Reduction of nitrogen consumption during convection soldering thanks to the patented mechatronic curtain from Rehm Thermal Systems
In electronics manufacturing, the diversity of component geometry poses a challenge: differences in assembly height require variable throughput heights in convection soldering systems. Current developments show a need for greater throughput heights due to the trend towards e-mobility, which in turn increases nitrogen consumption for process inerting. Rehm Thermal Systems responds to this problem with an innovative solution: the mechatronic curtain. This automatically adapts to the height of the assemblies, reduces energy and nitrogen losses and enables savings in EcoMode. The effectiveness of this technology is highlighted by the significant reduction in nitrogen consumption.
State of the art
Due to the diverse geometry of electronic components, the assembly height varies in the range of 5 to 30 mm. These differences lead to the requirement that the throughput height for a convection soldering system be specified as 30 mm upwards and 20 mm downwards. In addition, due to e-mobility, there is also a need for throughput heights of 50 to 100 mm upwards. This requirement means that the open area in the inlet and outlet of the convection soldering system becomes ever larger and as a result the consumption of the nitrogen necessary for process inerting increases drastically. This effect is particularly noticeable when soldering assemblies with different heights at the lower and upper limits. The “chicken feed” on the first page can serve as an example of this. The histogram in Figure 1 shows an example of the distribution of component height from a product mix on an SMT line.
Figure 1: Distribution of component height from a product mix
The histogram makes it clear that there are assemblies with a maximum total height of 30 mm and that the system must offer the necessary flexibility, but the quantity is very small. 90% of the components are no higher than 7 mm and it is therefore clear that for this product group the upper and lower throughput heights are oversized, which means that more nitrogen escapes from the system than would be the case if the curtains were designed to be optimized at this height.
Solution approach
In order to achieve both the maximum required throughput height and always optimal nitrogen consumption with lower assemblies, the mechatronic curtain was patented, developed and put into series production by Rehm Thermal Systems. Movable curtains are installed in the inlet and outlet of the oven, which always guarantee the optimal distance to the assembly depending on the assembly height.
Figure 2: Automatic adjustment of the top and bottom curtain to different assembly heights
Another advantage is that in the event of production interruptions, the system is switched to EcoMode, with the curtains completely closing the inlet and outlet. This means that less heat and nitrogen escapes from the system, which further increases the savings of EcoMode.
Benefit
Figure 3 shows the savings achieved through the measures. This is an assembly with 244 mm width, 305 mm length and 7 mm height. At 500 ppm residual oxygen, this measure saves approx. 27% of the nitrogen and at 1000 ppm approx. 20% of the nitrogen.
Figure 3: Comparison of N2 consumption for 500 and 1000 ppm residual oxygen target value
These test results show that the mechatronic curtain is able to realize both system flexibility and the increasingly stringent requirements for resource efficiency.
As a specialist in the field of thermal system solutions for the electronics and photovoltaic industries, Rehm is one of the technology and innovation leaders in the modern and economical production of electronic assemblies. As a global manufacturer of reflow soldering systems with convection, condensation or vacuum, drying and coating systems, functional test systems, equipment for the metallization of solar cells and numerous customer-specific special systems, we are represented in all relevant growth markets and, as a partner with more than 30 years of industry experience, we implement innovative solutions Manufacturing solutions that set standards.
Contact
Rehm Thermal Systems
Carmen Hilsenbeck
Leinenstrasse 7
89143 Blaubeuren
07344 9606 535
07344 9606 525