Lead Finish Guides - Page 1 of 2: Tin Plating Troubleshooting

Lead Finish Troubleshooting Guides

Tin plating and solder plating are two common lead finish processes used in semiconductor manufacturing. The following tables serve as quick references for troubleshooting problems related to these processes. Table 1 is a troubleshooting guide for tin plating processes, while Table 2 is intended to help with solder plating processes.

Table 1. Troubleshooting Guide for Tin Plating

Problem	Cause(s)	Remedy
Formation of Dendrites	Insufficient amount of brightener/ additives/replenishment chemicals	Add more brightener/ additives/replenishment chemicals
Formation of Dendrites	Insufficient amount of acid	Add more acid (usually sulfuric acid)
Formation of Nodules	Presence of solids in bath	Filter the bath
Graininess	Insufficient replenishment of additive chemicals	Add more replenishment chemicals
Graininess	Insufficient amount of metal	Add stannous sulfate
Burning	High plating current	Decrease the plating current
Blistering	Inadequate or poor cleaning	Perform proper cleaning
Pitting	Insufficient replenishment of additive chemicals	Add more replenishment chemicals
Reduced Throwing Power	Insufficient replenishment of additive chemicals	Add more replenishment chemicals
	Insufficient amount of acid	Add more acid (usually sulfuric acid)
	Insufficient amount of metal	Add stannous sulfate
Gassing	High plating current	Decrease the plating current
Gassing	High plating voltage	Decrease the plating voltage
Anode Polarization	High plating current	Decrease the plating current; add anode
Formation of Brittle Deposits	Organic contamination	Conduct carbon treatment

Table 2. Troubleshooting Guide for Solder Plating

Problem	Cause(s)	Remedy
Poor Solderability	Organic contamination	Perform carbon treatment
	Inadequate plating thickness	Increase the plating thickness
	Metallic contamination (Cu > 50 mg/l)	Subject the bath to dummy plating
	Excessive additive content	Dilute the bath or perform carbon treatment
	Br > 20 mg/l	Dilute the bath
Low CD Dullness	High metal content	Adjust the bath; use inert anode
	High bath temperature	Cool the bath to 65 deg F
	Insufficient amount of acid	Add more acid
	Cl > 150 mg/l	Dilute the bath
Over-all Dullness	Insufficient amount of additives	Increase additive content
	Low plating current	Increase the plating current
	High bath temperature	Cool the bath to 65 deg F
	I > 5 mg/l	Dilute the bath
Poor Throwing Power	Insufficient amount of additives	Increase additive content
	High metal content for current used	Adjust the current; dilute the bath
	Insufficient amount of acid	Add more acid
Low Cathode Efficiency	Low metal content for current used	Adjust the current; increase the metal content
Low Cathode Efficiency	Insufficient amount of acid	Add more acid
Pitting in High Current Areas	Insufficient amount of additives	Increase additive content
Pitting in High Current Areas	Low metal content for current used	Increase the metal content
Tarnishing	Improper rinsing	Perform post-rinsing
	Low plating thickness	Increase plating thickness
	Pre-plate contamination	Eliminate pre-plate contaminants
Anode Polarization	Presence of sludge in the bath or basket	Filter the bath; clean the anodes
Burning	Insufficient amount of additives	Increase additive content
	High plating current	Decrease the plating current
	Low metal content	Increase the metal content
Cloudy/Turbid Solution	Presence of stannic tin in the bath	Subject the bath to appropriate treatment
Cloudy/Turbid Solution	Presence of chlorides or sulfates in the bath	Filter the bath and eliminate the source of chlorides and sulfates
Roughness	Presence of stannic tin in the bath	Subject the bath to appropriate treatment
	Presence of insolubles in the bath	Filter the bath
	Presence of lead precipitates in the bath	Filter the bath and eliminate the source of precipitates
Foaming	High additive content	Perform carbon treatment
Sn/Pb Ratio Problems	Incorrect bath	Adjust the bath composition
	Poor bath agitation	Increase bath agitation
	Presence of nitrates in the bath	Dilute the bath and eliminate the source of nitrates

See also: Lead Finish; Pb-free Manufacturing

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