Check with your component supplier, many were using Nylon 6/6 which has
a melting point of 255C, some have changed to Nylon 4/6 which melts at
290 C, would/ should be a new Part Number and more robust in higher temp
pre-heaters.
Rick Smith
Senior Product/ Component Engineer
Phone: (512)652-3544
Fax: (512)652-3545
Cell: (512)299-6925
Email: [log in to unmask]
ClearCube Technology, Inc
8834 Capital of Texas Hwy N
Austin, TX 78759
www.clearcube.com
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Joel Mearig
Sent: Wednesday, October 12, 2005 2:03 PM
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
I am using a selective soldering system and I still have concerns with
the
low temp through-hole parts. Due to the increased solder pot
temperature,
when using lead-free solder, the plastic of the connector will get
hotter
then in a standard Pb/Sn process. I have actually seen the plastic melt
around the pin during the selective soldering process.
I am in the process of changing my connector (and other through-hole)
parts
to specify a higher temperature plastic that will work with my Pb-free
process.
I have noticed that a few suppliers (Teka in particular) are supplying
parts
that will withstand SMT reflow oven processes.
Joel Mearig
Delta Tau Data Systems, Inc.
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Gilbert, Doug
Sent: Wednesday, October 12, 2005 11:51 AM
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
TI Doug,
Since TI does not rate the temperature max of their Pb-free TO-92
or dip packages ( or other thru hole packages ) does this mean TI
feels they never get hot enough to be a problem with wave soldering?
How hot do they get? Thanks.
Doug
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of Romm, Doug
Sent: Wednesday, October 12, 2005 11:44 AM
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
Dave,
For TI SLL (Standard Linear and Logic) Products here is our status on
TO-92 packages:
* Our course our historical finish is SnPb.
* However, we do offer Sn finish (Pb-free) as an option on the TO-92
package. To get the Pb-free version of TI TO-92 devices the customer
needs to order with a Pb-free suffix.
* No, TO-92 devices are not rated per the J-STD-020C. TI through-hole
packages that are built with a Pb-free finish are however identified as
"Pb-free" on the packing labels and web search tools.
Best regards,
Doug Romm
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Wednesday, October 12, 2005 1:38 PM
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
Hi Doug! Do you know what the surface finish of TO-3 and TO-92
components
is?
Dave Hillman
Rockwell Collins
[log in to unmask]
"Gilbert, Doug"
<Doug.Gilbert@CAX
.USA.XEROX.COM>
To
Sent by: Leadfree [log in to unmask]
<[log in to unmask]
cc
>
Subject
Re: [LF] Leadfree Processing temp
10/12/2005 01:32 requirement
PM
Please respond to
"(Leadfree
Electronics
Assembly Forum)"
<[log in to unmask]
>; Please respond
to
"Gilbert, Doug"
<Doug.Gilbert@CAX
.USA.XEROX.COM>
RoHS warriors...
While talking about temperature requirement for Pb-free, I was asked
why semiconductor vendors are not temp rating their Pb-free DIP
packages. I
believe these are considered 'not MSD' but do they never see 260 deg.C?
I am not knowledgeable in assembly processing in detail hence my
questions.
For mixed assembly I think the SMD parts are reflowed first then any
thru-hold parts are wave soldered. The parts don't have to withstand
high temp since only the leads are exposed?
Another mystery. I know that BGA type parts are not backward
compatible.
But ON Semi just issued a PCN saying their Pb-free TO-3 and TO-92
packages
are also not backward and should be used for Pb-free soldering only.
Why would that be?
Thanks,
Doug
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]]On Behalf Of James, Chris
Sent: Wednesday, October 12, 2005 6:55 AM
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
Only to add that yes it is not simple.............
If you have an old 4 zone oven you might have probs and need more zones.
It depends on component mix on the board to a certain extent - if you
have some parts with large thermal mass then all the tiddlers are going
to get hotter!
Look carefully at specs on electrolytics (these can distort if over
cooked) and Leds where the lens will discolour or dull.
You certainly need to be looking for RoHS process compliant parts with
peak reflows of at least 240 through to 260C.
All this also has an effect on MSL rating requirements so storage
considerations may need to change.
Look for parts meeting JSTD-020C.
Regards,
Chris
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Smith, Rick
Sent: 12 October 2005 14:39
To: [log in to unmask]
Subject: Re: [LF] Leadfree Processing temp requirement
Ken,
I'm going to open a can of worms with this one, and I'm sure will get
plenty of responses.
The target peak for SAC305 is 253 C for most applications. (245 C is too
cool).
You should be above 217 C for 45 to 90 sec.
But 217 C is not the temp you should worry about, it's really somewhere
around 235/7 C which is where the solder melts to other metals, (wetting
temp). If you are not over the wetting temp long enough you will
experience poor wetting, especially with OSP, where you need to be near
the "longer" end. You should stay over 235 C for 30 to 45 seconds.
Now the kicker here is, that if your oven has poor thermal capacity, you
can see a temp difference across the board of as much as 30 to 35
degrees C if you are soldering a component like the 775 Socket T and
trying to get the underside to melt.
That means other solder joint temps in a bad oven could hit 285 C,
(don't ask about the component body) which is unacceptable for most
components that are rated at 260 C.
If your oven cannot maintain at least +/- 10 degrees C across the PCB on
your heaviest boards/components (+/- 5 degrees C on regular LF product)
you should replace it. 10 years ago I would have said +/- 3 degrees C,
but I have been soldering some weird stuff lately, :<)
-----Original Message-----
From: Leadfree [mailto:[log in to unmask]] On Behalf Of Kanaiyalal Patel
Sent: Tuesday, October 11, 2005 7:10 PM
To: [log in to unmask]
Subject: [LF] Leadfree Processing temp requirement
All,
Has IPC modified the document related to component spec from process
point of view such as reflow and wave. I forgot the document number.
This document is being used by supplier/manufacturer to make parts that
can withstand needed Leadfree reflow/wave temperature. Few of my
suppliers' parts are rated around 240c max and I think that is too low
for leadfree process. Can someone provide the temp numbers withour
buying a IPC spec for urgent requirements?
Any help will be appreciated.
re,
ken Patel
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