DE10240355B4 - Composite component and method for producing a composite component - Google Patents

Abstract

Composite component, at least two bodies by a flux-free solder cohesively connected to each other, while the solder joint with on complementary surface areas the body applied thin-film system is formed, starting from the respective body in each case at least one of Titanium existing first adhesive layer comprises, in each case at least one Barrier layer, taking the body and closest to the adhesive layer first barrier layer is made of platinum; and a common solder layer from a gold-tin alloy includes, and at different surface areas of the body the Gold-tin solder layers are provided, such that the solder layers different Gold and tin mass% ratios and thereby have different melting temperatures.

Description

The The invention relates to a composite component and to a production method, at least two bodies through a solder joint cohesively with each other are connected. It is a high-precision joining method, at least two bodies permanently connected with each other with very high positional accuracy can be.

For many Applications in which certain bodies permanently cohesively with each other can be connected Material-related in the conventional joining methods only limited heat entries made and accordingly, certain upper temperature limits are not exceeded become. So must in almost all cases the melting temperature of the materials of bodies so interconnected should be left unchecked. Especially with a corresponding Connecting optical elements may cause a corresponding heating as well not too elevated Residual stresses in the material, which can lead to cracks or even complete destruction achieved become. Furthermore must with optical elements the transformation temperature at Be fallen below.

The heat problem is therefore among the common ones cohesive joining methods welding and soldering to be observed.

at usually for Solder joints used usual Soldering also requires the addition of fluxes, which are the Positioning accuracy and the cleanliness of the optical functional surfaces, in particular in the joint gap area.

There in the production of cohesive solder joints, the required Maximum temperatures usually below those for the formation of welded joints required is the soldering for many application cases and in particular in the already mentioned optical and semiconductor elements across from welding to prefer. In solder joints but is also the adhesive strength on the surfaces the body to be joined together is problematic, so that by soldering produced cohesive Connections reach only limited tensile and shear strengths can.

Out US 5,622,788 a soldering process and a correspondingly produced article is known.

at this solution should be on a surface of a with another body to be connected to another body a layer system can be applied. This layer system exists of at least one adhesion layer of titanium, a barrier layer platinum, another costly layer of pure gold, and a layer consisting of a eutectic gold / tin alloy. On the gold / tin layer is directly the surface of the to be connected body put on and the cohesive Connection through conventional Soldering made. Furthermore, in the barrier layer is a window for recording be present of the actual solder, so that the production accordingly must be done.

One Such construction takes place in the form of so-called "bumps", as is customary in the production selective electrically conductive connections to semiconductor devices be used.

Furthermore, a method of attaching fibers to optical devices in JP 57029021 A described, are used in the metallic solder layers, which lead by the influence of laser beams to a cohesive connection. The actual solder layers are formed together with several other layers, as a layer system. The solder layer should consist of a gold / tin alloy.

Out EP 0 517 369 B1 Opto-electronic components are known in which compounds are also to be produced by soldering. The solder to be used is a eutectic gold / tin alloy. The solder connection is formed pointwise over so-called pads and Lötbuckel (bumps).

at cohesive Compounds that have been made by gluing can often do that addressed heat and temperature problem are sufficiently taken into account. The at Stiffening shrinkage, but in turn has a negative effect on the positioning accuracy of the so interconnected body. Furthermore you can Problems due to different wetting behavior due to sticking interconnected body, as well as the different thermal expansion coefficients of primer and body materials occur. Furthermore the adhesion promoters have a limited temperature stability.

It is therefore an object of the invention, a composite component and a manufacturing method for such To propose composite components, with the at least two bodies cohesively through Soldering with high precision, with increased Shear strength and increased temperature stability permanently can be connected to each other.

According to the invention this Task with a composite component that has the features of the claim 1 and a manufacturing method according to claim 13, solved. advantageous Embodiments and developments of the invention can with designated in the subordinate claims Characteristics can be achieved.

The composite component according to the invention, at least two bodies through a solder joint cohesively connected to each other, opposite, conventionally produced solder joints high strength, in particular the shear strength, on and it can be a very high positioning accuracy of each other so connected body be achieved in relation to each other.

