JPS6124225A - Method of producing jig for electronic part baking - 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 [Field of Industrial Application] The present invention relates to improvements in jigs used for firing electronic components, such as ceramic capacitors.

[Problem that the invention seeks to solve]

When manufacturing electronic components, such as ceramic capacitors, there is a process of firing the capacitor base at 1200 to 1400°C, but zirconia is used for the parts that come in contact with the capacitor as it is the material that least reacts with the capacitor. There is. In the past, during actual firing, a zirconia board was laid in an alumina-silica jig, specifically a sagger, and zirconia powder was placed on top of the zirconia plate, and the capacitor base was arranged, or a zirconia sagger was placed on top of the zirconia plate. A common method is to place zirconia powder on top of the capacitor base. However, although the former method of laying zirconia plates is relatively inexpensive, it is very complicated and time-consuming when loading and unloading products manually.
In addition, in the case of automation, when attempting to take out the product by inverting the sagger to take out the condenser, the zirconia plate falls off, creating a bottleneck in automation. On the other hand, the latter method in which the entire sagger is made of zirconia has the drawbacks that zirconia is susceptible to thermal shock due to rapid heating and cooling, has a high specific gravity (and is very expensive).

In order to eliminate the above-mentioned drawbacks, a method can be considered in which a widely used alumina-silica sagger is used and a zirconia sprayed layer is formed on the surface of the sagger on which the object to be fired is placed. However, if zirconia is simply sprayed onto an alumina-siliceous material, the sprayed layer will peel off from the base material as the thermal history of heating and cooling is repeated.

As is well known, zirconia has a monoclinic-tetragonal-cubic crystal transformation, and in the capacitor firing temperature range, it undergoes abnormal expansion and contraction due to crystal transformation. The thermal spray layer peels off due to volume changes. Abnormal expansion and contraction accompanying this crystal transformation can be prevented by using zirconia to which a stabilizer has been added (stabilized zirconia).

Calcium oxide, magnesium oxide, and yttrium oxide are known as stabilizers for stabilized zirconia, but magnesium oxide is unstable as a solid solution with zirconia, and MgO easily escapes from the solid solution during use at high temperatures. Dispersed yttrium is expensive. In comparison, calcium oxide has a stable solid solution, CaO is relatively difficult to diffuse even at high temperatures, and is inexpensive. Therefore, calcium oxide is preferred as a stabilizer.

However, when thermally spraying CaO-stabilized zirconia onto an alumina/siliceous base material, CaO gradually diffuses into the base material at high temperatures (therefore, the amount of CaO in the sprayed layer gradually decreases, and the zirconia stabilizes). When the area deviates from the area, abnormal expansion and contraction due to heating and cooling gradually appears, causing peeling.Therefore, anticipating the diffusion and disappearance of CaO, a large amount of CaO is removed.
When zirconia containing barium titanate is used, the reaction with barium titanate is accelerated during firing of an electronic component, for example, a capacitor mainly composed of barium titanate, which may adversely affect the characteristics of the capacitor.

[Means for solving problems]

The present inventors have conducted various studies on the problems of thermal expansion between the thermal sprayed layer and the base material and reaction between the thermal sprayed layer and the electronic components in a jig for firing electronic components manufactured by the above thermal spraying method. By adjusting the content of A1 and SiO3 in the stabilized zirconia and the content of other stabilizers in the stabilized zirconia, it is possible to make the thermal expansion curves of the base material and the sprayed layer almost equal, and also to almost eliminate the reaction. The present invention was completed by discovering that this is possible.

The present invention is a method of thermally spraying CaO-stabilized zirconia onto the surface of a fire-resistant base material, in which stabilized zirconia with a low CaO content in the thermal spraying material is gradually sprayed from the base material side toward the surface. The present invention provides a method for manufacturing a jig for firing electronic components.

As a result of studying the thermal expansion behavior of various refractory materials, the present inventors found that alumina-siliceous materials used for ordinary refractory bricks and saggers have high Alco03 content.
It was found that the thermal expansion curve was relatively similar to that of the CaO-stabilized zirconia sprayed layer in the area. It has also been found that when the CaO content in the stabilized zirconia is increased, the thermal expansion behavior can be followed by using an alumina-silica material with a high A1co03 content.

