It’s time to reassess the optimal temperature for electronics manufacturing facilities.
Electronics manufacturing production sites are ideal places to be during the summer because they maintain controlled temperatures. It’s well known that 23°C (74°F) is the ideal temperature inside electronics manufacturing areas. However, when the outside temperature reaches 40°C (104°F), the air conditioning system may struggle to maintain this lower value indoors.
Many companies establish internal guidelines that outline the environmental conditions for electronics manufacturing, and it is the responsibility of facility management to maintain these values within specified limits. But are these values correctly defined? This is what we need to determine.
Sustainability in electronics manufacturing and good environmental practices benefit businesses, and companies are continually seeking to reduce electricity consumption by investing in more efficient reflow ovens or putting unused equipment on standby. Soldering materials with lower melting points are also being tested to further decrease energy usage. Typically, conventional lead-free solder paste must be heated to 240°C (460°F) inside reflow ovens to form a strong intermetallic layer. However, achieving this at just 180°C (356°F) would significantly cut electricity consumption and, ultimately, reduce manufacturing costs.
Similarly, air conditioning systems consume large amounts of energy to maintain lower temperatures in production areas. Many facilities are located in North Africa, where high temperatures are common, making it challenging to keep the production area at 23°C (74°F). We need to reassess what the optimal temperature for electronics manufacturing should be. During the summer months worldwide, up to 25% of electricity is consumed by air conditioning systems. Studies show that raising the AC temperature by just one degree at home can significantly reduce energy consumption. Likewise, we should determine the optimal temperature for electronics manufacturing facilities.
The surface mounted technology (SMT) process is more sensitive to temperature variations compared to back-end processes, so we will focus on it. The equipment used to assemble components on PCBs is primarily automated, with suppliers specifying a temperature range of 10°C to 40°C (50°F to104°F). It’s clear that the maximum acceptable temperature is not solely determined by the equipment.
During electronics assembly, several materials used are highly sensitive to temperature changes. Solder paste requires careful handling before being printed on the PCB. After receiving it from the supplier, it should be stored in a refrigerator for no more than six months, with usage following the first in, first out (FIFO) method. Before production, solder paste must undergo homogenization and acclimatization. Suppliers recommend maintaining a maximum temperature of 28°C (82°F) in the assembly area to preserve the material’s properties. If the temperature exceeds this limit, the acclimatization time needs to be adjusted. In some regions, the indoor temperature remains stable around 23°C (74°F) at night but can rise above 30°C (86°F) in the afternoon. Does this mean that the day shift should follow different acclimatization procedures than the night shift?
The IPC/JEDEC J-STD-020 standard specifies that the floor life of moisture sensitivity level (MSL) components is calculated based on a maximum 30°C (86°F) and 60% relative humidity. Under these conditions, a component with MSL level 4 can be stored on the SMT line for up to 72 hours before mounting and reflow. However, if temperature and humidity increase, the maximum floor life decreases. Is there a way to calculate this relationship between time, temperature, and humidity in real time?
We’ve already seen that lower temperatures are preferred for both equipment and materials. When we know that the environmental conditions inside the electronics manufacturing are not optimal, we better keep one eye on the solder printing process. It is a fact that 70% of the scrap generated on the SMT line is due to the solder paste printing process. While environmental conditions play a role, incorrect stencil design is the most common cause of this scrap.
Siemens Valor Process Preparation makes stencil design easier than ever. Simply import the CAD file, automatically generate the apertures, and export the CAM data to the stencil supplier. Even if a design for manufacturing check isn’t in place, the new ‘design for printing’ check function can detect design issues and allow you to adjust the stencil before starting the new product introduction process.
Let’s summarize and identify the upper temperature limits. The most temperature-sensitive equipment used in production can withstand up to 40°C (104°F). However, solder paste, the most sensitive material, has a maximum temperature limit of 28°C (82°F). In the electronics manufacturing industry, humans are the most sensitive to temperature variations. Even a fluctuation of ±2°C can make us uncomfortable. This sensitivity is an important factor to consider when establishing the minimum and maximum temperature limits.
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