IN Brief:
- Vision RCC preheats boards to about 210°C before condensation soldering in a sealed chamber.
- Vacuum treatment follows solder melting in the same chamber, with void content below 2% claimed under suitable conditions.
- The transport system handles assemblies up to 25 kg and the equipment supports MES connectivity.
Rehm Thermal Systems has introduced Vision RCC, a reflow soldering machine that combines convection preheating, condensation soldering and vacuum treatment in a continuous manufacturing process. The system is designed for complex electronic assemblies weighing up to 25 kg, where differences in component mass and thermal response complicate soldering.
Convection first warms the board to approximately 210°C, narrowing the temperature differences between small components and heavier copper structures before solder melting. Rehm heats the Galden transfer fluid for the next stage at the same time. By coordinating these operations, the company reports a soldering process up to 50% shorter than its reference arrangement, depending on the assembly and cycle being compared.
The preheated assembly then enters a sealed chamber, where injected Galden vaporises and condenses on exposed surfaces. Condensation delivers heat to the board without relying solely on circulating hot gas, and the fluid’s boiling point sets the maximum temperature available from that phase of the process. Large thermal masses can therefore continue receiving heat while smaller parts are protected from an uncontrolled rise in the heating medium’s temperature.
Temperature uniformity still depends on component geometry, substrate thickness and thermal coupling: the selected boiling point cannot make every joint reach soldering temperature simultaneously. Rehm varies the quantity of Galden introduced to control the heating gradient, allowing a profile to be adapted for dense components, heavy substrates and devices with tighter thermal limits. That adjustment links the initial convection stage to the subsequent condensation heating.
Once the solder has melted, the system removes Galden for recirculation and applies vacuum in the same chamber. Lower pressure helps release gas trapped in molten solder before the joints solidify, reducing void formation without another handling step. Under suitable process settings Rehm reports void content below 2%; joint geometry, solder materials and the selected cycle determine the outcome on a particular assembly.
Voids can impair thermal conduction across the solder interfaces used to attach power devices and other components with substantial heat loads. Their effect depends on void location and distribution as well as total void area, joint geometry, solder alloy and duty cycle. Accordingly, a low total void percentage does not by itself define the acceptance criteria for every product. Assemblies still require suitable inspection and reliability qualification for their intended operating conditions.
A three-part transport system carries assemblies weighing up to 25 kg through the machine without additional carriers. After the soldering chamber, a separately controlled cooling section allows the cooling gradient and final exit temperature to be set without dictating the timing of the preceding heating cycle. Controlled cooling helps manage the stresses produced when components, joints and substrates contract at different rates.
Vision RCC can run in air or nitrogen, with residual oxygen below 100 ppm specified for nitrogen operation. Reducing oxygen exposure during heating limits surface oxidation and can improve solder wetting, helping maintain joint quality across repeated cycles. Galden circulates through a closed purification and return system, supplying the condensation heating stage repeatedly rather than requiring fresh fluid for each board.
ViCON control software records the selected process settings and provides process analysis and traceability functions, with connectivity to manufacturing execution systems. These records can be linked to an assembly’s production history and compared with results from subsequent inspection. Where solder voids are hidden beneath components, X-ray inspection and the product’s own acceptance criteria still determine whether the finished joints meet requirements.
Power electronics and AI server assemblies can combine large copper areas, substantial components and densely populated boards, creating uneven thermal loads during reflow. Vision RCC addresses those loads through coordinated preheating, condensation heating limited by Galden’s boiling point and vacuum treatment, with adjustable cooling and atmosphere control. Its 25 kg handling capacity and manufacturing system connectivity define how the equipment can be integrated into production lines for these assemblies.