Therefore, A110385% by weight or more, SiO215% by weight
Hereinafter, if a material containing 6 to 15% by weight of CaO in stabilized zirconia is thermally sprayed using a fire-resistant base material with the remainder consisting of unavoidable impurities, it will peel off even after more than 20 thermal cycles. (It turns out that it can be used.

On the other hand, in order to eliminate the adverse effects on products due to reactions, the zirconia thermal spray material is first changed from a material with a high CaO content to a material with a low CaO content.
Finally, it has been found that the limit of the stabilization region, or even the partial stabilization region, can be addressed by spraying a material close to the stabilization region. This change in stabilizer in the thermal spray material may be gradual or continuous.

[Effect]

The fireproof base material is alumina-silica and contains 85% by weight of Al2O3.
In the above, S i 0215% by weight or less, with the remainder consisting of unavoidable impurities. If AI:LC is 1385% by weight or less and 5iO2 is 15% by weight or more, the base material cannot follow the thermal expansion behavior of stabilized zirconia.

The content of the stabilizer CaO in the stabilized zirconia in the portion directly in contact with the base material is in the range of 6 to 15% by weight. Ca
During use at high temperatures, O gradually diffuses into the base material and is lost, and its content gradually decreases. Therefore, in terms of stabilizing zirconia, the more stabilizer the better, but if it exceeds 15% by weight, Even if the amount of AI:103 in the alumina-silica base material is increased, peeling occurs and the sagger cannot withstand repeated use. On the other hand, if Ca06% by weight or less, stability is likely to be lost due to disappearance of CaO, which is also not preferable.

The CaO content of the stabilized zirconia sprayed on the outermost layer is 4 to 10% by weight. Even in the partially stabilized region, 4
If it is more than 4% by weight, the abnormal change in volume due to the phase change of zirconia is not so great, but if it is less than 4% by weight, it becomes severe and causes peeling. Moreover, if it exceeds 10% by weight, reaction with electronic components becomes a problem. There may be no intermediate layer other than the layer in contact with the base material and the outermost layer, but if the two layers have considerably different amounts of CaO, it is more preferable to provide an intermediate layer with an intermediate amount of CaO. Alternatively, it is more desirable to continuously change the amount of CaO in the zirconia sprayed layer in order to prevent separation between the sprayed layers.

[Structure of the invention]

Next, the manufacturing method of the present invention will be explained.

Considering the melting point of zirconia, plasma spraying is preferable, and water plasma spraying is particularly preferable. Thermal spraying is carried out by the usual ceramic spraying method, and the particle size of the sprayed material is 150 μm or less.

The relationship of the thermal expansion of the fireproof base material to the A1.03 and S i O2 content in the fireproof base material and the relationship of the thermal expansion of the stabilized zirconia sprayed layer to the CaO content are determined in advance, and the fireproof base material with a determined composition is determined. When using a stabilized zirconia, determine the CaO content of the stabilized zirconia that has the same thermal expansion behavior as the refractory base material, or conversely determine the CaO content of the stabilized zirconia
When the aO content is determined, the composition of the refractory substrate is determined which has the same thermal expansion behavior as the stabilized zirconia.

As mentioned above, the CaO content of stabilized zirconia is 6 to 1.
The range is 5% by weight.

The order of thermal spraying is to first coat the refractory base material with a CaO content of 6 to 5 and a thickness of 0.05 to 5 mm. After the thermal spraying is completed, stabilized zirconia with a CaO content of 4 to 10% by weight is again thermally sprayed. The thickness of the sprayed layer is still 0.05 to 5 mm.
shall be. In this way, the jig is manufactured.

The above is a case where there are two thermally sprayed layers, but when spraying onto the base material, the CaO content in the stabilized zirconia is changed to one that gradually decreases and is thermally sprayed one after another, and the outermost layer has a predetermined CaO content. By thermally spraying stabilized zirconia, the number of thermally sprayed layers can be increased to three or more, or it is also possible to thermally spray by continuously supplying stabilized zirconia with a gradually reduced CaO content from a hopper without interrupting thermal spraying. good.

By doing so, stability against thermal history is further increased than in the case of two sprayed layers.

〔Example〕

The method of the present invention will be explained in more detail with reference to Examples below.

Example I An alumina-silica refractory base material consisting of 92% by weight of AI:20a, 26% by weight of 5iO, the raffinate portion of which was made up of unavoidable impurities, was cut out to a size of 170xllOxlO mm, and stabilized zirconia powder containing 10% by weight of CaO was first applied to its surface. Thermal spraying was carried out to a thickness of 0.2++un using a water plasma sprayer. Next, stabilized zirconia powder with a CaO content of 5% by weight was sprayed using the same water plasma spraying equipment.
A sprayed body was obtained by spraying to a thickness of 3 mm.

