DE2916016A1 - Hermetically sealed ceramic metal composite - useful as housing for electronic components has several soldered joints - Google Patents

Abstract

Hermetically sealed ceramic metal composite with high strength has the metal (alloy) and ceramic (Al2O3) parts bonded by butt soldering. Several soldered joints, behind one another, are provided on flanges of the hollow metal profile, open on one side, to the corresp. points on the metallised ceramic part. The composites are useful as housings for high power transmission tubes, vacuum switches and vacuum capacitors. The stress between ceramic and metal is reduced and the strength of the bond increased, whilst it is unnecessary to match the coeffts. of expansion of the material used exactly.

Description

Hermetically sealed ceramic-metal connection

The invention relates to a hermetically sealed ceramic-metal connection with high strength, in particular ring-shaped parts made of metal and ceramics, preferably aluminum oxide, connected by butt soldering, in which the relevant Ceramic surfaces are metallized in the usual way and by an inserted solder, in particular hard solder, with the metal part in question by heating in a protective gas atmosphere or assembled in a vacuum; Such a ceramic-metal connection technique proves to be favorable for housings of high-power transmission tubes, vacuum circuit breakers and vacuum capacitors, which place high demands on their operational reliability will.

For electronic components of this type, a hermetic and a high strength bond between ceramic and metal or a further metallized ceramic part required. Also occur during operation such electronic components increased temperatures to the lead to high mechanical stresses between the ceramic and the metal.

Due to the fact that the metals used make one strong have different expansion coefficients to the ceramic, z. B. when soldering or at high application temperatures solder joint breaks.

This problem has so far been solved by using materials as possible same or adapted expansion coefficient for the metal partner to be soldered and the associated ceramic-metal parts was chosen as well as by suitable constructive measures for the soldering gap, which naturally only eilleu iögliciist may have a small diameter. Although these two connection techniques is satisfactory for many purposes, there is still inducement for others To look for ways to connect metals and non-metals, as flan strive is to improve the connection with regard to Lekagen and the @hermal Belas to increase feasibility.

In order to reduce this tension, one uses the technique of the stump or flat soldering like sio, for example iii of DE-PS 10 45 305 and in DE-OS 20 24 625 is described in more detail. It is between the metal and d e to the ceramic surface a metallic, preferably foil-like intermediate layer soldered in, whose expansion properties lie between the ceramic and the metal part. By the radial deformability of the thin intermediate layer will be the stresses that occur reduced. It also adjusts the expansion coefficients Middle piece. With such connections, however, breaks often occur in the ceramic on, which can be attributed to thermal stresses, as in particular those mentioned Expansion differences from the metal over the soldering point on the ceramics be transmitted. At higher application temperatures there is a risk of Ceramic-metal housings leak, which can lead to significant operational disruptions can. Therefore, possible solutions are sought, the security of such to further increase electronic components.

Another possibility through suitable constructive measures the junction between ceramic and metal the problem of different To circumvent expansion coefficients of the materials used, is in the DE-OS 23 26 373 proposed. The stresses when soldering metal parts in recesses ceramic bodies should be avoided by using the ceramic is only metallized in strips. Such technical measures described but are only applicable to a limited extent, e.g. B. from soldering ceramic tubes into one metallic block. Practice also shows that the solder joint does not expand at will because otherwise a tight seal is no longer guaranteed.

The object of the invention in view of this prior art It is important to further improve this tension gradient between ceramic and metal and to eliminate the above-mentioned disadvantages. The invention also draws a llermetic Sealing against a gas atmosphere. Furthermore, the strength of the composite should between ceramic nlld metal can be increased, but one no longer attains an exact one Adjustment of the expansion coefficient of the materials used is dependent.

The aforementioned object is achieved in that one behind the other Multiple soldering on the webs of one-sided open, profile-like Metal hollow bodies made at the connection point to the metallized ceramic part are.

There is an expedient further development of the inventive concept also in the fact that the hollow metal body has a U-shaped or comb-like cross section having.

