Recently we have had some disagreements with suppliers over what constitutes dewetting. I would like you opinion. On one recent batch of boards, solder thickness measurements on a single quad pack IC pad ranged from 30 to 600 micro inches. The solder was deposited so that it resembled a volcano top. The edges of the rectangular pad were in the 500-600 micro inch range with a circular like area in the center at 38 micro inches. This type of irregular coating was seen throughout the board. It is my opinion that a solder coating thickness on a pad less than 50 micro inches indicates dewetting. It is also my opinion that lower thicknesses (and hence poor soldrability from dewettted pads) leads to long term degradation problems in storage and little Intermetallic formation. There is some data from HUG *Hot Air Levelling User Group" that the cutoff number might be closer to 25 microinches (Circuit Tree Oct 20 artcicle by Furrow and Fellman) I am not considering ground planes. The most likely cause would be inadequate cleaning of the copper prior to HASL and/or a HASL flux that contains a high (greater than 5%) concentration of acid (hydrochloric or hydrobromic). we accep to IPC A610, Class 3 requirements for space launch system use. Any feedback? --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 847-509-9700 ext.5315 -----------------------------------------------------