Nodules are protrusions over the plated surface. They are usually small  in 
nature and maybe conical, round or needle like. 
There are some known causes for nodulation: 
The first and foremost is the introduction of “particles into the  bath” 
that actually land on the plating surface. They offset the uniformity  of crystal 
growth and create surface imperfections. One example is a torn anode  bag 
that lets loose copper oxide fines into the bath, this gives rise to a sand  
paper effect. Another is the introduction of fine carbon particulates after  
C-Treat. The nodules formed here would have carbon in their core. 
Second, is surface irregularities coming to the plating line. These could  
come from the deburr operation after drill and or from surface preparation at  
dry film lamination. Shadow/electroless residues on the surface could 
contribute  to this problem  
Third, “Unusual Crystal growth” is the other cause. If the source  of 
nodulation is uncontrolled crystal growth, the answer will be found in  manipulating 
the additive package. 
During deposition cystal growth is controlled by the additive package.  The 
additive is compromised of three components: 
Brightener 
Carrier 
Leveller 
The carrier function is to create suppression and that is make it harder  to 
plate, when this happens the plating is forced to get organized into a  
crystal lattice and creates good adherent plating. The cost of suppression is  
increased plating voltage. The more suppression the better the surface and thru  
hole copper thickness distribution.  
The leveler serves a somewhat similar function to the carrier, it further  
suppresses plating in the higher current density areas allowing the lower  
current density areas to catch up. 
The brightener is the ultimate grain refiner. Without the brightener the  
plating would be dull and any imperfections would be pronounced. The brightener  
controls the crystal formation thru grain refinement and hence the brightening 
 effect. 
Nodule Solutions: 
If the source is extraneous material then the obvious answer is to  prevent 
the material from coming to the tank and if it does then to have way to  
quickly remove it  (adequate  filtration). Air could be a source, carbon from 
C-Treat could be another, as  well as sludge from the anode bags. The insoluble 
anode would eliminate anode  sludge from the picture. 
If the nodules are a result of surface imperfections, these need  to be 
identified and eliminated. 
If  the nodules belong to the third type then the correction will be thru the 
 upgrading of the chemical additive system and its control.
 
 
Best  regards

George Milad
[log in to unmask]
National Accounts Manager  for Technology
Uyemura International Corporation
Technical Center
240  Town LIne Rd
Southington CT 06489
(516) 901 3874 (mobile)
(860)  793-4011 (office)
(860) 793-4020 (fax)

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