An advantageous embodiment of the invention also consists in that the wall thickness of the webs to the height of the hollow body in a ratio of 1: 5 stands. The distance between the webs is also to be chosen so: i that it is 3 to 4 times the Web thickness is.

Embodiments of the invention are described below on the basis of Beschriben schematic drawings with further details. It shows Fig. 1: a cross section through a vacuum-tight vessel, e.g. B. a vacuum circuit breaker; 2: a cross section through a high-frequency support; Fig. 3: the cross section a high-performance transmitter tube.

The invention enables a bonded ceramic-metal solder connection, especially in the production of electronic housings. However, she is also in connection with the manufacture of various other composite articles with ceramic-metal structure of use. It can be assumed that metal and ceramics have different expansion coefficients that lead to high stresses in one Lead composite article of the type shown in Figs. 1 to 3, especially if the Object is heated. In order to reduce the mechanical stresses that arise, one uses as a constructive measure the stump or

the single face soldering. In this known measure are predominantly cylindrically shaped metal parts, the wall thickness of which is kept particularly thin, z. B. placed between 0.3 to 1 mm perpendicular to the metallized ceramic surfaces and soldered vacuum-tight over a relatively small cross-section. By the relative thin cylinder parts of the metal, the thermal stresses that occur are reduced. This technology can be used in terms of mechanical strength and operational safety of vacuum-tight ceramic} Ietall connections improve by the invention Multiple cutting edge soldering makes. This technical measure also increases at every connection point the thermal load capacity, even if there is a leak a soldering point does not affect the vacuum tightness of the vessel. Particularly brazing under protective gas above 800 ° C is based on this connection technology better and also enables the use of less qualified workers.

With ceramic material is in slels the present description the entire Plenty of those materials addressed that are used as insulating materials in electronics be used. In particular, it is those materials that are used in vacuum technology can be used, e.g. B. aluminum oxide in various degrees of purity, beryllium oxide, Zirconium oxide, sapphire and forsterite.

The choice of metals generally depends entirely on that intended Use of the item. It can be pure metal, such as B. molybdenum, Niobium, tungsten, copper or metal alloys made from one or more metals act, such as iron-nickel alloys and iron-nickel-cobalt compounds and nickel-chromium alloys. The choice of metals or metal alloys depends but does not depend on the fact that the expansion coefficient of the metals is as similar as possible should be the ceramic material. In addition to copper / silver / gold, the scope of the invention and their alloys can also be used with other solders, such as low melting brazing alloys for high frequency supporters.

Suitable solders in this regard are also palladium-nickel or solder pastes.

In the production of vacuum-tight metal-ceramic soldered joints usually the surface to be soldered of the ceramic 1 with a suitable, preferably Burned-in metallization layer 2, on which the metal hollow body 3 is soldered by means of soft or hard solder 5. Hard solders are for example can be used wherever the connection has a high mechanical strength Will demand strength and thermal resilience. Dic metallization of the ceramic 1 is usually carried out according to the molybdenum-manganese process by applying a Metal paste burned onto the ceramic in a controlled protective gas atmosphere or vacuum will. It can also be useful to have a ceramic part metallized in this way 2 to be nickel-plated so that later this part is well wetted by the solder.

Some exemplary embodiments are provided to further explain the present invention cited.

Example 1: The illustrated embodiment according to FIG. 1 shows a vacuum-tight vessel, as is an example of vacuum switches and vacuum capacitors is needed. In addition to a high strength of the ceramic-metal connection is still A vacuum density is required even after temperature cycles of up to 700 ° C. The ceramic 1 consists of aluminum oxide and is in a known manner on the end faces with a Brazed metallization layer 2 provided on which the hollow metal body 3 with the webs 6 is soldered several times on both sides. Alternatively, it is a U-shaped one Cross section 3a and a comb-like profile 3b shown. The soldering of another annular metallic Part 4 takes place according to the well-known single-blade soldering.