Example 2 First, stabilized zirconia containing 10% by weight of Ca0, I
n+m, then 0.1 mm of stabilized zirconia containing 7% by weight of Ca'0, and finally 0.1 mm of stabilized zirconia containing 5% by weight of CaO was sprayed in the same manner as in Example 1) ! ! A product consisting of three layers was obtained.

Example 3 Two thermal spray powder supply tanks were prepared, and one tank was filled with C.
Stabilized zirconia with an aO content of 5% by weight and C
Add calcium zirconate with an aO content of 31% by weight,
The feeder was adjusted to mix the two so that the apparent CaO content of the mixture was continuously changed from 10% by weight to 5% by weight, and the mixture was supplied to a thermal spraying device.
A sprayed body was obtained by spraying onto the same refractory base material to a thickness of 0.5 mII using a water plasma spraying machine.

Comparative Example 1 A thermal spray body was obtained in the same manner as in Example 1 except that the thermal spray layer was a single layer of 0.5 mm thick stabilized zirconia powder with a CaO content of 5% by weight.

Comparative Example 2 A thermal spray body was obtained in the same manner as in Example 1, except that the thermal spray layer was a single layer of 0.5 mm thick stabilized zirconia powder with a CaO content of 12% by weight.

〔Effect of the invention〕

Barium titanate capacitor bodies were placed on the five samples of Examples 1 to 3 and Comparative Example 1.2, and the temperature was raised from room temperature to 1400"C at a heating rate of 5"C/min in an electric furnace.
The operation of furnace cooling at room temperature in the hr storage chamber was repeated to observe the adhesion between the base material and the sprayed layer and the effect on the characteristics of the capacitor. As a result, in the sample of Comparative Example 1, slight peeling was observed at the end of the '66th heat cycle, and approximately 1/3 of the sample was peeled off at the 9th heat cycle. In the sample of Comparative Example 2, no peeling was observed even after the 10th heat cycle, but the barium titanate capacitor contained CaO.
However, in Examples 1 to 3, the influence of the reaction with
In all of the samples, no influence of reaction with CaO was observed on the capacitors after firing, and some peeling was observed in the sample of Example 1 after the 15th heat cycle, but after the 15th heat cycle, the capacitors were used up to 20 cycles. did it. On the other hand, no peeling was observed in the samples of Examples 2 and 3 until the 20th test. This clearly shows the effect of the present invention.

As stated above. As such, the electronic component firing jig manufactured by the method of the present invention is made by thermally spraying CaO-stabilized zirconia whose thermal expansion matches that of the base material onto an alumina-silica refractory base material.
Furthermore, by thermally spraying stabilized zirconia with a reduced CaO content on the top layer, the zirconia will remain stable even when the jig is subjected to thermal history, without adversely affecting the electronic components of the fired object during use of the jig. The coating does not lose its properties and the sprayed layer does not peel off (and can be used repeatedly).

Claims (4)

[Claims] (1) Al_2O_385% by weight or more, SiO_215
A method of thermally spraying stabilized zirconia containing 4 to 15% by weight of CaO on the surface of a fire-resistant base material consisting of A method for manufacturing a jig for firing electronic parts, characterized by thermally spraying stabilized zirconia with a low CaO content. (2) Spraying stabilized zirconia with a CaO content of 6 to 15% by weight on the base material side, and then thermal spraying stabilized zirconia with a CaO content of 4 to 10% by weight on top of it. A method for manufacturing a jig for firing an electronic component according to claim (1). (3) Stabilized zirconia with a CaO content of 6 to 15% by weight is sprayed on the base material side, and stabilized zirconia with a CaO content of 4 to 10% by weight is sprayed on the surface side, and between both sprayed layers. Claims (1) are characterized in that one or more layers of stabilized zirconia with an intermediate CaO content are thermally sprayed.
) A method for manufacturing a jig for firing electronic components as described in (4) Stabilized zirconia with a CaO content of 6 to 15% by weight on the base material side and stabilized zirconia with a CaO content of 4 to 10% by weight on the surface side so that the CaO content changes continuously. A method for manufacturing an electronic component firing jig according to claim (1), which comprises thermal spraying.