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What will happen if a sloder paste is used after 24hours

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#57807

What will happen if a sloder paste is used after 24hours | 17 January, 2009

what is the impact if a solder paste is used after 24 hours after tawing time

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#57809

What will happen if a sloder paste is used after 24hours | 18 January, 2009

We're not sure of the condition of your solder paste. So, afte 24 hours, if it's: * Unused, in a reclosed container, maybe a week of life depending on the environment * Used, scrap

A simple coalescence test can quickly determine the condition of solder paste after prolonged use. Simply print a small disk [around 4-5mm diameter and 0.2mm thick - a business card with a hole from a standard paper hole punch makes a good stencil] of paste onto a non-wettable substrate [eg, glass microscope slide, solder mask on board, ceramic tile], and re-flow as normal. A single solder ball in a clear pool of residue indicates good coalescing ability. Numerous solder balls remaining in the flux residue pool indicates poor coalescing ability and the paste may have become damaged. Note this is not an absolute test of the condition of the paste. It is only a first-line check and should only be used to confirm paste failures. [based on Multicore Solder Paste Handling Guidelines, September 2004]

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#57819

What will happen if a sloder paste is used after 24hours | 20 January, 2009

Depends on the solder paste. If it has been on the stencil for 24h there is a good chance that the paste is destroyed. You can however check if it has not dried out too much by letting the stencil printer do a few strokes and see if the paste still has good rolling properties and if the printed result is ok. A solderball test, as described in the post above, is also an indicator of the state of the paste. Never mix used and fresh paste to become better results, that does not work.

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#57820

What will happen if a sloder paste is used after 24hours | 20 January, 2009

MrDif: You don't add fresh paste to used paste? We add fresh paste to used paste on the stencil to replenish the paste consumed while printing boards, so that we maintain a nice thumb-size roll of paste. We change the used paste when we clean the stencil either: * End-of-production run ... OR * End-of-shift

We never add used paste to fresh paste.

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#57835

What will happen if a sloder paste is used after 24hours | 21 January, 2009

Sorry if that sentence there was not really clear. I meant: don't to try to 'revive' old paste or paste that has been on the stencil for a very long time using fresh paste.

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