technical means in which the resistance value is adjusted by scraping off the resistance film 32 at an arbitrary portion on the film resistor 22 and cutting a spiral groove by moving the resistor film 32 in the direction of the film resistor 22.

Effects of the Invention The effects obtained by the method for adjusting the resistance value of a film resistor according to the present invention configured as described above are as described below.

(1) It is only necessary to scrape off almost only the resistance film on the surface of the film resistor, that is, only the shallow part, using the abrasive thread (thread-like grinding material), and the running speed of the abrasive thread is 1/2 the circumferential speed of the conventional cutting wheel. Since a speed of about /1o (approximately 300 m/min) is sufficient, there is almost no temperature rise in the grinding part. Therefore, no thermal stress is applied to the resistor, and no measurement error occurs when adjusting the resistance value. Further, mechanical stress such as fine cracks does not remain on the edge of the groove.

Due to these factors, the electrical characteristics will not deteriorate.

(2) Since the abrasive thread can be easily run without leaving the surface of the film resistor, groove jumping does not occur, and if the tension applied to the abrasive thread, running speed, and pushing amount are controlled at a constant level, Groove conditions such as groove depth and groove width remain unchanged over time, and the electrical characteristics of the product are maintained well.

(3) In order to adjust the resistance value of a film resistor, it is only necessary to scrape away the portion (thickness) of the resistor surface where the resistance film is present, but if abrasive thread is used, shallow grooves can be ground as described above. Easy to use. Since the groove cut out in this manner is shallow, the mechanical bending strength of the resistor body does not deteriorate, and the product will not be damaged by impact when inserted into a board with an insert machine. In addition, since only a shallow portion of the surface of the film resistor is scraped, the insulator is hardly scraped, and as a result, the amount of dust generated on the insulator is extremely reduced.

(4) As the abrasive thread runs, new parts come into contact with the resistor surface one after another, so the stiffness of the abrasive thread remains unchanged over time and the groove condition does not deteriorate.

(6) As shown in Figure 2, the edges of the grooves do not become sharp, so they are less likely to damage other resistors or the edges of the grooves themselves are chipped. Prevents deterioration.

(6) Even if the film resistor fails to be inserted into the chuck and the film resistor rotates eccentrically, the abrasive thread can move freely according to the movement of the film resistor, so there is no chance of damage to the abrasive thread. There isn't.

(7) Since only the shallow part of the surface of the insulator is scraped off, there is little wear on the abrasive threads, and when replacing them, only the abrasive threads need to be replaced, and no detailed adjustments are required. Therefore, in addition to the above points (5) and (6), productivity can be increased.

(8) The resistance values of multiple film resistors held by multiple sets of chucks can be adjusted simultaneously with one polishing thread.

(9) Even if one or both of the abrasive thread and the film resistor are simultaneously moved in the axial direction of the film resistor while the abrasive thread is applied to the film resistor being rotated, a spiral groove will be formed in the same way. This allows for a high degree of freedom in device design. In addition, it is much easier to adjust the abrasive thread so that it forms an angle of 0 along the spiral groove with respect to the film resistor than with conventional cutting wheels, and even non-skilled workers can easily adjust it. You can easily cut grooves.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a method for adjusting the resistance value of a film resistor according to an embodiment of the present invention, FIG. 3
The figure shows the method of adjusting the resistance value of a conventional film resistor.
The figure is a perspective view showing an example of a mechanism in which a cutting wheel is applied to a film resistor in the conventional method. FIG. 6 is a diagram showing that the cutting wheel and the film resistor make an angle of 0 in the conventional method. FIG. 2 is an enlarged cross-sectional view of the surface of a resistor showing the state of kerfs obtained by a conventional method. 21... Polishing thread, 22... Film resistor, 23a... Left chuck, 23b...
Right chuck, 24... Disc, 25...
...Large gear, 26...Feed cam, 28...
...Spring, 29 e 30...Pulley, 31
...Shallow groove, 32...Resistance film, 33
······insulator. Figure 3 Figure 4

Claims (1)

[Claims] Abrasive grains are added to the raw material and a thread-like abrasive material is bonded to the surface of the material.It is equipped with a pulley and drive device that runs at a predetermined speed while applying a predetermined tension to the thread-like abrasive material. The film resistor is gripped and rotated while the thread-like ground material is applied to the film resistor, and at least one of the film resistor and the thread-like ground material is moved in the axial direction of the film resistor, and the film resistor is rotated. A method for adjusting the resistance value of a film resistor, characterized by adjusting the resistance value by cutting a spiral groove in the resistance film of the resistor.