Preliminary infrared desoldering tests
Some preliminary laboratory de-soldering tests of components from end-of-life lead-solder PCBs have been done using infrared radiation to melt solders. In these trials the PCB has been placed under a medium wave infrared emitter (4 lamps, 2.000 W/lamp) for 1-3 minutes. In some cases, the emitters was in front of the PCB side that contained the components, in other cases, the emitter heated the opposite side. Once the solders were melted a slight mechanical shake was required to disassemble the components and also part of solder was removed (Figure 6). Physical damages in packages have not been observed, but some boards laminates were deteriorated due to radiation.
Figure 6. End-of-Life PCB subjected to infrared radiation
Advanced infrared de-soldering tests
More tests of IR de-soldering with lead free solder and lead containing solder PCBs have been made. Two processes were researched. The first one was the mechanical disassembling explained below:
Physical damages in components (package) due to heat have not been observed, but connection pins can be damaged in the process. Some laminates have been deteriorated.
In the second procedure the de-soldred component has been removed automatically:
Figure 8. Infrared automatic disassemble
According to the experiments done, disassembling time depends on PCBs laminate type (heat transmission through laminate material), solder nature (longer time for lead-free solder PCBs) and distance between emitter and PCB. With this system whole PCB is heated and as a consequence some damages in laminates and components have been observed. This overheat of the laminates can give off toxic fumes.
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Desoldering Procedures for Electronic Components from PWBs
Some preliminary laboratory de-soldering tests of components from end-of-life lead-solder PCBs have been done using infrared radiation to melt solders. In these trials the PCB has been placed under a medium wave infrared emitter (4 lamps, 2.000 W/lamp) for 1-3 minutes. In some cases, the emitters was in front of the PCB side that contained the components, in other cases, the emitter heated the opposite side. Once the solders were melted a slight mechanical shake was required to disassemble the components and also part of solder was removed (Figure 6). Physical damages in packages have not been observed, but some boards laminates were deteriorated due to radiation.
Figure 6. End-of-Life PCB subjected to infrared radiation
Advanced infrared de-soldering tests
More tests of IR de-soldering with lead free solder and lead containing solder PCBs have been made. Two processes were researched. The first one was the mechanical disassembling explained below:
- PCBs placed under emitter for several seconds
- Emitter heats the PCB opposite side (no the components side), so components indirectly heated.
- Component temperature measured by thermocouples (using an automated data acquisition system)
- After heating immediately slight shaking is required to disassemble components (part of solder could be also removed).
Physical damages in components (package) due to heat have not been observed, but connection pins can be damaged in the process. Some laminates have been deteriorated.
In the second procedure the de-soldred component has been removed automatically:
- Vacuum extractor has been used to pick up components. The laboratory system is shown in Figure 8.
- The infrared emitter heats the PCB opposite side where the target component is, and thus, it is indirectly heated in order to reduce risks of damage due to radiation.
- Component temperature measured by Non contact IR thermometer
Figure 8. Infrared automatic disassemble
According to the experiments done, disassembling time depends on PCBs laminate type (heat transmission through laminate material), solder nature (longer time for lead-free solder PCBs) and distance between emitter and PCB. With this system whole PCB is heated and as a consequence some damages in laminates and components have been observed. This overheat of the laminates can give off toxic fumes.
Back:
Desoldering Procedures for Electronic Components from PWBs
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