JPH0526360B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a thick film printed circuit board for a hybrid IC, and in particular to an insulating layer used to improve the positional accuracy of components soldered onto a conductor pattern. Regarding.

[Technical background of the invention]

When soldering electronic components such as capacitors or mechanical components such as leads onto the conductor pattern of a thick film printed circuit board, when soldering to a conductor pattern that is wider than the width of the component, the component may move due to the spread of the solder. This makes it difficult to fix it in the desired position. Conventionally, as a countermeasure, it has been possible to prevent the movement of parts by printing an insulating layer such as glass or epoxy resin on a part of the conductor pattern or in the vicinity of the conductor pattern so as to surround the position where the part is fixed. It is being done. This results in
It is possible to perform soldering at a desired position with high precision and high reproducibility. FIG. 1 and FIG. 2 show the specific configuration thereof. That is, in the figure, 1 is a ceramic substrate, and a conductor pattern 2 is formed on this ceramic substrate 1. A linear insulating layer 3,
Alternatively, the frame-shaped insulating layer 4 is formed by printing.
Then, on this ceramic substrate 1, a welding electrode 5,
Bonding electrode 6 and semiconductor pellet 7 are soldered 8. When soldering is performed in this manner, the insulating layers 3 and 4 prevent the solder 8 from spreading, improving the positional accuracy of the components.

[Problems with background technology]

However, in such a conventional method, as a result of preventing the solder 8 from spreading, the fillet angle θ of the solder 8 becomes large, as shown in FIG. When performing a thermal shock test on such a thick film printed circuit board with a large hem angle, for example, when the temperature conditions were alternately changed from low temperature (-40℃) to high temperature (150℃), the ceramic substrate 1 and solder 8
Distortion occurs due to the difference in coefficient of thermal expansion between the insulating layer 3 and the solder 8, and as shown in FIG. When the crack 9 occurs in this manner, the resistance value of the conductor pattern 2 increases, and if the crack progresses further, the conductor pattern 2 may become disconnected. FIG. 5 shows the occurrence of cracks due to the skirting angle and thermal shock cycle. In the figure, a shows a case where the hemline angle is large, and b shows a case where the hemline angle is small, and the crack occurrence rate is lower in the latter case than in the former case.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to reduce the hem angle of the solder, reduce the occurrence of cracks in the conductor pattern, and prevent the occurrence of fluctuations in the resistance value of the conductor pattern and the occurrence of wire breaks. The purpose of the present invention is to provide a thick film printed substrate.

[Summary of the invention]

The present invention provides thick film printing comprising a substrate, a conductor pattern having a resistance value formed on the substrate, and a first electrode and a second electrode soldered to the conductor pattern in a spaced manner. In the substrate, first and second insulating layers are provided near the first and second electrodes so as to cross over the conductor pattern, and each of the first and second insulating layers includes:
The present invention is characterized in that a plurality of gaps having a width that can be closed by drawing the hem of the solder is provided, and a conductor pattern between the first and second electrodes is used as a conductor resistance.

According to the thick-film printing board having the above structure, a part of the solder can be drawn and released from the gap provided in the insulating layer, and the angle of the solder in this part can be made small. This reduces the occurrence of cracks in the underlying conductor pattern.

In addition, by providing multiple spaces between the above,
Multiple locations where cracks are difficult to form can be provided in the conductor pattern. Therefore, even if a crack occurs in the conductor pattern near the insulating layer, the conduction between the first electrode and the second electrode and the conductor pattern is maintained.
It is maintained, so to speak, by resistors connected in parallel. Therefore, fluctuations in the resistance value of the conductor pattern connecting the first and second electrodes can be reduced. Further, even if a crack occurs in one of the difficult-to-reach locations, the other locations remain conductive, thereby extending the life of the device.

