Good morning Luan, It sounds like a design issue where the SMT chip pads directly connected to the PTH next to it are sent into reflow during contact with the molten solder from the selective solder machine. Attempting to coat the SMT chip solder joints with temporary soldermask does not work, because underneath the maskant the solder is still able to go into reflow as a result of direct contact with the molten solder from the PTH part and the surrounding heat through the board itself. Solder can easily flow away from the chip cap solder joints underneath the temporary solder mask. It is possible that the only way to fix this would be a design change. Another possibility would be to identify the particular PTH parts that cause this to happen and hand solder those. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Luan Nguyen Sent: Sunday, June 26, 2011 10:18 PM To: [log in to unmask] Subject: [TN] Chip insufficient by Selective soldering Dear TechNet, We have been facing the insufficient solder at Chips from Selective soldering. When we solder Through hole components, solder volume of Chip pads next to PTH component is reduced, cut-down and these chips are insufficient solder. Although we have applied solder stop material (Pn: 700-1603-000-V, Wondermask 2207-5G, Techspray Solder Stop) to cover these chips but the problem have been happening. We understood that temperature to solder PTH component caused to this problem but we don't know what action for them. Would you please help us to understand the principle of this insufficient and have any related documents or any advice. We thank advance! Luan Nguyen. *************************** Nguyen Hoang Luan QA Supervisor - IPC Trainer Spartronics VietNam Co, Ltd. No.3, Street No.6, VSIP Th An Dist., BDuong Prov., VN Tel: (84-650) 784 890 Fax: (84-650) 784 891 Mobile: 090.3.667448 Email: [log in to unmask] *************************** ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 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 For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 16.0 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 For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------