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Kester Paste from Mexico

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Kester Paste from Mexico | 24 November, 2007

Just wondering if anyone else has had problems with Kester made from Mexico. We are seeing alot of bridging lately in our product.

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Kester Paste from Mexico | 26 November, 2007

I have been using it and noticed it seems to get runny after it has been out on the stencil awhile. Couple hours or so. At that point we've had some problems with the paste smearing on some fine pitch stuff(0.020"). I sped up my squeegee speed and it seemed to help solve the problem.

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Kester Paste from Mexico | 26 November, 2007

We had problems with their EM907 turning into a brick well before its expiration date. Since then, Kester has pulled EM907 production back to the United States (the last I heard) and we've switched our primary Pb-free paste vendor away from Kester.

With the 256HA that we use, which I believe is still produced in Mexico, we have had no issues that I am aware of.

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Kester Paste from Mexico | 26 November, 2007

It is the EM907 that we are currently using. All of the jars we currently have are made in Mexico. When did production move back to the US?

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Kester Paste from Mexico | 27 November, 2007

The letter below was dated December 13, 2006 from Kester's Senior Market Development Engineer. I guess since then they have moved production back to Mexico. We no longer use EM907 as our primary Pb-free paste so I haven't seen any containers in a while.

Prior to this issue we experienced with the paste turning into a brick, we had had an issue with its viscosity being too low. The print would bridge on fine-pitch components because it was being squeezed out between the foil and PCB. ----------------------------------------------------- ----------------------------------------------------- Gentlemen,

Kester recently experienced an issue with lots of EM907 made with a now known bad lot of a rheological agent. This raw material is a thickener that helps in areas of slump resistance and print definition. As with most raw materials in no-clean solder paste flux, outside of rosins/resins, this thickener sublimes as heated and is not present in anyway in post soldering flux residues.

The issue with the lot of thickener is that it experienced a very limited shelf life and hardened in a short period of time. Any issues experienced with the troubled lots would be purely on the print side of the process and will not affect the solder joint integrity or long-term reliability.

A recall of the lots in question was performed but unfortunately some of the material fell through the cracks. Kester apologizes for the mix up and we are doing all that we can to make sure that the issue will not happen again. Additional incoming QC checks have been implemented to ensure that the thickener is within specification limits. Full production of EM907 has also been transitioned back to our US facility.

I hope this is the information that you were looking for. Please let me know if you have additional questions or comments. -------------------------------------------------------- --------------------------------------------------------

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