Richard, Im thinking what you are describing is probably related more to
the "process-window" than anything else. If you have selected the right
materials, received and prep'd (bake as applicable) all of your
components properly then the wetting should be good as long as you are
able to hit the "wetting" temperature (which is 230C ~ 235C range
depending on which alloy you select) for a sufficient amount of time to
allow the solder to flow to the pads/and component leads.
If you are one of those un-blessed engineers to be stuck with equipment
that has marginal thermal capacity, then you will probably not be able
to hit the wetting temperature without significantly overshooting the
peak temperature ratings on your components. If this is the case, your
management needs to send you out to buy new ovens, (not to mention
possibly some rework equipment).
We are seeing an increase in fails, lots are related to component heat
issues, but have not determined yet if any are related to whiskers, by
the time we think of this the rework is done. Have you seen any of these
whisker issues?
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, July 12, 2006 9:28 AM
To: [log in to unmask]
Subject: Re: [LF] How's RoHS doing?
Speaking seriously, though, in my consulting I am seeing a lot of open
solder defects where SMT leads on connectors and SMT I.C.s are sitting
on top of a molten dome of solder, but no wetting took place on the
leads themselves. It is obvious to me that the resistance to wetting of
some components is more obvious with the lead-free solder. It is on many
components, on many different types of boards, at several different
companies. I do not fully understand why this is happening. Does anyone
else see this or understand the cause?
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
Sent: Wednesday, July 12, 2006 9:17 AM
To: [log in to unmask]
Subject: [LF] How's RoHS doing?
Dear colleagues,
any news on the implementation of RoHS? We're already 12 days into it
and I hear no crying in the forum.
Did anybody clash with the RoHS police? Are they active, any good or bad
stories?
Thanks,
Ioan
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