I have started to make my reflow profile measurement tools by combining the
single side board and the double sided board together.
The advantage is that I get to measure the coldest connection (largest mass
on the leading edge of the double sided board) and the warmest connection
(smallest passive on the trailing edge of the single sided board)
Reducing the set up time at reflow is accomplished because you don't have
any oven changeover between the two sides of the board. The same profile
works for both sides.
Having said that, I should mention that I typically have ABAB panels so
half my BGAs see two reflows and the other half only one reflow.
Bright and shiny solder has not been a requirement for quite a
while.....especially since most have gotten rid of nitrogen atmosphere
reflow ovens and have accepted the oxidation that occurs the second time
through.
Phil
At 04:27 PM 3/28/2007 -0400, Dehoyos, Ramon wrote:
>
>
> You are going to try out something that is reverse from what
>ordinarily is done. A complete reflow has been accomplished on the big
>part side and you are trying to have those parts upside down on the
>second run ( glue them so they do not fall down, an extra step ). The
>board goes through chip shooter and places the small parts. A lower temp
>profile will reflow the small parts and barely reflow the first side.
>Try the concept on a scrap board. It might work.
> Regards,
> Ramon
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan
>Sent: Wednesday, March 28, 2007 4:13 PM
>To: [log in to unmask]
>Subject: Re: [TN] Double sided reflow
>
>Phil,
>
>you are right if we consider a somewhat balanced top-bottom component
>distribution.
>
>What I am talking about is the case where the heavy stuf, BGAs,
>heatsinks, transformers, etc, are all on the first side that is
>soldered, whereas on the second side there are small discretes only,
>e.g. 0603 and 1206. In this case you can solder the discretes at lower
>temperatures, but these temperatures are not enough to properly reflow
>the joints of the first side.
>
>Don't ask me why would I do such a stupid thing, reflow the havily
>loaded side before the light one. I am simply trying to brainstorm on
>how to reduce setup times at the reflow oven. And the basic rule of
>brainstorming says that nothing is stupid a priori.
>
>Thanks,
>
>Ioan
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]]On Behalf Of Phillip Bavaro
>Sent: Wednesday, March 28, 2007 3:45 PM
>To: [log in to unmask]
>Subject: Re: [TN] Double sided reflow
>
>
>Ioan,
>
>Someone can't see the forest because the trees are in the way....lol.
>
>The second side reflow is actually more thermally demanding because it
>has to account for both sides of the board with respect to mass. Set
>your reflow profile up for the double sided reflow only and use it for
>both sides.
>
>Phil
>
>At 03:42 PM 3/27/2007 -0400, Tempea, Ioan wrote:
> >Dear colleagues,
> >
> >let's take a board with SMT on both sides. Let's say that for
> >particular reasons we have to solder the more thermally demanding side
>first.
> >
> >The question is: when reflowing the second side, the one that requires
> >lower temps because the components are less demanding, may the reflow
> >recipe be colder? Will this affect the other side, that will reflow
> >again, but at lower temps and for not as long? I mean the IMC is
> >already formed; is there anything else that could go wrong?
> >
> >Or, to generalize, a PCB with SMT parts that were properly reflowed
> >once, can it be reflowed again at lower temperatures, without adverse
> >effects on the metallurgy of the joints?
> >
> >Thanks for your help,
> >
> >Ioan
> >
> >---------------------------------------------------
> >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
-----------------------------------------------------
|
