Dear Werner:
XIEXIE! 谢谢！
I have checked all the documentations in my company and finally got this
value, the recommended hole roughness in IPC-DR-572A is 25 um (1 mil), and
it is not a non-mandatory value. my products are usual memory modules, the
hole diameter is 9.8mil and thickness is around 1 mm, the AVG copper
thickness is 0.8mil, so the roughness is ok regarding to my products.
Thanks!
Winning
-----邮件原件-----
发件人: TechNet [mailto:[log in to unmask]] 代表 Werner Engelmaier /*
发送时间: 2009年5月18日 23:21
收件人: [log in to unmask]
主题: Re: [TN] 答复: [TN] Rohs SMT parts and shelf lif e
Nee hao Winning,
Sorry, I do not have IPC-DR-572; however, you can directly get it from
www.ipc.org.
More importantly, you need to decide for your product what you need from a
technical perspective---that depends on hole diameter, PCB thickness, Cu
plating thickness, assembly proces(ses), etc.
Werner
-----Original Message-----
From: ee <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, 18 May 2009 10:22 am
Subject: [TN] 答复: [TN] Rohs SMT parts and shelf life
Hello Werner:
I am wining from China, and need your help for below issue.
I knew you via my trainer on my IPC training course, and you are always
help others in this forum, now, I meet a problem and need your help to
solve, could you send me a softcopy of IPC-DR-572 which contains the
regulations for hole roughness(1 mil).
Thanks
Winning
-----邮件原件-----
发件人: TechNet [mailto:[log in to unmask]] 代表 Werner Engelmaier /*
发送时间: 2009年5月18日 19:43
收件人: [log in to unmask]
主题: Re: [TN] Rohs SMT parts and shelf life
Hi John,
There are no guarantees, beyond a date code, in either buying direct versus
distributors.
Werner
-----Original Message-----
From: [log in to unmask]
To: TechNet E-Mail Forum <[log in to unmask]>; [log in to unmask]
Sent: Sun, 17 May 2009 8:18 pm
Subject: Re: [TN]
Rohs SMT parts and shelf life
Thanks. did you have any ideas about the shelf life of the components and
buying direct versus distributors for the reasons listed?
----- Original Message -----
From: "Werner Engelmaier /*" <[log in to unmask]>
To: [log in to unmask]
Sent: Saturday, May 9, 2009 3:07:07 PM GMT -05:00 US/Canada Eastern
Subject: Re: [TN] Rohs SMT parts and shelf life
?John,
What needs to be always understood is the fact that you do NOT solder to any
of the surface finishes like tin, silver, gold palladium, etc. but to the
metal these surface finishes are protecting.
So, the profiles need to be adjusted for the Liquidus temperature of the
solder alloy and to a lesser extent to the the solubility of the metal
soldered to in the solder. The latter means that if you solder to nickel
[ENIG, Alloy 42] you may need to run a somewhat higher peak reflow T.
Werner
?
?
-----Original Message-----
From: Bev Christian <[log in to unmask]>
To: [log in to unmask]
Sent: Sat, 9 May 2009 11:30 am
Subject: Re: [TN] Rohs SMT parts and shelf life
John,
I had a little trouble understanding part of your e-mail, but I think I got
the
gist of it. No, you do not need a different reflow profile for good tin
parts
any more than you need a different profile for silver, gold or palladium
finishe
d components. You either have oxidized parts, dirty parts, bad paste,
wonky profile. Other TechNetters will have other suggestions I'm sure.
Bev
RIM
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Sat May 09 11:03:43 2009
Subject: [TN] Rohs SMT parts and shelf life
My concern is that when purchasing buys directly from the manufacturer use
know
the date of manufacture.
When you buy from a component distributor or when you have to build from
consigned parts supplied by the customer you don't know the date of
manufacture
and have no idea how the parts were stored and repackaged.
We?would like?to generate an Iso procedure relative to this issue and would
like
some advice.
What I'm seeing are circuits boards that have been reflowing perfectly for?
quite some time are now built with more and more components that are plated
with
100% tin. Soldering to tin with a eutectic?OA solder paste shouldn't cause a
problem if the?leads or termination on QFNs,?a bigger problem?are not
oxidized
or contaminated.
I checked on the internet to see if?you need to adjust the profile when
soldering to tin coated parts with? eutectic solder but found nothing. You
get
two?sets of profile families, one for eutectic and one for?Pb-free. Nothing
for
a mix so I'm leaning toward a contamination or age problem. ??
Thanks for any help you can
offer.
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