Good day, Luan
Here are some things to try.
If you can, try pre-heating the assembly using either a small oven or a
hot plate just prior to soldering. Make sure the operator wears some
type of gloves to protect their hands when handling to hot assemblies.
Try pre-heating to about 90 deg. C to 110 deg. C. Pre-tin the component
leads if necessary to aid in the wetting. 
I suspect you are not getting topside fillets only because of the mass
of the assembly, so making sure the assembly is pre-heated while
soldering should fix the issue. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Luan Nguyen
Sent: Tuesday, August 26, 2008 9:27 PM
To: [log in to unmask]
Subject: [TN] solder vertical fill on thermal pad

Dear All,
we are having a problem about hand soldering (lead-free) for some PTH
parts mounted on thermal pad. Solder vertical fill is difficult to up
75%. Can you help us some conditions and technics related for this
problem. 
Thanks

***************************
Nguyen Hoang Luan
QC&Training Supervisor
Spartronics VietNam Co, Ltd.
No.3, Street No.6, VSIP
Th An Dist., BDuong Prov., VN
Tel: (84-650) 784 890
Fax: (84-650) 784 891
Mobile: 090.3.667448
Email: [log in to unmask]
***************************

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