Hand Soldering and the impact of the RoHS （手焊和RoHS的影响）.pdf

Hand Soldering and the impact of the RoHS directive The adoption of the RoHS directive by the EU will mean that many manufacturers will need to change to using lead-free solders. Hand soldering with lead-free solders is relatively straightforward and it is possible to make good solder bonds as long as the differences between tin/lead and lead-free solders are understood. Differences All lead-free solders are different from traditional tin/lead solder as they have higher melting points and inferior wetting properties. Wetting will take a little longer and the solder tends to spread less. Also, most lead-free solders appear dull or matte in comparison with tin/lead, which is usually bright. Soldering temperature It is advisable to use as Iowa temperature as possible to minimise damage to heat sensitive components and maximise tip life. Start at 350°C and if good results are obtained, gradually reduce the temperature until it becomes impossible to make good solder joints -then, increase the temperature by 10°C. Note that solder wetting will take longer, be patient. If good solder wetting is impossible at 350°C, then gradually increase the tip temperature until good wetting is possible. Increasing the temperature can reduce wetting times but this will damage some types of components and shorten tip life. At present many operators hand solder at a high temperature to maximise productivity. In these cases, the same temperature could be used with lead- free solders but production of each joint will take a little longer. ComlJonentdamage Over-heating can damage many types of components. These include: Electrolytic capacitors Crystal oscillators