JPH0212439B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming electrodes on a piezoelectric plate used in an electronic scanning ultrasound probe of an ultrasound diagnostic apparatus. Conventionally, piezoelectric ceramics have been used as piezoelectric plates for ultrasonic probes, and wraparound electrodes as shown in FIG. 1 are formed. In addition,
In FIG. 1, 11 is a piezoelectric body, and 12 and 13 are electrodes. When such a piezoelectric vibrator is used in an electronic scanning probe, it is bonded to a backing material made of hard rubber or the like and cut into thin strips. Further, as shown in FIG. 2, lead wires are soldered to the wrap-around electrode portions of each strip. At that time, accidents such as the electrode material being eaten by the solder often occur. In addition, in FIG. 2, 21 is a packing material, 22 is a rectangular vibrator, and 23 is a lead wire.

Therefore, an object of the present invention is to provide an electrode forming method that prevents this accident and improves the yield in the device manufacturing process.

Usually, these electrodes are formed by applying silver paste or the like by screen printing and sintering it. At this time, the problem was how to form the wrap-around electrode part, such as making the screen pattern slightly larger than the piezoelectric plate so that the electrode material wraps around the side of the plate during printing, or) forming the electrode material on the side surface after double-sided printing. Efforts have been made, such as brush-painting. However, even if the electrode material is applied in this manner, when looking at the edges of the piezoelectric plate after sintering, the electrode film thickness is thinner than other parts. This is thought to be the cause of the solder bite accident at the edge of the wrap-around electrode.

Therefore, when the edges of the piezoelectric plate were chamfered so that the electrode material was applied thickly to the edge of the piezoelectric plate during printing, and the electrode was formed using the above process, a wrap-around electrode with sufficient thickness was obtained even at the edge. . As a result, the yield in the device manufacturing process was significantly improved.

The present invention will be explained in detail below with reference to Examples.
PZT ceramics made using the normal firing method.
It was cut into a shape of 74mm ^L x 12mm ^W x 1mm ^T and polished to a thickness of 0.35mm. This is a piezoelectric plate for an ultrasonic probe driven at a frequency of 5MHz, and 50 pieces were made per lot. Of these, 30 sheets were divided into two groups of 15 sheets each and the edges were chamfered. The degree of chamfering is shown in Figure 3. That is, FIG. 3A shows the case of 30 μm, and FIG. 3B shows the case of 50 μm.

Silver electrodes were baked onto the 50 piezoelectric plates created in this way using the same process of screen printing and brush painting on the edges. These were adhered to packing material using epoxy resin, and cut into strips with a 0.28 mm pinch using a 30 μm thick diamond blade.
Furthermore, a set of three strips was used to attach lead wires to the wrap-around electrode section by soldering, and then it was examined whether the piezoelectric body vibrated normally in each channel. Channels that did not vibrate normally were judged to have lost continuity due to solder erosion, and the yields were averaged and compared for all the boards with and without chamfering. The results are shown in the table of FIG.

There are two types of chamfering degrees, but first, if you compare the average of those without chamfering and those with chamfering, the yield has increased dramatically from about 85% to about 98%. Furthermore, for products with large chamfers, there are almost no accidents during the lead wire attaching process at 99.5%.

As explained above, when forming wraparound electrodes on a piezoelectric plate used in an electronic scanning ultrasound probe of an ultrasound diagnostic device, by chamfering the edges of the piezoelectric plate, the yield rate in the lead wire attachment process can be improved. It is clear that the results are significantly improved.

[Brief explanation of drawings]

Figure 1 shows the electrode structure of a piezoelectric vibrator for an electronic scanning ultrasound probe, Figure 2 shows the structure of an electronic scanning ultrasound probe, and Figure 3 shows the piezoelectric Cross-sectional view showing the degree of chamfering of the edge of the plate, No. 4
The figure is a diagram showing a table explaining the effects of the present invention.

Claims (1)

[Claims] 1. The wrap-around electrode of the piezoelectric plate of an electronic scanning ultrasonic probe that is used by cutting a piezoelectric vibrator into a large number of long and thin strip-shaped elements and forming an array is chamfered on the edge of the piezoelectric plate, and then the electrode material is A method of forming electrodes by coating both sides and sides of a piezoelectric plate, including the chamfered portions.