JPH0514548Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hybrid integrated circuit board, and particularly to a hybrid integrated circuit board in which a film resistor is formed on an insulating substrate.

[Prior Art] Conventionally, in a hybrid integrated circuit board in which a circuit pattern and a film resistor are formed on an insulating substrate,
A circuit pattern and a film resistor are formed on the insulated circuit board by screen printing, etc., and the resistance value of the film resistor is adjusted by means such as laser trimming, and then components such as capacitors and transistors and leads are formed. The wires are soldered, and finally, to protect the circuit from external influences, the surface is coated with resin or the like to cover it.

In addition to applying a resin or the like as described above, there is already known a method for protecting the film resistor by attaching a protective cap to the insulating substrate so as to cover the film resistor.

[Problems to be solved by the invention] However, in the former conventional technology, after adjusting the resistance value of the film resistor, a resin etc. is applied to the surface of the film resistor, so the shrinkage that occurs when the resin hardens. As a result, stress is generated in the film resistor, resulting in distortion in the plane, and as a result, its resistance value changes. In addition, with subsequent temperature changes,
Due to the difference in coefficient of thermal expansion between the resin and the film resistor, thermal stress is generated in the film resistor, which also causes distortion in the plane, resulting in a change in its resistance value.

Therefore, the resistance value of the film resistor that has been painstakingly adjusted varies thereafter, making it impossible to obtain sufficiently high accuracy. Therefore, in the prior art, it is difficult to adjust the resistance value to an accuracy of ±0.5% or less.

Furthermore, in the case of the latter conventional technique using a protective cap, a separate step is required to attach the protective cap onto the insulating substrate. Therefore, the number of manufacturing steps for the circuit board increases, leading to an increase in the manufacturing cost of the circuit board due to the increase in the number of man-hours. Furthermore, since a space must be provided for installing a protective cap around the film resistor, there is an area around the film resistor where a circuit pattern cannot be formed. For this reason, circuits cannot be formed at high density on the insulated circuit board, which becomes an obstacle to increasing the density of circuit patterns.

Therefore, in view of the problems in the prior art described above, the present invention is capable of protecting the film resistor without increasing the manufacturing process of the circuit board and without becoming an obstacle to increasing the density of the circuit. The present invention aims to provide a hybrid integrated circuit board with a structure.

[Means for solving the problem] That is, the object of the present invention is to form a conductive pattern around the film resistor formed on a first insulating substrate, and to form a conductor pattern corresponding to the conductive pattern. A second insulating substrate on which a conductor pattern for soldering is formed on the lower surface is separated from the film resistor, and is mounted on the first insulating substrate straddling the film resistor. This is achieved by a hybrid integrated circuit board characterized in that a conductive pattern on an insulating substrate is soldered to a conductive pattern on a first insulating substrate.

[Function] According to the hybrid integrated circuit board, the film resistor that requires protection is protected from external influences by the second insulating substrate, and the second insulating substrate is Because it is separated from the shaped resistor, it is not subject to distortion due to thermal stress or the like. Therefore, the resistance value does not change, and the resistance value once adjusted can be stably maintained thereafter.

The second insulating board is mounted on the first insulating board and soldered onto the conductor pattern formed on the first insulating board, so other electronic components can be mounted and soldered. In the attaching process, it can be simultaneously mounted on the first insulating substrate and soldered. Therefore, a special step of mounting the second insulating substrate on the first insulating substrate is not required.

Furthermore, the second insulating substrate occupies a certain range of area on the first insulating substrate, but since this second insulating substrate is the same insulating substrate as the first insulating substrate, It can be used to form circuits. Therefore, a double circuit can be formed on the film resistor, and the density of the circuit can be increased.

[Examples] Examples of the present invention will be described below with reference to the drawings.

As shown in Figures 1 and 2, alumina (AI ₂
Conductive patterns 11, 12 and a film resistor 3 are formed in a predetermined shape by, for example, screen printing on the surface of a first insulating substrate 1 made of O ₃ ), etc., thereby forming a so-called hybrid integrated circuit board. It is configured. A part of the surface of the first insulating substrate 1 of such a hybrid integrated circuit board, for example, the surface on which the film resistor is formed (the first insulating substrate shown on the lower side in FIG. 1), another ceramic plate made of alumina or the like similarly to the first insulating substrate 1, that is, a second insulating substrate 2 for protection is provided to cover the film resistor 3. It is being

Regarding a part of the surface of the first insulating substrate 1 of the hybrid integrated circuit board as described above (the corner of the first insulating substrate 1 shown on the lower side in FIG. 1), FIGS. This will be explained in more detail. First, in FIG. 2, conductive patterns 11 and 12 are formed at the lower right corner of the first insulating substrate 1 by printing a conductive paste such as Ag-Pd paste, drying it, and baking it. There is. These conductor patterns 11,
Between 12 and 12, a resistance paste such as RuO ₂ is printed, dried, and fired to form a film resistor 3.
is formed.