The exhibit body to be joined together for the Formation of the solder joint on complementary surface areas each a thin-film system on. This thin-film system exists at least one titanium adhesive layer, a platinum barrier layer and a solder layer of a gold-tin alloy. Under complementary surface areas should be the for the cohesive Connection exploited part of each body can be understood. So can be a thin film system on the whole for the cohesive Connection usable surface of the respective body be educated. But there is also the possibility of the body surface through Structuring with the thin-film system form in the form of a Ras ters or in ring or strip form, wherein in these cases then the corresponding surface areas of the other body to be joined at least in the same Form are coated so that the solder layers of each other to be connected body in touching Contact each other.

The forming the composite component according to the invention body can for example, with precise computer-controlled Manipulators positioned in relation to each other, optionally in fixed to these positions and the solder joint by a corresponding Warming, with subsequent cooling, the leads to the solidification of the solder material, cohesively with each other get connected.

Around the for the soldering To minimize the required maximum temperature as much as possible can be advantageous a eutectic gold / tin alloy with 80 mass gold and 20 mass% Tin for the solder layer can be used. With such an alloy, the Temperatures for the soldering below 300 ° C being held.

According to the invention, different surface areas of bodies, the cohesively too a composite component to be connected to each other, with a Lotschicht coated, the different mass -% - ratios of gold and tin. So usually with an increased mass% Proportion of Gold in a Gold / Tin Alloy Melting Temperature Required for Soldering compared to a previously mentioned increased eutectic alloy be. This opens up the opportunity different bodies successively with the same joining technique to form a composite component to add. So can for example, two bodies, which are provided with a non-eutectic gold-tin alloy as solder layers are at an elevated level soldering temperature to a partial composite component, be joined at a brazing temperature above 300 ° C. and then at least another body with one or more bodies cohesively get connected. Here are then used for this connection Lotschichtbereiche formed from a eutectic gold-tin alloy, so they work at a lower soldering temperature below 300 ° C without the pre-attached Solder joints are affected, can be connected to each other.

at according to the invention on the Trainee body surfaces Thin-film systems can advantageously at least one second adhesive or barrier layer between the adhesive and the solder layer are formed. It turns out accordingly a layer rim adhesive layer, first barrier layer, second adhesive or barrier layer and solder layer.

So may be the second adhesive layer of titanium in elemental form or a second barrier layer may be formed of titanium nitride.

Especially in metallic materials of bodies, it is favorable, a to use such a second titanium nitride barrier layer.

The Thickness of the adhesive layers should be at least 20 nm, preferably about 30 nm, the thicknesses of the barrier layers at least 50 nm, preferred 100 nm and the thickness of the solder layer at least 2.5 microns, preferably at least 3 μm to reach.

The on the cohesive material to be joined bodies trained thin-film systems can with various known per se CVD or PVD vacuum coating process be formed.

Particularly advantageously, the individual layers forming the thin-layer system can be successively formed successively from the different materials in a single vacuum chamber, without performing an intermediate flooding. This is also true for a reactive formed titanium nitride barrier layer too.

So can be used according to the invention thin-film system on the bodies produced within a vacuum chamber by DC magnetron sputtering be, in which case for each individual layer within the vacuum chamber has a separate one Sputter source can be present and the respective body, for example moved by moving a suitable carrier from source to source becomes.

For compliance the desired high positioning accuracy of the body to be joined together should on the respective body the thin-film system have a constant thickness, this on the total thickness and preferably also the thickness of the single layers should apply. This means, that the layer thickness at all points of the corresponding surface of the body is constant. However, it is not mandatory that the layer thickness of the thin-film system on the at least two bodies to be joined together too is the same.

Especially for the increase the adhesion of the thin-film systems on the appropriately coated bodies and accordingly also a total increased Shear strength of the solder joint, it is advantageous at least the surface areas on which the Thin-film system formed should be, in advance by dry etching modify. This can preferably by ion bombardment with a Argon plasma performed be, with the surface modification also in the same vacuum chamber, without interim Flooding can and should be done.

With Such a coating variant may also include chemical reactions the layer materials used are avoided. And besides that lies it is obvious that by doing so, as well as by abandoning one Gold intermediate layer the cost can be reduced.

at of the invention body Made of a variety of materials to a composite component permanently cohesively get connected. The body can for example, made of glasses, Ceramics and metals are made. So bodies can be the same, as well made of different materials.

