Found a good replacement for GC10...

[glenenglish]

I've switched over to
SAC305M8J5-T4-88.5%: Solder Paste SAC305    M8 88.5% 500g Jar
https://okay.com.au/product/aim-lead-free-sac305-m8-solder-paste-no-clean-500g-jar/

The batches I use are made in Sydney, Australia but its made all over....
It looks like T4.5 under the microscope, maybe they use a finer screen than GC10-T4

I like it better than GC10, doesnt slump as quick, seems like it doesnt dry out (evap)volatiles as quick) and I've had zero tobstones since using it. separates from stencil better, overall I like it. still OK at 25 deg C, also.
Be sure to  have a 'real' paste mixer. my soldering process is vapour phase.

Chemtools Pty Ltd
Unit 2/14 – 16 Lee Holm Road
ST MARYS, NSW, 2760
(PO Box 463 Emu Plains NSW 2750)
Phone: 1300 738 250
Web: www.chemtools.com.au

[loki42]

I'm happy you're getting good results from it.  I tried it.  I got a free sample.  It wasn't value for money at free.  Worst paste I've used with my setup.  Maybe you need to spend more time mixing it or something.  Maybe i got a faulty batch.  I used to run GC10 and GC18 which were great, currently running Indium SAC305 INDIUM8.9 TYPE 4 which is twice the price but is amazing stuff. Also the documentation from indium is excellent with nice little spread sheet calculators etc.  The docs from okay / chem tools aren't. 

[glenenglish]

Interesting ! yeah I am very happy with it.  what problems did you encounter ?
I've found that its best  at 24 to 25 deg C, that is - not a cool environment... as  like I keep the GC10 at 18-21 deg C during printing.  I found at the cooler temps, FWIW , adhesion wasnt as good, I dunno if that was actually the case, but I got that feeling.

Where are you buying your Indium8.9 ? how do you find your stenciling / paste performance versus temperature ?

[Mangozac]

I'm happy you're getting good results from it.  I tried it.  I got a free sample.  It wasn't value for money at free.  Worst paste I've used with my setup.  Maybe you need to spend more time mixing it or something.  Maybe i got a faulty batch.  I used to run GC10 and GC18 which were great, currently running Indium SAC305 INDIUM8.9 TYPE 4 which is twice the price but is amazing stuff. Also the documentation from indium is excellent with nice little spread sheet calculators etc.  The docs from okay / chem tools aren't.

Something is very very wrong there - did you speak to the guys at Chemtools about it? We use their leaded pastes and the SN100C version of the M8 and both are fantastic. The lead free paste shelf life is a bit shorter than expected but in our experience miles better than anything that had to be shipped in from overseas unrefrigerated.

The Okay website could do with more documentation, but the pastes are just locally mixed version of the AIM products https://aimsolder.com.au/product/sac305-m8-no-clean/.

[loki42]

Interesting ! yeah I am very happy with it.  what problems did you encounter ?
I've found that its best  at 24 to 25 deg C, that is - not a cool environment... as  like I keep the GC10 at 18-21 deg C during printing.  I found at the cooler temps, FWIW , adhesion wasnt as good, I dunno if that was actually the case, but I got that feeling.

Where are you buying your Indium8.9 ? how do you find your stenciling / paste performance versus temperature ?

I'm buying the indium from Hawker Richardson.  I haven't noticed much variation with temperature.  It prints well, cleans well and is easy to deal with.  I tried it in tubs and cartridges.  The aim stuff didn't print well. I tried a few speed / pressure settings and with the 0.4mm pitch stuff paste got stuck in the stencil.  The indium I've had no trouble with.  It might just be more forgiving in my setup, it might need fancier mixing.