JPH0247803A - Manufacture of film resistor - Google Patents

Abstract

PURPOSE:To equalize the deposit of solder and strengthen the strength of a solderability by performing electrolytic plating by a rotary barrel to the terminal section of a resistor having used not a metal cap but a film with a high resis tance value. CONSTITUTION:When resistor elements whose resistor films are partly coated with insulating coats and media are put in a rotary barrel in a volume ratio of an extent of from 10 to 1 to 10 to 2 and electrolytically plated, the cathode comes into much more contact with the film parts of the resistor which have not been coated with the insulating coats, through the media. With the rotation of the barrel, the lowest lumpy layer is raised along the inside wall of the barrel, and then falls rotating on the upper lumpy layer when the barrel rotates. In this way, the lumpy articles circulate in order repeating this motion. In this electric barrei plating method, the weight Wm of the medium is heavier than that Ws of the resistor element, and the diameter Dm of the medium is 1.2 times as large as the diameter Ds of the resistor element, or smaller. Besides, the length Lm of the medium is 2 times as long as the length Ls of the resistor element or shorter, and besides is longer than the diameter Dm of the medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a chip-shaped film resistor in which terminal portions are electro-barrel plated.

[Conventional Technique T4j] Chip-shaped film resistors are used in electronic circuits such as televisions, radios, communication devices, or electrical measuring devices, and are required to have stability and reliability.

Alternatively, metal cap terminals are fitted to both ends of a resistor element in which a carbon, metal, or metal oxide film is formed on the surface of a cylindrical carrier of an insulating ceramic, such as alumina-based porcelain. Then, cut the film between the cap terminals into a spiral shape, adjust the film between the cap terminals to the specified resistance value, and then cover the cap terminals with an insulating resin to make it moisture-proof, insulating, and heat-resistant. In addition to providing impact resistance, the surface of the metal cap is soldered by electrolytic barrel plating to improve connectivity to the circuit board.

However, there is an increasing demand for miniaturization of resistors, and resistors that are small and have high resistance values are desired.

In order to meet this demand, the sheet resistance value of the resistive film can be increased by removing the metal cap, changing the composition of the resistive film, or making the resistive film thinner. As a result, a small, high-resistance resistor has been obtained.

A high-resistance resistor element with the metal cap removed.

The coating on both ends of the porcelain carrier is coated with Cu by electroless plating.
, Ni, etc. are plated, and solder is further applied thereon by barrel plating method to improve the solderability of the connection terminals.

How to manufacture film resistors without using metal caps.

For example, Ni-
A resistive film is formed on the surface of the ceramic carrier by vapor-depositing or sputtering a Cr alloy or a metal such as Ni or Cr9.Next, a plating resist is applied around the circumferential surface of the central portion of the resistor element and hardened. Then, Cu or Ni is electrolessly plated on the resistive film on both end faces of the resistor element and the peripheral face continuous thereto, thereby forming connection electrodes.

Next, the plating resist is peeled off, the reconnection electrodes of the resistor element are held, and the resistance film on the circumferential surface of the central portion of the resistor element is cut in a spiral shape to form a predetermined resistance value between the reconnection electrodes. are doing.

Thereafter, an insulating resin is again applied to the circumferential surface of the central portion and cured, and Ni and solder are electrolytically barrel plated onto the connection electrodes to form connection terminals.

In the electrolytic barrel plating method, many through holes are formed in the wall, a cathode is provided in a rotatable barrel, and a material to be plated and media are placed in the barrel.

Separately, a plating solution is placed in a plating tank equipped with an anode. Thereafter, the barrel is placed in a plating bath, and a voltage is applied between the anode and the cathode while rotating the barrel. A plating film is deposited while the object to be plated and the media rotate.

The shape of the media is rod-shaped or spherical, and the size of the media is large enough to sieve the object to be plated, and the weight is less than the same as the object to be plated. The dispersion is made to be uniform.

