TECHNET Archives

June 2017

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Carl Van Wormer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Carl Van Wormer <[log in to unmask]>
Date:
Fri, 2 Jun 2017 13:27:03 +0000
Content-Type:
text/plain
Parts/Attachments:
text/plain (1 lines)
We have a power-control board designed for Pb-Free processing that has many surface-mount components, with parts mounted only on the top side.  Several ICs and transistors are leadless (very low-profile) parts, some with thermal solder pads on the package bottom.  I am requesting their no-clean solder-paste processing because of my fear of their inability to adequately clean a water-clean flux from under these low-profile parts.  I fear a chemistry experiment, since these boards will be placed in an outdoor environment with uncontrolled temperature and humidity.



Question #1: Are my fears about properly cleaning water-clean flux from under low-profile parts justified?





This board has about 20 through-hole capacitors and 5 connectors (100 pins, total).  Our normal assembly house has a water-clean flux Pb-Free wave-solder machine that could be used as a second pass process to add the through-hole parts at a lower cost, possibly reducing the hand-add labor charges.  The wave-solder process would be followed by a cleaning in their new board-wash system.  They do not currently have a method to determine board cleanliness after the cleaning process.  I fear that the nasty flux may flow through holes in the board, finding ways under the low-profile SMD parts on the top of the board, creating another chemistry experiment.



Question #2:  Are my fears about water-clean flux from the wave process flowing to the top side of the board, hiding under the low-profile parts, and performing long-term chemistry experiments valid?



Question #3:  Should I trust a board-washing process that doesn’t have a way to verify the quality of the cleaning?



Question #4:  Are there suggestions to alternative processing methods that I should consider?





Thanks,

Carl





​​​​​



Carl B. Van Wormer, P.E., AE7GD

Senior Hardware Engineer

Cipher Engineering LLC

    21195 NW Evergreen Pkwy Ste 209

    Hillsboro, OR  97124-7167

    503-617-7447x303

    [log in to unmask]<mailto:[log in to unmask]>     http://cipherengineering.com<http://cipherengineering.com/>



This message may contain confidential and/or proprietary information, and is intended for the person/entity to whom it was originally addressed. Any use by others is strictly prohibited.  If I sent this to you by mistake, please be nice and delete it, and then tell me of my mistake so I can send it to the right person.






ATOM RSS1 RSS2