With enormous increasing amount of electric and electronic equipment to be mass produced and therefore also to be disassembled, for example, when a specific component fails and it is replaced for a new one or at end-of-life to recover any valuable component to be used in a second life, it could be necessary to develop high flexibility and low cost disassembling procedures.
Currently, electronic components reuse from PCBs has some difficulties to be accepted due to:
In general, a basic disassembling process of electronic components from PCBs (lead containing or lead-free) for reuse purpose can be divided into three main steps:
In the task 4T2 different boards have been obtained in order to research the different technologies for de-soldering components . Lead containing PCBs were obtained from WEEEs (Waste electric and electronical equipment). Some units of lead free solder PCBs have been sent by Philips (partner 2) and Thomson (partner 4) for reuse and recycling study. The Thomson samples consist of several units of Pb-lead free PCBs with CEM3 and FR2 laminates and most of their electronic components are based on through hole technology (THT). On the other hand, the Philips samples consist of four types of lead-free solder (Figure 1) PCBs (board A, board B, board C and production board) that combine different lead-free solders, finish on board and component finish. The A, B and C types have surface mount components and in the production board most of them are through hole type. The PCBs from Philips the solders used are SAC (Sn95.5%-Ag3.8%-Cu0.7%), SACS (Sn95.25%-Ag3.80%-Cu0.70%-Sb0.25%) and SACBi2 (Sn93.5%-Ag3.8%-Cu0.7%-Bi2%). In Philips PCBs as finish on board have been used Cu-OSP (Cu with organic protection layer), Alpha-Ag (Cu with Ag) and Ni/Au (Cu with nickel and gold). The component finish are SnPb and Sn.
Figure 1. Philips lead free PCBs
On the other hand, the recovered components for reuse purpose must be subjected to a quality control in order to identify physical and electrical funcionality caused during the desoldering process. An artificial vision system and a universal trainer have been used in order to verify these components.
Desoldering of LQFP128 Components to be Reused in the EFSOT Verification Board [next chapter]
Currently, electronic components reuse from PCBs has some difficulties to be accepted due to:
- Reused components have bad image in market mainly because of uncertainly in their life span and reliability during the second use time.
- High recovery cost
- Lack of collection systems that guarantee constant supply
- Quite often product design does not allow easy disassembling of discrete electronic components.
- Lack of simple and effective disassembling processes for small or medium recycling industry.
- Absence of accepted quality standards for recovered components.
- Reticence of electronic industry to accept reused components in new products for technical and quality reasons. Reused components must fulfil the same requirements as new ones and also fit into standard manufacturing processes.
- Absence of established markets for recovered components
In general, a basic disassembling process of electronic components from PCBs (lead containing or lead-free) for reuse purpose can be divided into three main steps:
- Components identification on boards: by means of visual inspection or automatically with artificial vision systems.
- Desoldering and removal: by means of technologies like laser beam, infrared radiation, hot gas or vapour combined with removal systems like vacuum extractors or robots with specific picking tools. An important aspect to be considered when a component is de-soldered for reuse purpose is to avoid subjecting the package to high temperature (>230?C) for a long time (several seconds). High temperatures could kill sensitive components, for this reason in the laboratory de-soldering tests temperature of the components has been measured.
- Quality control: packages and connection leads must not be damaged. Leads have to fulfil requirements of co-planarity and alignment. For these purposes vision systems can be used for quality control.
In the task 4T2 different boards have been obtained in order to research the different technologies for de-soldering components . Lead containing PCBs were obtained from WEEEs (Waste electric and electronical equipment). Some units of lead free solder PCBs have been sent by Philips (partner 2) and Thomson (partner 4) for reuse and recycling study. The Thomson samples consist of several units of Pb-lead free PCBs with CEM3 and FR2 laminates and most of their electronic components are based on through hole technology (THT). On the other hand, the Philips samples consist of four types of lead-free solder (Figure 1) PCBs (board A, board B, board C and production board) that combine different lead-free solders, finish on board and component finish. The A, B and C types have surface mount components and in the production board most of them are through hole type. The PCBs from Philips the solders used are SAC (Sn95.5%-Ag3.8%-Cu0.7%), SACS (Sn95.25%-Ag3.80%-Cu0.70%-Sb0.25%) and SACBi2 (Sn93.5%-Ag3.8%-Cu0.7%-Bi2%). In Philips PCBs as finish on board have been used Cu-OSP (Cu with organic protection layer), Alpha-Ag (Cu with Ag) and Ni/Au (Cu with nickel and gold). The component finish are SnPb and Sn.
Figure 1. Philips lead free PCBs
On the other hand, the recovered components for reuse purpose must be subjected to a quality control in order to identify physical and electrical funcionality caused during the desoldering process. An artificial vision system and a universal trainer have been used in order to verify these components.
Desoldering of LQFP128 Components to be Reused in the EFSOT Verification Board [next chapter]
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