[Issues to be solved by the invention] It is difficult to perform partial plating using the conventional electroless plating method described above, and even if a skilled person works with great care, the non-plated surface A plating film is likely to precipitate on the insulating resin surface (for example, the insulating resin surface), and partial plating cannot be easily and reliably performed.If the plating film is deposited on a non-plated surface, it may cause a decrease in resistance value or a short circuit.

A resistor that does not use a metal cap and uses a high-resistance film has a high resistance value at the terminals of the resistor element (when electrolytic plating is performed using a conventional rotating barrel, the plating film deposits on the terminals is sparse). Even if solder plating is applied on top of it, the solder precipitation will be sparse and the soldering strength will be weak.
If the plating time is further extended to prevent the plating from becoming sparse, the plating time will increase several times, significantly impairing workability.

It is possible to increase the deposition rate by increasing the current density, but if the deposition rate is increased beyond the i overcurrent density, the overcurrent phenomenon will cause the deposition surface to become There is another problem in that the soldering becomes a non-conductor and impairs the precipitation, and in the conventional method, soldering is strong and it is not possible to provide a small resistor with a high resistance value.

An object of the present invention is to provide a method for manufacturing a film resistor that can solve the above problems by directly performing electrolytic barrel plating on the terminal portion of the resistor using a film with a high resistance value.

[Means for solving the problem] The gist of the means for solving the problem is to form a resistive film on the surface of an insulating carrier, cover a part of the film with an insulating film, and cover the other part with a connecting electrode. The resistor element and the media for assisting the electrical connection of the object to be plated are placed in a rotating barrel equipped with a cathode, immersed in a plating bath equipped with an anode, and the rotating barrel is rotated. At the same time, a voltage is applied between the anode and the cathode, and the connection electrode part of the resistor element is
In the method of electro-barrel plating of low resistance metal, the weight (Wm) of the media is greater than or equal to the weight (Ws) of the resistor element, and the thickness (D tn ) of the media is the thickness (Ds) of the resistor element. It is less than 1.2 times the media length (L
m) is less than twice the length (Ls) of the resistor element and greater than or equal to the thickness (Dm) of the media.

[Operation] Rotating barrel plating is a method in which the object to be plated and the media are mixed in the barrel and plated while rotating.
If the object to be plated and the media are relatively large, the plating solution will penetrate between them and plating will be easy even if they are evenly dispersed. However, if the objects are small, they will remain mixed together and form a lump inside the barrel. This makes plating difficult.

A resistor element whose resistor film is partially covered with an insulating film and the media under the above conditions are mixed at an electric ratio of 10:1 to 1:2.
When electroplating is performed in a rotating barrel at a certain rate, the portion of the resistor film not covered with the insulating film comes into contact with the cathode through the medium under the above conditions.

As the barrel rotates, the bottom lumpy layer is lifted along the inner wall of the rotating barrel, and as the barrel rotates further, it rolls down the top layer.

At this time, due to the 1 liffl difference, although the objects to be plated and the media are mixed, a relatively large amount of objects to be plated are present in the blocky upper layer portion.

As the barrel rotates further, the block hits the barrel wall, the media rides on the object to be plated, and moves to the bottom of the block.

Respectfully repeating this movement, the lumps circulate one after another.

When the media under the above conditions is used, the circulation is repeated while a relatively large amount of the material to be plated remains on the peripheral edge of the block, and the precipitation rate is fastest in the upper layer of the block, followed by the lowest layer.
The precipitation rate is about a fraction of that of the upper layer, and the precipitation rate inside the block is the slowest, about an order of magnitude slower than the precipitation rate of the upper layer.

When the movement between the object to be plated and the media inside the barrel is Ws less than Wm, the object to be plated will mostly stay in the upper layer of the block, and an appropriate amount of media will be mixed, and the media will not be inside the block. This is because the object to be plated can be plated efficiently, even though there is a relatively large amount of plating.

If Ws is heavier than Wm, the above-mentioned condition cannot be obtained, and there is a large amount of media in the upper layer, less material to be plated in the upper layer where the deposition rate is fastest, and the object to be plated is inside the block where the deposition rate is slowest. There will be a lot of things, which is not good.

