Hi Michael: HASL is much less expensive and less time consuming
to plate. Selective solder reflow is used by very few companies that are
not ready to change the way things were made long time ago just because
it works.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Barmuta, Michael
Sent: Tuesday, May 08, 2007 11:37 AM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Hi Ramon: As I said "conventionally built" fused Sn/PB boards have the
fused Sn/Pb on the circuitry under the mask. This is how standard fused
Sn/Pb board were built in the 60's, 70's and beyond. A more
unconventional approach is what you are referring to. Boards can be
built this way but are more complicated and expensive due to the
additional processing. However it will take care of the melting metals
under the mask condition.
If you are going to go to all the trouble of maintaining a Sn/Pb plating
line, plating Sn/Pb, selectively masking, selectively stripping the
plating, stripping the masking, fusing, washing, cleaning the exposed
Cu, applying soldermask, etc, why not just build a SMOBC/HASL board.
It's much simpler.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett WA
425-446-6076
-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Tuesday, May 08, 2007 7:37 AM
To: TechNet E-Mail Forum; Barmuta, Michael
Subject: RE: [TN] What is the difference between Fused SnPb and HASL?
Michael:
Traces or other geometries that are not to be soldered
and are going to be under the solder mask do not need to have fused
solder at all, just pure cleaned, bright copper. If solder is left over
the traces that are under the solder mask, it will melt when board is
reflowed or wave soldered as you said. That would not be a good thing.
Solder mask should adhere to the copper well and not be affected by
process temps much at all.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Barmuta, Michael
Sent: Tuesday, May 08, 2007 10:21 AM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Wee: A fused Sn/Pb board is normally covered by soldermask. If not you
could obviously have a real mess at wavesolder.
The problem with a conventionally built fused Sn/Pb board i.e. circuitry
is fused Sn/Pb, is that during reflow and/or wavesolder the Sn/Pb melts
under the mask. This can cause adhesion failure of the soldermask to the
Sn/Pb. It is especially true for larger features, ground planes, etc. If
the board is then washed the condition can be aggravated by the
chemistry and spray impingement resulting in additional loss mask or
entrapment of wash residues.
This was one of the drivers for going to a SMOBC style of construction,
no melting metal under the mask.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett WA
425-446-6076
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lum Wee Mei
Sent: Monday, May 07, 2007 5:37 PM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Thanks for the responds. From what I have gathered, fused SnPb can also
have solder mask on them. My initial understanding or interpretation was
that HASL finish is for SMOBC while fused SnPb finish is for board
without solder mask.
Regards,
Wee Mei
________________________________
From: TechNet on behalf of Dehoyos, Ramon
Sent: Mon 5/7/2007 10:15 PM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Wayne:
Mostly copper with SnPb over it on some slivers. Pure copper
from geometries such as traces and with SnPb such as pads. The slivers
can be very small or very large. It depends on how it was removed. Large
by hand and small by pumice spray. If they break off and wash away, no
problem. If they partially break off and stay, they may shorten
geometries. Other name for them is inclusions.
Ramon
>>>>> --------------- <<<<< The edges at the top will break
off as slivers.
| |
| |
| |
| |
-------
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Monday, May 07, 2007 9:53 AM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Ramon-
But it was the SnPb which had slivers, and if that is chemically etched
away, then what are the slivers made from?
Wayne
>>> [log in to unmask] 5/7/2007 9:16 am >>>
Wayne:
That is affirmative. SnPb is removed from everywhere except the
pads, lands and anything else that needs solder over the top of copper.
At this time bare copper is oxidized and needs to be cleaned by hand or
spray so that SMOBC can adhere to it and slivers brake off.
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Monday, May 07, 2007 8:56 AM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Ramon-
What is it that needs mechanical removal? The oxidation of the copper
traces due to selective SnPb removal?
Wayne
>>> [log in to unmask] 5/7/2007 8:46 am >>>
Fused solder is more expensive and it takes about 5 more steps.
When the SnPb is used as etch resist, as Wayne mentions, to pattern the
outer layers and plate the pads and lands, the etching is not vertical
so there is some underetching.
slivers are formed at the top edge of the geometries. Later the traces
have the SnPb taken off. So prior to having the solder mask applied,
the copper traces are dull due to oxidation from etching the SnPb off
which needs to be mechanically removed, leaving possible inclusions
partially broken off. It can be a messy situation. Pads and lands are
left with the solder over them which is later on fused by reflow oven.
Thus the name fused solder. Most companies use HASL very few use Fused
solder.
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Monday, May 07, 2007 8:14 AM
To: [log in to unmask]
Subject: Re: [TN] What is the difference between Fused SnPb and HASL?
Werner is quite correct but only mentioned the metallurgy, not the
ramifications for processing.
HASL is a quite obnoxious process in terms of board stress during
application, but most non-aggressive board constructs can handle it:
The panel is plunged into a vat of molten solder and then withdrawn
while being blown off with very hot air. The deposits are lumpy, and
start giving problems for smaller parts.
Fused SnPb is just convection heated to slightly above the melting
point--no thermal shock. Also the deposits are extremely even, so very
fine pitch work is no problem. However, the normal way of achieving
Fused SnPb is to use the plated SnPb for the final etch resist. This
means that if you have a board with a solder mask, then the SnPb will be
under the mask, which will greatly reduce its effectiveness.
Wayne Thayer
>>> [log in to unmask] 5/6/2007 9:39 pm >>>
Hello,
I come across QML vendors that state their finish system : HASL, Fused
Solder, while some only states : HASL. I know that HASL stands for "Hot
Air Solder Leveling", what then is fused solder? There must be some
difference between them - what are they?
Thanks and regards,
Wee Mei
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing
per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
This message (including any attachments) contains confidential and/or
proprietary information intended only for the addressee.
Any unauthorized disclosure, copying, distribution or reliance on the
contents of this information is strictly prohibited and may constitute a
violation of law. If you are not the intended recipient, please notify
the sender immediately by responding to this e-mail, and delete the
message from your system. If you have any questions about this e-mail
please notify the sender immediately.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0 To
unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or
(re-start) delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the
posts: send e-mail to [log in to unmask]: SET Technet Digest Search the
archives of previous posts at: http://listserv.ipc.org/archives Please
visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
This message (including any attachments) contains confidential
and/or proprietary information intended only for the addressee.
Any unauthorized disclosure, copying, distribution or reliance on
the contents of this information is strictly prohibited and may
constitute a violation of law. If you are not the intended
recipient, please notify the sender immediately by responding to
this e-mail, and delete the message from your system. If you
have any questions about this e-mail please notify the sender
immediately.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