Furthermore, in the figure, a so-called soldering pattern 1 for attaching the second insulating board 2 is shown.
3 and 14 are formed by printing, drying, and baking a conductive paste in the same way as the conductor patterns 11 and 12. These soldering patterns 13 and 14 can be formed simultaneously with the conductor patterns 11 and 12, and in this case, the conductor patterns can be extended and formed integrally with them.

Then, the hybrid integrated circuit board thus formed is processed such that the resistance value of the film resistor 3 is reduced to, for example, 3KΩ±0.05% by means such as a laser trimming method.
Adjusted with a degree of accuracy.

On the other hand, in order to sufficiently cover the parts such as the film resistor 3 that should be protected from external influences, other ceramic plates as shown in Fig. 3 are used for protection. A second insulating substrate 2 is prepared. As shown in the figure, Ag-Pd paste is printed on the four corners of the lower surface of the second insulating substrate 2 in the same manner as the conductor patterns 11 and 12, dried, and fired to solder. A pattern 21 for attachment is formed.

FIG. 4 shows a state in which the second protective insulating substrate 2 shown in FIG. 3 is attached on the surface of the hybrid integrated circuit board shown in FIG. 2. As is clear from this figure, the solder layer 4 is formed on the conductive patterns 11 and 12 formed on the surface of the first insulating substrate 1 and the soldering patterns 13 and 14, and It is soldered to a soldering pattern 21 on the lower surface of the second insulating substrate 2 . For forming this solder layer 4, for example, a reflow method or the like can be used.

Furthermore, a protective means such as a resin can be applied from above, and in this case, the resin does not adhere to the surface of the film resistor 3 due to the second protective insulating substrate 2.

Note that by forming a circuit using the front and back surfaces of the second insulating substrate 2, a higher density circuit can be constructed. That is, a circuit pattern is formed on the front and back surfaces of the second insulating substrate 2, and is then attached to the first insulating substrate 1 via the soldering pattern 21 and the soldering patterns 13 and 14.
It is connected to the conductor patterns 11 and 12 on the side.

As a result of actually measuring the resistance value of the film resistor 3 after completion of the hybrid integrated circuit manufactured in this way, the measured value was 3KΩ±0.07%, which shows that the drift is less than that of the conventional one. has been reduced. Furthermore, 100 cycles of heat cycle tests were conducted at -40°C for 30 minutes and at 125°C for 30 minutes, and the resistance value of the film resistor 3 of the hybrid integrated circuit according to the present invention was
Almost no change was observed at 3KΩ±0.08%.
On the other hand, in the case where the surface of the first insulating substrate 1 including the circuit pattern on the surface is covered with epoxy resin as in the conventional example described above, the resistance value of the film resistor after trimming is Even though the resistance was 3KΩ±0.05%, after painting the accuracy decreased to 3KΩ±0.40%. Also, after performing the heat cycle test mentioned above for 100 cycles, the resistance value
The accuracy decreased even more to 3KΩ±0.60%.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to prevent the accuracy of the resistance value from decreasing after adjusting the film resistor. Furthermore, since the second insulating substrate can be mounted and soldered together with other electronic components on the first insulating substrate, there is no need to add a separate process for attaching the second insulating substrate. Therefore, the manufacturing cost of the hybrid integrated circuit board does not increase significantly. Furthermore, since a double circuit can be formed on the film resistor by using the second insulating substrate, it is possible to increase the density of the circuit.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing the hybrid integrated circuit board of the present invention, FIG. 2 is a partial plan view showing the configuration of the board of the hybrid integrated circuit board, and FIG. 3 is a protection screen for the hybrid integrated circuit board. Bottom view showing the board, Figure 4 is the first
It is a partial sectional view showing the AA cross section of the figure. DESCRIPTION OF SYMBOLS 1... First insulating board, 11, 12... Conductor pattern, 13, 14... Soldering pattern, 2
...Second insulating substrate, 21...Soldering pattern for second insulating substrate, 3...Film resistor, 4...
solder layer.

Claims (1)

[Utility Model Claims] (1) A hybrid integrated circuit board formed by forming a circuit pattern and a film resistor on an insulating substrate, characterized in that a conductor pattern is formed around the film resistor formed on a first insulating substrate, a second insulating substrate having a conductor pattern for soldering formed on its underside corresponding to the conductor pattern is separated from the film resistor and mounted on the first insulating substrate across the film resistor, and the conductor pattern of the second insulating substrate is soldered to the conductor pattern on the first insulating substrate. (2) A hybrid integrated circuit board according to claim 1, characterized in that a circuit is also formed on the surface of the insulating substrate.