JPH02244787A - Enamelled substrate of resistance circuit with insertion terminal - Google Patents

Abstract

PURPOSE:To eliminate the necessity of forming mating terminals in accordance with a distance from a heating part even if a plurality of resistance circuits are to be used in series connection by a method wherein conductor circuits having required lengths are connected to the resistance circuits. CONSTITUTION:An enamelled substrate 4 is a resistance circuit substrate and the whole substrate is composed of a resistance circuit 3. Conductor circuits 2 which are so formed as to be connected to the resistance circuit 3 are conductor circuits for overheat protection. The resistance circuit 2 is preferably made of conductor material whose surface resistivity is as low as possible. If the material having the surface resistivity not higher than 10mOMEGA/square is employed, the necessary length of the conductor circuit has to be varied in accordance with the surface resistivity of the resistor circuit and so forth and the length not less than 5mm is necessary.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a hollow resistance circuit board with an insertion terminal used for controlling the rotation speed of an indoor air conditioning fan in an automobile, and is particularly intended for preventing overheating of the insertion terminal fitting part. This invention relates to a resistor circuit enamel board with an insertion terminal.

[Conventional technology]

Enamel substrates are made by coating the surface of a metal core with enamel, firing it, and then forming conductor circuits and mounting components. A resistive circuit layer is provided on the surface of this enamel substrate (j
The resistor circuit board has excellent heat dissipation properties and high mechanical strength, so it has the advantage that it can be used in a thin plate shape by being attached to various things without special mechanical reinforcement.

One of the applications that utilizes the advantages of this enameled resistance circuit board is a sheet heating element.

The problem when using an enameled board as a surface heating element is that the entire board generates a large amount of heat, and the board has good thermal conductivity, so the terminal part that connects to the external power source becomes hot, and the terminal part becomes hot. This oxidation increases the contact resistance of the connection and reduces reliability.

Like this! In order to avoid the R state, the present applicant proposed in Utility Model Application Publication No. 59-161283 that the resistance circuit conductor is provided in a direction away from the heater part along the surface direction, that is, a distance from the heater part. The connection part of the board is formed so as to protrude in the direction of length, and a low resistance conductor circuit that does not generate heat from itself is connected to the resistance circuit conductor of the heater part, and this is extended to the connection terminal part. proposed to reduce the temperature rise in the terminal area.

[Problem to be solved by the invention]

However, these methods are effective for applications where there are few restrictions on the shape of the board or one method, such as sheet heating elements, but they are effective for applications that are mounted on various devices and used. It has been found that when used as a resistor circuit board, the entire board becomes large and the space factor deteriorates.

The present invention aims to reduce the temperature rise of the terminal portion that is fitted and inserted into the connector for connection with the outside in a circuit board used as a resistance circuit board for control of automobiles and the like that require such a space factor. The purpose of this invention is to provide a resistance circuit board that can control y/no.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventor conducted various studies on factors that contribute to the temperature rise of the fitting part of the insertion terminal in a resistance circuit enamel board with an insertion terminal.
In a board such as a control resistor circuit board where the entire circuit does not generate much IR heat, the temperature effect of the insertion terminal mating part due to heat transfer of the board is small and is hardly a problem; It was found that heat transfer from the circuit contributed to the temperature rise at the insertion terminal fitting part.

In other words, in a board that generates relatively little heat, such as a resistance circuit board for IIJID, the temperature rise at the fitting part of the insertion terminal that is inserted and fitted into the connection connector is more dependent on the distance from the resistance circuit part that generates heat. It was also found that the length of the conductor circuit formed by connecting to the resistor circuit was a major factor.

The present invention has been made based on such knowledge, and in a resistance circuit enamel board with insertion terminals having insertion terminals for fitting with an external connection connector, it is possible to continuously fit the insertion terminals into the fitting portions of the insertion terminals. A conductor circuit is connected to a resistor circuit to control the temperature rise of the mating part, and the length of this conductor circuit is appropriately selected to prevent overheating of the mating part of the insertion terminal. It is characterized by:

Here, the conductor circuit for preventing overheating of the insertion terminal mating part is laminated on a pre-formed resistance circuit, or a part of the resistor circuit that is entirely composed of a resistor circuit is used as a conductor circuit. The conductor circuit may be formed of a conductive circuit and arranged continuously in the fitting portion of each insertion terminal.

The present invention will be further explained in detail with reference to FIG.

This resistor circuit board shows the basic circuit of a resistor circuit enamel board used for the rotation speed υ1w of an automobile's indoor air conditioning fan.

1 is a fitting part when the board is inserted into the connector, 3 is a resistance circuit, and 4 is an enameled board. Reference numeral 2 denotes a conductor circuit for controlling the transmission of heat from the resistance circuit section 3 to the fitting section 1 with the connector and preventing the fitting section 1 from overheating.

