File name p29.pdfRepair Tips 109B2 GS3 CM25 29
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0. Warning 1.4 Attachment of SMDs
- Locate the SMD on the solder lands by means of tweezers and
All ICs and many other semi-conductors are susceptible to solder the component on one side. Ensure that the component is
electrostatic discharges (ESD). Careless handling during repair can Positioned correctly on the solder lands (see Fig.2A).
reduce life drastically. When repairing, make sure that you are - Next complete the soldering of the terminals of the component (see
connected with the same potential as the mass of the unit via a wrist Fig. 2B).
wrap with resistance. Keep components and tools also at the same
potential !
Fig. 2 MOUNTING
e.g. A PAIR OF TWEEZERS
1. Servicing of SMDs (Surface Mounted Devices)
1.1 General cautions on handling and storage A
- Oxidation on the terminals of SMDs results in poor soldering. Do not
handle SMDs with bare hands. SOLDER
0.5 - 0.8 mm
- Avoid using storage places that are sensitive to oxidation such as PRESURE
places with sulphur or chlorine gas, direct sunlight, high SOLDERING
IRON
temperatures or a high degree of humidity. The capacitance or
resistance value of the SMDs may be affected by this.
- Rough handling of circuit boards containing SMDs may cause
damage to the components as well as the circuit boards. Circuit SOLDERING TIME SOLDER
B
< 3 sec/side 0.5 - 0.8 mm
boards containing SMDs should never be bent or flexed. Different PRESURE
circuit board materials expand and contract at different rates when |