Also, DM! , 2Ds or less is because when the thickness of the media becomes thicker than 1.2 times the thickness of the object to be plated, the contact condition between the media and the object to be plated becomes poor.

This is because the electrical connection becomes uncertain, the deposition of the plating film becomes unstable, and there are areas where no deposition occurs, which is undesirable. This is preferable because the contact state is good, the electrical connection is reliable, and the plating film is deposited stably and uniformly.

The reason why Lm is set to 2Ls or less is that if the length of the media is more than twice the length of the object to be plated, the mixture of the media and the object to be plated will be poor and the media and the object to be plated will be mixed up in one rotation of the barrel. This is undesirable because the particles separate from each other, making the electrical connection unreliable, making the deposition of the plating film unstable, and leaving some areas where the plating film is not deposited.

If it is less than 2 times, it is preferable because the media and the object to be plated are mixed well, the electrical connection of the object to be plated is easily performed, and the plating film is easily deposited.

The reason why Dm is set to be less than Lm is because if the length of the media is smaller than the thickness, the rolling of the media will be poor, the contact between the media and the object to be plated will be poor, the electrical connection will be uncertain, and the deposition of the plating film will occur. jI under the above conditions, which is unfavorable because it becomes unstable and there are parts that are not precipitated
When meeting, the contact between the media and the object to be plated is good.
Electrical connection is ensured, and the plating film is deposited stably and uniformly, which is preferable.

This will be explained below using examples.

[Example-1] A metal film resistive film was formed on the entire surface of a columnar alumina ceramic carrier having a diameter of 1-0 mm and a length of 1.6 mm by sputtering Ni-Cr, and both end surfaces of the resistor element were coated with a metal film resistive film. The resistance value between the ends is 1.5Ω, and a spiral cutout is formed on the circumferential surface of the resistor element at approximately the center, and the resistance value between both peripheral edges of the resistor element is 150Ω adjusted to the resistance value,
Applying an insulating resin paint to the peripheral surface of the resistor element,
A resistor element on which a protective film was formed by curing was prepared.

The weight of this resistor element was 3-14 mg. Furthermore,
Columnar iron media with a diameter of 1.0 mm and a length of 1 to 6 mm were prepared.

The weight of this media was 188 mg.Apart from these preparations, the electrolytic barrel plating equipment was not used.

A commercially available nickel electroplating bath (Watt bath) was filled in the plating tank of an electric barrel plating device.

The resistor element has a volume of 500 cc and the media has a volume of 2 n in a rotating barrel (volume 4 n ) of an electric barrel plating device.
00cc and rotated the barrel.

While rotating the barrel, connect 0.3A/2 between the cathode and anode.
A current of d m '' was continued to flow for 90 minutes to deposit a Ni plating film on the edges of both layers of the resistor element.

The deposited Ni plating film had an average thickness of 4.3 μm.

Furthermore, commercially available solder plating baths (phenol sulfonic acid bath,
After the Ni plating, electroplating was performed on the Ni plating film to form solder to a thickness of 3 μm.

Such a resistor element is screen printed with Ag-Pd conductive paste on an alumina substrate prepared in advance, solder paste is applied to the baked conductor land, the resistor element is placed on top of the solder paste, and reflow is performed. Then solder it.

In the direction perpendicular to the axial direction of the resistor element, J! The strength of the soldering was determined by pulling the tip of a push-pull gauge in a direction parallel to the surface of the i-board and reading the force when the resistor element peeled off from the board.

As a result of measuring the strength of 100 pieces of soldering, the value of the weakest one was 2.3 kg.

[Example 2] In Example 1, instead of the columnar iron media with a diameter of 1-0 mm and a length of 1.6 mm, electroless nickel was formed on the surface of alumina porcelain of the same shape and size. Do not make f into a conductor.
Example except that 3-2 mg of media was used.
As a result of performing the same procedure as in 1, the value of the weakest one is +2.0
It was kg.