It is desirable for this conductor circuit to have as small a sheet resistance value as possible, but it is usually 10 mΩ/['' or less. Area resistance value 10fT1Ω/□ for conductor circuit
The required length of the conductor circuit when the following is used varies depending on the area resistance value of the resistor circuit, etc., but it is usually necessary to form it to a length of at least 51M1. or,
When the sheet resistance value exceeds 10 mΩ/□, the difference between the sheet resistance value of the resistor circuit and the sheet resistance value of 20 to 100 mΩ/□ decreases, so the effect of controlling heat transfer to the mating part of the insertion terminal decreases, and the mating It is difficult to keep the joint temperature below the heat and humidity resistance of Plus Books used in the connector housing.

(Example) (Example 1) The enamel board 4 shown in FIG.

Resistance part 3 has a total resistance of 20, area resistance fa 45mΩ/□
This is an Aq-Pd based thick film circuit. The conductor circuit 2 formed by connecting to the resistance circuit 3 is the overheat prevention conductor circuit of the present invention.

Both the fitting part 1 with the connector and the conductor circuit 2 are 4mΩ.
/□ AQ thick film circuit is used.

Place this board in the ventilation section of a car interior ventilation fan (=
j' l-J, a current of 10Δ is passed through a metal terminal,
The maximum temperature of the board was 135℃ using a laser viewer.
The temperature of the connection terminal fitting part was measured when the temperature reached . The length of conductor circuit 2 is ■5#11■10m+, ■15m, ■2
Table 1 shows the temperature of the upper arm of the connecting terminal fitting part when the distance is changed to 0 m. As a comparative example, the temperature rise of the fitting part when the length of the conductor circuit 2 is 4.5M, and as a conventional example, the temperature rise of the fitting part when no conductor circuit is provided are shown as OI.

As is clear from the results in Table 1, the temperature rise at the fitting portion with the connector decreases as the length of the conductor circuit increases from 5 to 20B.

Therefore, it can be seen that in a resistance circuit such as the present invention, it is effective to form the conductive circuit well in lowering the temperature of the fitting portion.

On the other hand, in conventional circuit boards that do not have low resistance conductor circuits, the temperature at the fitting portion rises to 110 DEG C., making it impossible to use connectors made of ordinary plastic materials.

Further, as a comparative example, when the length of the conductor circuit was set to 4.5 am, the temperature increase was 60° C., which was the upper limit temperature for use of ordinary plastic connectors. Therefore, in practice, it is necessary to form it at least 5 am as in Example NQ1.

(Example 2) R1 (6a=6b), R2 (6a- 6d), R3(
6a-6c) were formed so that three types of resistor circuits could be selected.

Next, on the circuit of this resistor, a conductor circuit (2a, 2b, 2c) is formed continuously to the fitting part (1) of each insertion terminal using a low resistance conductor with a sheet resistance value of 10 mΩ/□.

A resistor circuit enamel substrate provided with 2(j) was manufactured.

As in Example 1, this board was attached to the ventilation part of the ventilation fan for the interior of a self-help vehicle, and currents of 8A, 6.5A, and 4A were applied to each resistor circuit R1°F and 4R3, respectively, and the R of the board was heated with thermopure. The temperature at the fitting part of each terminal was measured when the high temperature reached 157°C, and the effectiveness of overheat protection was investigated when the length of the conductor circuit was varied. These results are shown in Table 2.3.4.

As is clear from this, even when multiple resistors are connected in series, the temperature of the fitting part with the connector is
■By appropriately selecting the length of the conductor circuit continuous to the joint, the required overheat protection 11. This shows that it is effective.

Figure 3 shows how the resistor circuit board shown in Figure 2 is connected to the
FIG. 2 is an explanatory diagram showing a connection method.

R1=0.5Ω, R2=1.50, R3=3.50, FIG.

Claims (3)

[Claims] 1. In a resistor circuit enamel board having insertion terminals for mating with an external connection connector, a conductor circuit is laminated on the resistor circuit in succession to the fitting portion of each insertion terminal, and the length of this conductor circuit is A resistance circuit enameled board with an insertion terminal, characterized in that the insertion terminal fitting portion is configured to prevent overheating by appropriately selecting the insertion terminal fitting portion. 2. In a resistance circuit enamel board having insertion terminals for mating with an external connection connector, a part of the resistance circuit is formed by a conductor circuit, and this conductor circuit is continuously arranged in each insertion terminal fitting part. A resistor circuit enamel board with an insertion terminal characterized by: 3. The conductor circuit has a length of at least 5 mm,
The resistance circuit enamel substrate with insertion terminals according to claim 1 or 2, characterized in that the sheet resistance value is 10 mΩ/□ or less.