Example 2: In Fig. 2, a high-frequency support is shown, such as he z. B. can be used as an insulator in capacitively heated veneer presses. The ceramic 1 consists of glazed aluminum oxide and carries on both ends a brazeable metallization layer 2. The hollow metal body 3 with the coaxial Web 6 is in the soldering process with the ceramic 1 and the metal part 4 in the form of a Threaded socket connected by the solder 5. The soldering takes place at 780 ° C with a Alloy of 72 Ag / 28 Cu or other silver-copper solders at working temperatures from 600 ° C. The hollow metal body 3 in this case has a U-shaped profile a web thickness of 0.5 mm, the ratio of wall thickness to height 1: 5 amounts to.

The distance between the webs in this double-shoe soldering is 3 to 4 times the web thickness, which is a favorable training for the stress reduction the solder fillet is obtained.

Due to the double-cutting edge soldering according to the invention, this Post insulator the tensile load from 800 daN to 1250 daN after annealing treatment 500 ° C under protective gas.

In this version, the connection is only released at 1250 daN on the inner shoe and despite the deformation of the U-shaped metal body 3 the outer junction was still valmvm-tight. Also a subsequent temperature change test between 120 ° C and room temperature there was no deterioration in the values; even This time the solder joints remained vacuum-tight.

Example 3: A high power transmission tube is shown in FIG.

The structure consists of three tubular ceramic parts 1, namely made of aluminum oxide / ceramilc, the end faces of which in turn have a brazeable metallization layer 2 are provided. On each of these metallization layers 2 there is an annular one 1 mm high metal hollow body 3 is soldered to a U-shaped profile 3a. The web thickness is 0.3 mm. On this hollow metal body 3 are again metal parts 4 soldered on with a thickness between 0.5 and 2 mm. These can be used in assembly aid Metal hollow body 3 and the metal parts 4 or 7 by spot welding and an interposition stapled on a soldering foil beforehand.

In the practical execution for the production of more adhesive and Vacuum-tight Keramils metal soldered connections by double or multiple cutting edge soldering it is shown that connections with hollow strength and vacuum tightness can be made despite significant deviations in the expansion coefficient fully ceramic and Metal is preserved. Greasy cutting through the multiple cutting edges is a significant improvement for attaching metal parts to metallized ceramic surfaces.

Abstract Hermetically sealed ceramic metal connection, whereby in particular ring-shaped parts made of metal (3, 4) or metal alloys and ceramics (1) Are connected by butt soldering, adding multiple soldering one behind the other (5) on the webs (6) of profile-like hollow metal bodies (3) open on one side are made at the connection point to the metallized ceramic part (2). Of the metallic hollow body (3) can be U-shaped (3a) or comb-like (3b) Q u'rs cut. Alumina is mainly used as the ceramic material and metals such as molybdenum, copper, etc. or else are used for the metal hollow body (3) Metal alloys such as Fe-Ni-Co compounds are used. Within the scope of the invention are In addition to copper / silver / gold solders, low-melting brazing alloys can also be used.

The summary refers to Figure 1 of the drawings. L. e e r e i t e

Claims (5)

P a t e n t a 11 s p r ii c h e 1. Hermetically sealed ceramic-metal connection with high strength, with the parts made of metal or metal alloys and ceramics, preferably aluminum oxide, connected in the manner of butt soldering, thereby characterized that one behind the other multiple soldering (5) on the webs (6) of hollow profile-like metal bodies (3) open on one side at the connection point to the metzllized ceramic part (2) are made. 2. Hermetically sealed ceramic-metal connection according to claim 1, characterized characterized in that the hollow metal body has a U-shaped shape (3a). 3. Hermetically sealed ceramic-metal connection according to claim 1, characterized characterized in that the hollow metal body has a comb-like cross section (3b). 4. Hermetically sealed ceramic-metal connection according to claim i - 3, characterized in that the wall thickness of the webs (6) to the cavity of the hollow metal body (3) has a ratio of 1: 5. 5. Hermetically sealed ceramic-metal connection according to claim 1 - 3, characterized in that the distances between the webs (6) are 3 to 4 times the web thickness be.