The Invention leaves very beneficial for the production of composite components, in which at least one the body an optical element is to use. For example, optical lenses or optical filters with a socket made of a different material get connected.

It can body made of glass, e.g. BK7, silver glasses, optical glasses, glass ceramics but also metallic bodies be made of copper or aluminum to form a composite component.

Next the already mentioned optical elements can but also optical waveguides be a body for the composite components. So can For example, optical fibers are connected to an optocoupler. In this case, then the respective thin-film system is at least partially on the respective inner and outer lateral surface of this optical elements, as an example of body formed.

The actual cohesive Connection of the respective composite component forming body can considering the materials and body geometries used. there can they mechanical strength, the optical, thermal and electrical Properties are taken into account.

So of course exists the possibility, in relation to each other positioned and fixed body in a conventional one Oven, on the for the Soldering required To heat temperature, where in this case all parts and areas of all such a composite component forming body down to the soldering temperature heated become.

Especially with sufficient mechanical strength of the materials of each other to be joined Body, but also the connection by diffusion soldering, be carried out at a reduced soldering temperature.

For the production a composite component with at least one optical element but it is advantageous, the solder joint by laser soldering or by induction fetuses manufacture.

So can a correspondingly focused and guided laser beam along a joining gap be moved and so its high energy density only in this tight limited area act.

at one for the wavelength of the laser beam transparent material, the laser can also through the body material on the thin-film systems directed and possible in the field of each other actually cohesively be focused to be joined solder layers.

Induction soldering is particularly suitable when the bodies to be joined together consist of dielectric materials in which no eddy currents can be induced. This can almost exclude with a suitably designed inductor of the heat input Lich in the two thin-film systems and the other heat ranges only increase their temperature by heat conduction. In this case, the known in dielectric materials poor heat conduction can be advantageously exploited. The induction brazing is particularly advantageous to use when one of the body is cylindrical in the part to be joined and a cylindrical opening formed in the other body.

following should be examples of the training of thin-film systems on surface areas of composite components forming bodies described in more detail become.

In this case, a body made of a variety of materials, some examples have been previously designated, coated within a vacuum chamber at a working pressure of about 2 × 10 ^-3 mbar and previously the surface be modified by dry etching, for example by RF sputter etching.

It be for this used the DC magnetron sputtering.

The dry is used with argon as working gas, at a power of 500 W over one Period of 180 s performed.

Of the Distance between body surface to be coated and the target should be at 65 mm.

After this the body surface has been modified is, the thin film system can be formed. At the same time the working pressure on which already designated Value and with a sputtering power of 800 W first the Titanium adhesive layer with a sputtering rate of 2.5 nm / s with a layer thickness of 30 nm formed.

Subsequently, will the platinum barrier layer with a sputtering power of 500 W, with a sputtering rate of 2.2 nm / s with a layer thickness of 100 nm formed.

On this barrier layer then becomes a eutectic gold-tin target the solder layer has a sputtering power of 800 W, with a sputtering rate of 10 nm / s formed to a layer thickness of 3.5 microns.

at a second example of one on a body usable thin-film system was between the solder layer of the gold-tin alloy and the first barrier layer of platinum a second adhesion layer of titanium, formed with a layer thickness of 15 nm. The same process parameters were used complied with, which also in the formation of the adhesive layer of titanium have been used.

at a third example was a thin film system with an adhesive layer Titanium, platinum first barrier layer, titanium nitride second barrier layer and solder layer of gold-tin alloy applied to a body.

For training the adhesive layer of the first barrier layer and the solder layer was as in the previously described examples procedure.

The Titanium nitride layer with a layer thickness of 30 nm is with use a titanium target and reactively formed by the supply of gaseous nitrogen. The sputtering power was set to 800 W and a sputtering rate for the achieved titanium nitride of 2.2 nm / s.

For this thin-film systems was the adhesion on glass bodies by means of Tapetest (ISO 9211-02-03-01) carried out.

at by soldering cohesively connected bodies Shear strengths of at least 100 MPa have been achieved on glass, in the range of conventional brazed joints lie.

at The composite components produced in this way could no delay the connected bodies and also due to the flux freedom a high joint and positioning precision the correspondingly connected body are adhered to.

