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The termination coatings of components are being changed from tin/lead to lead-free alternatives. The most common alternative is tin but tin alloys, nickel/palladium/gold and other materials are also used. Details of manufacturer and component availability are at www.arrow.com/green and from your Arrow representative .

Component issues

Components need to be chosen to ensure that they are RoHS compatible and so do not contain restricted substances. Some components will not be available in RoHS compatible versions and so in these cases redesign of the product will be required.

Many components are heat sensitive and can be damaged by high reflow temperatures. The maximum reflow temperature will be specified by the manufacturer and typical quoted values include:

Component	Max. temperature
Aluminium electrolytic capacitor – maximum temperature depends on size	240 - 250°C
Tantalum capacitor – various types	220 - 260°C
MLCC (ramp rate more important)	240 - 260°C
Film capacitor (depends on plastic film type)	230 - 300°C
SMT relay (plastic deformation)	226 - 245°C
Crystal oscillator (plastic deformation)	235 - 245°C
Connectors – depends on type of plastic used	220 - 245°C
LED – may function but light output affected	240 - 280°C
ICs	245 - 260°C

 

It is also important to note that the moisture sensitivity levels (MSL) of ICs will probably change so that shorter storage times after removal from packaging can be tolerated.

The implications are that when lead-free PCB production is planned components which are likely to be damaged by the higher temperature should be replaced if possible. In some cases redesign will be needed. This potential need for redesign is one of the main reasons why manufacturers should begin the development of RoHS compliant products now, as this can be very time consuming.

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