The metallurgical bonding of materials without flux is very difficult from 140 oC. Oxide formations generally preclude wetting of the surfaces to be brazed. Fluxes that break up or dissolve the oxides are unavailable. These are also absolutely undesirable where high demands are set, e.g. on the purity of the components or the quality of the solder joints.
Furthermore, stress problems must be taken into account, especially when materials with different coefficients of thermal expansion have to be joined together.
ColdBond® offers process technology options for solving these difficult tasks and meeting the high requirements, thanks to the following features:
In, Bi, Sn or even AuSn solders are used as solders. Preforms are generally preferred to solder pastes. Materials that are difficult to wet, such as light metals, ceramics or glass, are metallized in advance, e.g. with Ni, Ag, Au or Pt. The demands on the soldering process are very high. Superimposed solders, for example, should not be used. "Fresh" solders with high purity requirements are generally used.
The surfaces of the components must be very clean before the joining process. For this reason, they are cleaned in advance with considerable effort. The components are handled in clean room-like conditions. Contamination of the components, e.g. by finger oil or dust, must therefore be absolutely avoided.
The latest nano/micro material developments based on Ni, Cu or Ag are implemented with ColdBond® using process technology. In addition to these soldering variants, pressurized (5 MPa to 35 MPa) and unpressurized sintering are also viable options. In recent years, sintering with Cu and Ag pastes has increasingly established itself as a reliable bonding technology.
With ColdBond® this can now also be implemented in vacuum or active gas. Sintering pastes from established suppliers are used as well as products developed in-house, which are tailor-made for special customer requirements.
Aktuelle Anwendungen finden sich in den Bereichen Elektronik, Sensorik und Optik. Ein weiteres Einsatzgebiet ist die Verwendung thermisch empfindlicher Materialien im Formenbau, bei Heiz-/Kühlleitern, im Wärmemanagement und in der Medizintechnik.