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Alloy Impurities Level

Recommendation of Lead free Impurity Level

The general guide of the impurity action level is noted in the tables below. The actual tolerance level is to be determined by the individual customers as to the permitted threshold for each element.

It is important to maintain the composition of the solder bath in Lead-Free wave and selective solder processes so that the solder properties will remain constant for effective soldering process. The main elements that should be closely monitored are Pb, Cu and Ag. It is recommended to have frequent pot analysis in order to take early action in the case of non-compliance or to ensure that the process yield is maintained.

 

LF-315X and SAC with low level silver recommended action levels

Element Action levels Cause and Effect
Sn BAL No Action level
Pb 0.10 RoHS Directive 2002/95/EC state a maximum Lead content of 0.1%. Any lead contamination above 0.3% is detrimental to the solder joints.
As 0.03 Dewetting occurs with level above 0.03%
Cu 0.50-1.00 SAC with low silver is tolerant to copper levels up to 1.00%. Low or no copper alloy should be added to maintain copper levels. Levels above 1.0% may cause bridging.
Bi 0.08-0.20 Lead Free alloys are tolerant to Bi up to 1.0%, however if levels above 0.20% are detected, check for possible contamination.
Zn 0.005 Levels greater than 0.005% may cause higher levels of bridging and icicling. Pasty dross will form as well as dross will increase when Zn level is high.
Fe 0.02 Greater than 0.02% Iron can be an indicator of pot erosion and may cause gritty joint formation that can cause bridging.
Ag 0.25-1.00 Silver levels of 4% are used in some SAC alloys, however if the levels in Ag rises above the permitted specification, then some investigations should be held to establish the cause. Solderability should not be affected.
Sb 0.20 Lead Free alloys are tolerant to Sb up to 1.0%, however if levels above 0.20% are detected, check for possible contamination.
Ni 0.05 Levels greater than 0.03% may start to slow the wetting speed and could affect the hole fill performance.
Level of 0.05% can be tolerated if performance is acceptable.
Cd 0.003 RoHS Directive 2002/95/EC state a maximum Cadmium content of 0.01%. However, levels of 0.003% may cause bridging and icicling.
Al 0.005 Levels greater than 0.005% may cause bridging and icicling and a greater level of surface oxidation and pasty dross in the solder bath.
 

LF-307 and SAC middle level silver recommended action levels

Element Action levels Cause and Effect
Sn BAL No Action level
Pb 0.10 RoHS Directive 2002/95/EC state a maximum Lead content of 0.1%. Any lead contamination above 0.3% is detrimental to the solder joints.
As 0.03 Levels greater than 0.03% can cause dewetting.
Cu 0.50-1.00 SAC with mid level silver is tolerant to copper levels up to 1.00%. Low or no copper alloy should be added to maintain copper levels. Levels above 1.0% may cause bridging for fine pitch assemblies.
Bi 0.20 Lead Free alloys are tolerant to Bi up to 1.0%, however if levels above 0.20% are detected, check for possible contamination.
Zn 0.005 Levels greater than 0.005% may cause higher levels of bridging and icicling. Pasty dross will form as well as dross will increase when Zn level is high.
Fe 0.02 Greater than 0.02% Iron can be an indicator of pot erosion and may cause gritty joint formation that can cause bridging.
Ag 2.00-3.50 Silver levels of 4% are used in some SAC alloys, however if the levels in Ag rises above the permitted specification, then some investigations should be held to establish the cause. Solderability should not be affected.
Sb 0.20 Lead Free alloys are tolerant to Sb up to 1.0%, however if levels above 0.20% are detected, check for possible contamination.
Ni 0.05 Levels greater than 0.03% may start to slow the wetting speed and could affect the hole fill performance. Level of 0.05% can be tolerated if performance is acceptable.
Cd 0.003 RoHS Directive 2002/95/EC state a maximum Cadmium content of 0.01%. However, levels of 0.003% may cause bridging and icicling.
Al 0.005 Levels greater than 0.005% may cause bridging and icicling and a greater level of surface oxidation and pasty dross in the solder bath.

 

 

LF-801 and Sn100C series recommended action levels

Element Action levels Cause and Effect
Sn BAL No Action level
Pb 0.10 RoHS Directive 2002/95/EC state a maximum Lead content of 0.1%. Any lead contamination above 0.3% is detrimental to the solder joints.
As 0.03 Levels greater than 0.03% can cause dewetting.
Cu 0.50 - 0.85 LF-801can operates at 0.8%, however for finer pitch assemblies bridging may increase at levels above 0.85%. Alloy with low or no copper should be added to maintain copper levels.
Bi 0.05 Lead Free alloys are tolerant to Bi up to 1.0%, however if levels above 0.05% are detected this indicates some contamination issues that should be investigated.
Zn 0.005 Levels greater than 0.005% may cause higher levels of bridging and icicling. Pasty dross will form as well as dross will increase when Zn level is high.
Fe  0.03 Greater than 0.02% Iron can be an indicator of pot erosion and may cause gritty joint formation that can cause bridging.
Ag 0.05 Silver levels of 4% are used in some SAC alloys, however if the levels in Ag rises above the permitted specification, then some investigations should be held to establish the cause.
Sb 0.1 Lead Free alloys are tolerant to Sb up to 1.0%, however if levels above 0.1% are detected, check for possible contamination.
Ni 0.01 - 0.10 Nickel should be maintain at 0.05 -0.06% for most effective performance. Levels greater than 0.1% may start to slow the wetting speed and could affect the hole fill performance.
Cd 0.003 RoHS Directive 2002/95/EC state a maximum Cadmium content of 0.01%. However, levels of 0.003% may cause bridging and icicling.
Al 0.005 Levels greater than 0.005% may cause bridging and icicling and a greater level of surface oxidation and pasty dross in the solder bath.