JPS6062190A - Thin film printed board - 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] [Technical Field of the Invention] The present invention relates to a thick film printed substrate for hybrid IC,
In particular, the present invention relates to an insulating layer used to improve the position of components soldered onto a conductor pattern.

[Technical background of the invention]

When soldering electronic components such as capacitors, or mechanical components such as leads, on 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 be soldered. The expansion moves due to 9, making it difficult to fix it at the desired position. Conventionally, as a countermeasure, an insulating layer of glass or epoxy resin is printed in advance on a part of the conductor pattern or in the vicinity of the conductor pattern so as to surround the position where the component is fixed, thereby preventing the component from moving. things are being done. This makes it possible to perform two soldering operations at desired positions with high precision and high reproducibility. Figures 1 and 2 show the specific configuration 2.
It shows. 1. In the same figure, 1rs,
A ceramic substrate is used, and a conductive pattern 2 is formed on the ceramic substrate 1. A linear insulating layer 3 is placed near the location where the O conductor pattern 2 components are soldered.
Alternatively, the frame-shaped insulating layer 4 is formed by printing. Then, a welding electrode 5, a bonding electrode 6, and a semiconductor pellet 7 are soldered 8 onto this ceramic substrate 1. When soldering is performed in this manner, the insulating layers 3 and 4 prevent the solder 8 from spreading 9, thereby improving the positional accuracy of the parts.

[Problems with background technology]

However, in such a conventional method, as a result of preventing the spread 9 of the solder 8, the skirting angle (fillet angle) θ of the solder 8 becomes large, as shown in FIG.

When such a thick film printed circuit board with a large skirting angle is subjected to a thermal shock test, for example, when the temperature condition is alternately changed from low temperature (-40℃) to high temperature (150℃), the ceramic substrate 1 and the solder Distortion occurs due to the difference in thermal expansion coefficient between
As shown in FIG. 4, cracks 9 occur in the conductor pattern 2 under the interface between the insulation 1@i3 and the solder 8. When the crack 9 occurs in this manner, the resistance value of the conductor pattern 2 increases, and if the crank advances 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 same figure, al”l:
When the skirting angle is large, b indicates the case where the skirting angle is small, and the crack occurrence rate is lower in the latter than in the former.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a thick film printed circuit board that has a small hem angle of solder, can reduce the occurrence of cracks in the conductor pattern, and can prevent the occurrence of disconnections, etc. It is in.

[Summary of the invention]

The present invention includes a substrate, a conductor pattern formed on the substrate, and an insulating layer formed so as to traverse the conductor pattern in the vicinity of a component to be soldered onto the conductor pattern. In the thick film printed circuit board, the insulating layer is provided with a gap that crosses the insulating layer, and a part of the solder escapes from this gap, thereby reducing the hem angle of 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 with a low resistance (1Ω or less). In the figure, No. 1 is a ceramic substrate, and a conductor pattern 12 made of a thick film of AgP'd is formed on this ceramic substrate 11. In the vicinity of the parts of this conductor pattern 12 where the parts are soldered,
For example, it is made of glass, and linear insulating layers 13, 13 that cross the conductor pattern 12 and a frame-shaped insulating layer 14 are printed, respectively. These insulating layers 13, 13.14
There are a plurality of gaps 15 each crossing the insulating layer.
゜15... is provided. Thus, welding electrodes 16, 16, bonding electrodes 17, and semiconductor pellets 18 are placed at predetermined positions on conductor pattern 12 with solder 19.
It is attached. The bonding electrode 17 and the electrode of the semiconductor pellet 18 are connected by a bonding wire 2o.

In the above-mentioned thick film printed circuit board, when attaching the parts of the welding electrode 16 and the bonding electrode 17 in half LU, the insulating layer 1
3.14 prevents most of the p-half 1:I-119 from expanding, so parts can be accurately fixed at desired positions as in the past. Further, a portion of this solder 19 flows into each gap 15 of the insulating layer 13.14. As a result, the skirting angle of the solder 19 is significantly smaller than that of conventional thick film printed circuit boards. Therefore, the occurrence of cracks in the conductor pattern 12 under the interface between the insulating layer 13, 14 and the solder 19 is reduced, thereby making it possible to prevent changes in the resistance value of the conductor pattern 12, and also to prevent wire breakage, etc. Accidents can be prevented. Figure 8 shows the thermal shock test (-40°C, 30°C).
The state of change in component quantity conductor resistance over time (←→150° C., 30 minutes) is shown by comparing the thick film printed circuit board 1j of the conventional example and the present invention. In the same figure, C is for the conventional example;
d shows the cases of the present invention, and at the time of 1000 cycles, the change in resistance change rate in the former increases by about 3%, while in the latter it increases by just under 1%, which is much smaller. .

In the above embodiment, the case where the gap 15 is provided in the insulating layers 13 and 14 for improving the positional accuracy of the parts to be soldered has been described. Capacitor 21 as shown in
It may also be provided in the insulating layer 23 provided between the welding electrode 22 and the welding electrode 22, and in this case as well, the same effect as in the above-mentioned implementation IZIJ can be obtained.

The width and number of the above-mentioned gaps are arbitrary, but when the width of the conductor pattern is narrow, the total convergence of the gaps is 30 to 7 times the width of the conductor.
Approximately 0% is desirable.

〔Effect of the invention〕

As described above, according to the present invention, in a thick film printed circuit board that has an insulating layer that crosses a conductor pattern near the components to be soldered, the hem angle of the solder can be adjusted without reducing the positional accuracy of the components. Can be made smaller. 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]

Figure 1 is a plan view showing the structure of a conventional thick film printed circuit board;
The figure is a cross-sectional view of the WT taken along the line A-A' in Figure 1, Figure 3 is an enlarged cross-sectional view of the main part of Figure 2, and Figure 4 is the occurrence of cracks in the conductor pattern and thermal shock. 6 is a plan view showing the structure of a thick film printed circuit board according to an embodiment of the present invention, and FIG. 7 is a cross section taken along line BB' in FIG. 6. Figures 8 and 8 are diagrams comparing the state of change in the rate of change in resistance with respect to thermal shock cycles between the conventional and the present invention, and Figure 9 is a plan view of another embodiment of the present invention. 11...Ceramic substrate, 12...4 body pattern,
13.14... Insulating layer, 15 Gap, 16... Welding electrode, 17... Bonding polarization, 18... Semiconductor pellet. Applicant's agent Suzue Takehiko Figure 1 Figure 3 q ＼ Figure 4 Number of thermal shock cycles 486 Figure

Claims (1)

[Claims] A substrate, a conductive pattern formed on the substrate, and an insulating layer formed across the conductive pattern in the vicinity of a component to be soldered onto the conductive pattern. A thick film printed circuit board characterized in that at least one gap is provided in the insulation layer.