The Shear strength was measured on glass bodies whose planar surface areas by laser soldering have been connected, determined. These became punctual with each other connected, with multiple solder points have been trained. There was also a test on annular contours carried out.

For the measurement was used a shearing device, which is a force introduction in the Lotschichtbene, perpendicular to the surface normal of this level allows and prevents tilting of the interconnected glass body. The force application was done with a tensile compression testing machine Instron and the maximum forces were used with a 2kN load cell certainly. It could shear strengths, based on the respective cohesively connected surfaces be determined above 100 MPa.

Claims (25)

Composite component, in which at least two Kör are cohesively interconnected by a flux-free solder joint, while the solder joint is formed with on complementary surface regions of the body applied thin film system, each comprising at least one existing titanium primer layer from the respective body, each at least one barrier layer, wherein the body and the Adhesive layer closest first barrier layer made of platinum; and a common solder layer of a gold-tin alloy, and at different surface areas of the body, the gold-tin solder layers are provided, such that the solder layers have different gold and tin mass% ratios and thereby different melting temperatures. Composite component, characterized in that at least a solder layer of a eutectic gold / tin alloy with 80 Mass% gold and 20 mass% tin is formed. Composite component according to claim 1 or 2, characterized that between the first barrier layer and the solder layer, a second Adhesive layer is formed. Composite component according to one of claims 1 or 2, characterized in that between the first adhesive layer and Lotschicht a second barrier layer is formed. Composite component according to claim 3, characterized that the second adhesive layer consists of titanium. Composite component according to claim 4, characterized the second barrier layer consists of titanium nitride. Composite component according to at least one of the preceding Claims, characterized in that the adhesive layer (s) has a thickness of at least 20 nm / have. Composite component according to at least one of the preceding Claims, characterized in that the barrier layer (s) has a thickness of at least 50 nm. Composite component according to at least one of the preceding Claims, characterized in that at least one of the bodies is a optical element is. Composite component according to at least one of the preceding Claims, characterized in that at least one of the bodies is a Optical fiber is. Composite component according to at least one of the preceding Claims, characterized in that the cohesive solder joint on the entire usable surface the body is trained. Composite component according to at least one of the preceding Claims, characterized in that the thin film system in the form of a structuring on the surface the body are formed. Method for producing a composite component, at least two bodies by a flux-free solder cohesively be connected to each other, when on the body, up each complementary surface areas one of at least one titanium adhesive layer, at least a barrier layer, wherein the closest to the respective body first layer is made of platinum, and one consisting of a gold-tin alloy solder layer formed thin film system is formed by vacuum coating method; being on different surface areas the body different gold-tin solder layers are formed in their composition, such that the areas have different mass% ratios of gold and tin, then the bodies are positioned to each other be that the coated surface areas with their solder layers in touching Contact stand and the solder joint by one the different melting temperatures of the different Mass -% - conditions the gold-tin alloy considered heat input is produced successively. Method according to claim 13, characterized in that that the thin-film system on the body is applied in a vacuum chamber. Method according to claim 13 or 14, characterized that the thin-film system through DC magnetron sputtering is formed. Method according to at least one of claims 13 to 15, characterized in that the surface to be coated of the body in advance by dry etching is modified. Method according to claim 16, characterized in that that the surface modification by Internal bombardment is carried out with an argon plasma. Method according to at least one of claims 13 to 17, characterized in that between the first adhesive layer and the solder layer at least a second adhesive layer made of titanium is brought. Method according to at least one of claims 13 to 17, characterized in that between the adhesive layer and the Lotschicht a second barrier layer of titanium nitride is formed. Method according to at least one of claims 13 to 19, characterized in that at least one eutectic gold-tin alloy with 80 mass% gold and 20 mass% tin used for the solder layers becomes. Method according to at least one of claims 13 to 20, characterized in that the solder joint is produced by laser beam soldering. Method according to at least one of claims 13 to 20, characterized in that the solder joint within a Furnace is made. Method according to at least one of claims 13 to 20, characterized in that the solder joint produced by induction soldering becomes. Method according to at least one of claims 13 to 23, characterized in that the thin-film systems with a constant layer thickness can be applied to the body. Method according to at least one of claims 13 to 24, characterized in that solder layers with a layer thickness of at least 2.5 μm be formed.