Vacuum soldering systems of the VLO line provide a voidless and fluxless reflow soldering. They create ultra clean soldered joints.

centrotherm covers the entire bandwidth of vacuum soldering system with its batch and inline systems. The customer specific vacuum soldering applications are much more demanding than the classic electronics of old. Today, you will see vacuum soldering applications in all ranges of microtechnology as well as in the fabrication of mechatronic products.

Picture 1: Soldered Joint with Voids

Picture 2: Soldered Joint without Voids

centrotherm vacuum soldering systems can operate at process temperatures of up to 650 °C. Due to the thermal transfer in the vacuum via contact or radiant heat, they offer an excellent temperature uniformity. The heat-up rate can reach 180 K/min and the cooling rate can reach 180 K/min. The vacuum and/or the pressure can be lowered to 10-5 mbar. The short cycle times allow a very high throughput while at the same time being economical about power consumption. The control system is a centrotherm Central Machine Control (CMC) which is operated with a self-explanatory, graphical user interface which is designed for intuitive operation. A consistent process traceability is possible due to a continuous data-logging process.

Voidless

During the soldering process, the pressure is reduced to 1 mbar (optional 10-5 mbar) in the liquid phase of the solder, this allows existing voids, which are in the solder and are still under normal pressure (DIN 1343 1013,25 mbar), to ooze outwards through the solder. This ensures a relative voidlessness of less than 2 % (optional less than 0.5 %) relating to the surface. Typical reflow soldering systems range at 20 %. In picture 1 we see a soldered joint with voids and in picture 2 we see a voidless soldered joint.

Flux Less

One of the main problems of the reflow soldering technology under atmosphere are the ever present oxide films on the solder depots and on the substrate. So stable processing in the reflow soldering technology also means getting rid of the oxides while avoiding oxidation of the soldering joint partners. Usually this is achieved using a fluxing agent. centrotherm, however, can do away with the fluxing agent in the vacuum soldering process using nitrogen (N2), forming gas (5% H2 & 95% N2), hydrogen (H2), formic acid (HCOOH) or by using a low pressure plasma with process gas.

Ultra Clean

The fluxless process keeps the build-up and soldering process partners clean. Using a controlled RF plasma with the corresponding process gas triggers an ultra cleaning process.