Furthermore, by using the conductor pattern between the first and second electrodes as a conductor resistance, it is possible to reduce the number of parts constituting the circuit and to obtain a resistor with a minimum resistance value. Furthermore, since the gap has a width that is covered by the solder, it is possible to prevent the solder from flowing out from the gap, and also to prevent variations in the resistance value of the conductor resistor due to the solder.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows an example in which the present invention is applied to a thick film printed board using a conductor resistor that requires low resistance (1Ω or less). In the same figure, 11
is a ceramic substrate, and this ceramic substrate 1
A conductor pattern 12 made of a thick film of AgPd is formed on the conductor pattern 1 . This conductor pattern 1
In the vicinity of the location where the second component is soldered, linear insulating layers 13, 13 and a frame-shaped insulating layer 14 made of, for example, glass and crossing the conductor pattern 12 are printed. These insulating layers 1
3, 13, 14 are provided with a plurality of gaps 15, 15, . . . that cross the insulating layer, respectively. Therefore, at predetermined positions on the conductor pattern 12, welding electrodes 16, 16, bonding electrodes 1
7 and semiconductor pellets 18 are soldered 19. Bonding electrode 17 and semiconductor pellet 1
A bonding wire 20 is used to connect the electrode 8 to the electrode 8 .

In the above-mentioned thick film printed circuit board, when soldering the welding electrode 16 and bonding electrode 17, most of the solder 19 is prevented from spreading by the insulating layers 13 and 14. It can be fixed in position with high precision. Further, a part of this solder 19 is insulating layers 13 and 14.
Flows into 15 parts between each time. As a result, Handa 19
The skirting angle is significantly smaller than that of conventional thick-film printed circuit boards. Therefore, the occurrence of cracks in the conductive pattern 12 under the interface between the insulating layers 13 and 14 and the solder 19 is reduced, and as a result, the occurrence of cracks in the conductive pattern 12 is reduced.
It is possible to prevent changes in the resistance value of the wire, and also prevent accidents such as wire breakage. Figure 8 shows the changes in conductor resistance between parts during a thermal shock test (-40°C, 30 minutes ← → 150°C, 30 minutes), comparing thick film printed circuit boards of the conventional example and the present invention. It is. In the figure, c indicates the conventional example, and d indicates the present invention. At 1000 cycles, the change in resistance change rate for the former is approximately 3% increase, while for the latter. This will be a significantly smaller increase of just under 1%.

In the above embodiment, the gap 15 is replaced by the insulating layer 1 for improving the positional accuracy of the parts to be soldered.
3 and 14, but it may also be provided on an insulating layer for partitioning adjacent parts, for example, an insulating layer 23 provided between a capacitor 21 and a welding electrode 22 as shown in FIG. In this case as well, the same effect as in the above embodiment can be obtained.

The width and number of the gaps are arbitrary, but when the width of the conductor pattern is narrow, it is desirable that the total width of the gaps is about 30 to 70% of the conductor width.

〔Effect of the invention〕

As described above, according to the present invention, in a thick film printed circuit board having an insulating layer that crosses a conductor pattern near the components to be soldered, the hem angle of the solder can be reduced without reducing the positional accuracy of the components. can do. Therefore, it is possible to prevent the occurrence of cracks in the conductor pattern, reduce changes in conductor resistance, and significantly improve reliability.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the structure of a conventional thick film printed circuit board, Fig. 2 is a cross-sectional view taken along line A-A' in Fig. 1,
Figure 3 is an enlarged cross-sectional view of the main part of Figure 2, Figure 4 is a cross-sectional view showing how cracks occur in the conductor pattern, and Figure 5 shows cracks caused by the solder skirting angle and thermal shock cycle. Diagram showing the occurrence situation, Part 6
The figure is a plan view showing the structure of a thick film printed circuit board according to an embodiment of the present invention, FIG. 7 is a sectional view taken along line B-B' in FIG. 6, and FIG. 8 is a change in resistance against thermal shock cycles. FIG. 9 is a diagram illustrating a comparison between the conventional method and the present invention in terms of rate change, and FIG. 9 is a plan view according to another embodiment of the present invention. 11... Ceramic substrate, 12... Conductor pattern, 13, 14... Insulating layer, 15... Interval, 16
... Welding electrode, 17 ... Bonding electrode, 18
...Semiconductor pellets.

Claims (1)

[Claims] 1. A substrate, a conductor pattern having a resistance value formed on this substrate, a first electrode and a second electrode soldered to the conductor pattern in a spaced manner, and these first and second electrodes. first and second conductor patterns formed to cross over the conductor pattern in the vicinity of
an insulating layer, and each of the first and second insulating layers is provided with a plurality of gaps having a width such that the solder can be closed by pulling the hem thereof, and a gap between the first and second electrodes is provided. A thick film printed circuit board characterized by using a conductive pattern as a conductive resistor.