The wave soldering pot temperature needed for SnAgCu solder is between
255-270 C (based on the experiments). The solder pot temperature used with
SnPb is approximately 250 C, which is about 70 degrees over the melting
temperature. With SnAgCu the superheat (= heating over the melting
temperature) is only approximately 40 degrees.

C. Hunt, NPL, Apex 2000 has compared the wetting times of different solders:
with equal superheat the wetting times are similar between SnPb and SnAgCu.
But with SnAgCu even lower superheat works as the experimental test series
has shown.

On the other hand increase on the solder pot temperature can be detrimental
to the flux. For fluxes and for component heat tolerance it is good that
lead free solders does not need so high superheat.

Anybody having an explanation for  this? Why lead free solder does not need
so high superheat (= heating over the melting temperature) as SnPb solder?


  Best regards,

        Elina Havia


--
Ms Elina Havia
Elektroniikan 3K-tehdas
Laitaatsillantie 3
FIN-57170 SAVONLINNA
Finland
tel. +358 15 571 4034
gsm  +358 50 461 5572
fax. +358 15 571 4029

e-mail: [log in to unmask]
http://www.3ktehdas.com



-------------------------------------------------------------------------------Leadfee Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL
Search previous postings at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-------------------------------------------------------------------------------