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Warton Metals offer customers the opportunity of
regularly monitoring the quality of the solder in their machine, by analysing a
sample of their solder. For completely unbiased results, Warton use an
independent Ukas approved assay office. Ukas 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:
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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. |
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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. |
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Arsenic: |
0.03% can cause dewetting but arsenic is not usually a contaminant in
electronic applications. |
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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. |
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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. |
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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. |
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Gold: |
At levels of 0.1% and quite often even less, the solder becomes
sluggish and dull joints are formed. |
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Iron: |
0.02% of iron can make joint formulation gritty. |
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Sulphur: |
As little as 0.001% may inhibit wetting and produce grittiness. |
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Silver: |
Has little effect on the wetting properties of tin/lead solders
although it can be added to suit certain applications. |
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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.
APPLICATION FOR ANALYSIS (sample)
A separate application form must be made out for each sample.
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Name of applicant:...............……………….......................Position:...........................................
Company:....................................................................................................................
Tel:........................................................................Fax:................................................
Date sample taken from
machine:.......................Applicants
sample identification.....
Make and type of
machine:.........................Bath
Capacity (Kg):..............................
Solder Type (alloy and
manufacturer):......................................................................
Flux
Type:...............................Operational
temperature of solder bath:..................
Unusual metals being soldered if unusual: Silver .....
Cadmium....Gold............Other....... (Please
tick as appropriate)
Date contents of solder bath last completely
renewed:............................................
Date and ref. number of latest previous analysis of this
machine.............................. |
The above sections must be completed in full.
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Element |
Symbol |
max. % |
result |
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Silver |
Ag |
2.0 |
RESULT |
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Aluminium |
Al |
<0.005 |
RESULT |
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Arsenic |
As |
0.03 |
RESULT |
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Bismuth |
Bi |
0.1 |
RESULT |
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Cadmium |
Cd |
0.005 |
RESULT |
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Copper |
Cu |
0.25 |
RESULT |
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Iron |
Fe |
0.02 |
RESULT |
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Antimony |
Sb |
0.5 |
RESULT |
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Tin |
Sn |
- |
RESULT |
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Lead |
Pb |
- |
RESULT |
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Zinc |
Zn |
0.003 |
RESULT |
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For Office Use Only
Report No:
Date:
Reference: |
To request a datasheet or to ask a
representative to contact you, please click on the INFORMATION
REQUEST FORM , E.mail support@warton-metals.co.uk
or phone: +44 (0)1706 218888.
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