[Example 31 In Example 1, instead of the columnar iron media with a diameter of 1-0 mm and a length of 1.6 mm, a lead media of the same shape and size with a weight of 25 mg Li was used. was carried out in the same manner as in Example-1, and the weakest value was: l
It was Ikg.

[Example-4] In Example-1, instead of the columnar iron media with a diameter of 1.0 mm and a length of 1.6 mm, a columnar iron media with a diameter of 0.8 mm and a length of (1.0 mm) was used.
The same procedure as in Example 1 was carried out except that 8 mm columnar lead media with a weight of 4 to 56 mg was used. As a result, the value of the weakest one was 2.0 kg.

[Example-5] In Example-1, instead of the columnar iron media with a diameter of 1.0 mm and a length of 1.6 mm, a media with a diameter of 1.0 mm and a length of 3 mm was used.
The results were obtained in the same manner as in Example-1, except that 8.1 mg of columnar iron media of 0 mm was used.
The value of the weakest one was 2-2Kg.

[Example-61 In Example-1, instead of the columnar iron media with a diameter of L Omm and a length of 1.6 mm, a columnar iron media with a diameter of 0.5 mm and a length of 1.0 mm was used.
The same procedure as in Example 1 was carried out except that a 6 mm columnar lead media with a weight of 3 to 56 mg was used. As a result, the value of the weakest one was 2.0 kg.

[Example-71 In Example-1, except that instead of the columnar iron media with a diameter of 1.0 mm and a length of 1.6 mm, spherical iron media with a diameter of 10 mm and a weight of 4.11 mg were used. As a result of carrying out the same procedure as in Example-1, the value of the weakest one is:
'It was 15 kg.

[Comparative Example-1] In Example-1, instead of the columnar iron media with a diameter of 1.0 mm and a length of 1.6 mm, a spherical alumina media with a diameter of 1.0 mm and a weight of 1 Omm and whose surface was made conductive with a nickel plating film was used. , Example-1 except that 1-Omg media was used.
As a result, the value of the weakest one was 1.0Kg.
Met.

[Comparative Example-2] In Example-1, instead of the columnar iron media with a diameter of 1.0 mm and a length of 1.6 mm, a media with a diameter of 1-0 mm and a length of 4-0 mm whose surface was made conductive with a nickel plating film was used. The procedure was carried out in the same manner as in Example 1 except that the media was made of columnar alumina and weighed 7.85 mg. As a result, the value of the weakest one was 1.1 kg.

[Comparative Example-31 In Example-1, instead of the columnar iron media with a diameter of 10 mm and a length of 1.6 mm, a plate-shaped alumina with a diameter of 110 mm and a length of 1.6 mm whose surface was made conductive with a nickel plating film was used. The results were obtained in the same manner as in Example 1, except that the media weighed 12-56 mg.
The value of the weakest one was 0.8Kg.

[Effects of the Invention] According to the present invention, it is possible to perform electrolytic plating using a rotating barrel on the terminal portion of a resistor using a film with a high resistance value without using a metal cap. There is no stretching, the plating film is deposited uniformly, and the solder plating applied on top of it is also deposited uniformly, providing strong soldering strength and a small, high-resistance resistor. The effect of being able to provide a highly reliable, small-sized, high-resistance resistor is significant.

Claims (1)

[Claims] A resistor element in which a resistive film is formed on the surface of an insulating carrier, a part of the film is covered with an insulating film, and the other part is used as a connection electrode, and a medium for assisting electrical connection of the object to be plated. is placed in a rotating barrel equipped with a cathode and immersed in a plating tank equipped with an anode, and while rotating the rotating barrel, a voltage is applied between the anode and the cathode, and the connected electrode portion of the resistor element is , in a method of electro-barrel plating a low-resistance metal, the weight (Wm) of the medium is greater than or equal to the weight (Ws) of the resistor element, and the thickness (Dm) is 1 of the thickness (Ds) of the resistor element. A method for manufacturing a film resistor, characterized in that the length (Lm) is at most twice the length (Ls) of the resistor element and at least the thickness (Dm) of the media.