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Independent UKAS Approved Analytical Service
Warton Metals offer customers
the opportunity of regularly monitoring the quality of the
solder in their machine and production lines, by analysing
a sample of their cored solder wire, solid solder wire, solder
alloy and lead free solder alloys. For completely unbiased
results, Warton use an independent UKAS approved assay
office. UKASs reports and certificates are accepted throughout
the world.
Why Do An Analysis?
A solder bath or pot can become contaminated in various ways. The solder can already include impurities when received, especially if the supplier uses re-cycled materials, or it may become contaminated over a period of time by leaching copper and other contaminants from the work being soldered.
Many contaminants such as silver and bismuth are not specifically detrimental in small quantities, therefore are only an indication of the purity of the solder. Contaminants such as aluminium, cadmium and zinc however are very detrimental to the performance of the alloy. Non metallic impurities such as sulphur and phosphorous are dangerous to the solder in as much as they can cause de-wetting conditions.
Some inclusions can be considered as either alloying additions or contaminants depending on particular applications. Other inclusions must be avoided at all costs. A description of the effect of impurities in a solder bath, some common contaminants and how they can have an effect on solderability, dross creation, joint formation and wetting ability are shown in the table opposite.
Contamination Problems that can arise
Aluminium: |
As little as 0.005% may increase dross rate without affecting joint formation. 0.001% may result in a sluggish or gritty solder. No solid solubility of aluminum in tin or aluminium in lead. |
Antimony: |
Certain of the specifications require the intentional addition of antimony. Ostensibly this is to retard the transformation of tin into its grey state, sometimes known as `tin pest'. However this argument no longer appears to have validity in a eutectic or near eutectic alloy. |
Arsenic: |
0.03% can cause dewetting but arsenic is not usually a contaminant in electronic applications. |
Bismuth: |
0.5% has been observed to cause some discoloration and oxidisation of solder, but appreciable amounts of bismuth would not normally be present in high quality electronic grade alloys or finishes. Bismuth can be added to increase spread or to dull joints otherwise bismuth is a contaminant which increases oxidisation. |
Cadmium: |
A levels of 0.002% joint formation will be noticeably affected. At 0.005% there will be a high incidence of bridging and icicling, together with a deterioration in joint strength and a reduced rate in spread. Also a health risk if high percentages are present. |
Copper: |
Can increase the rate of spread slightly but over 0.25% copper or even less joint formation will have deteriorated and could lead to dewetting and grittiness. |
Gold: |
At levels of 0.1% and quite often even less, the solder becomes sluggish and dull joints are formed. |
Iron: |
0.02% of iron can make joint formulation gritty. |
Sulphur: |
As little as 0.001% may inhibit wetting and produce grittiness. |
Silver: |
Has little effect on the wetting properties of tin/lead solders although it can be added to suit certain applications. |
Zinc: |
The presence of zinc can cause dulling and increase bridging and icicling.
0.005% can cause lack of adhesion and grittiness |
Notes
When copper and gold in combination add to 0.25%, joint formation will usually have deteriorated. The effects of aluminium, cadmium and zinc are cumulative. If more than one element is present the following lower limits are suggested 0.0005%, 0.002% and 0.001%.
Using The Analysis Service
To analyse the quality of your solder bath, take a small sample (about the size of a fifty pence piece) from the wave of the solder machine an send it to Warton Metals. Each sample should have an accompanying ‘Application For Analysis’ filled in (Please see sample below). Extra copies of the Application For Analysis are available on request. Warton will send the sample to the Namas approved assay office and results should be with you within four working days. If any contaminants are present in the results, Warton will be happy to advise on a solution.
For more information contact sales@warton-metals.co.uk
The Company warrants only that the Goods will correspond as to the quality and description with the Company’s own specifications as set out in each product data sheet and all other terms conditions or warranties relating to the quality and/ or fitness for any particular purpose whether express or implied are excluded to the fullest extent permitted by law. It is therefore the Buyers responsibility to satisfy itself by inspection and testing of samples prior to placing any orders as to the purpose for which he requires the Goods and or particular conditions of use that will apply to the Goods and or the suitability or performance of the Goods when used in combination with any other Goods or materials, in any specific environment and in any process. In no event shall the Company be responsible for special, incidental or consequential damages, whether the claim is in contract, negligence or otherwise.
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