If you try to touch up from the top side, you could create a void within the plated thru hole. I would suggest you apply flux, desolder the connection and then solder the joint properly and preferably with a direct power soldering iron, this will ensure sufficient heating to reflow the entire connection from top to bottom.
Edward Zamborsky
Regional Sales Manager, OK International Inc.
Ed Zamborsky is a Regional Sales & Technical Support Manager for Thermaltronics, located in New York. His position requires frequent customer visits throughout North America and the Caribbean and his position encompasses not only sales but the role of trainer and master applications engineer for all of Thermaltronics products. His expertise includes such specialties as hand soldering, convection and conduction reflow techniques, array rework, fluid dispensing equipment, and fume extraction. Ed has authored many articles and has presented many papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead-Free Hand Soldering, High Thermal Demand Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
IPC has an entire rework standard which will directly specify the proper method of PTH rework. In most cases, you will address the solder joint from the solder side with the iron touching the lead/pad simultaneously and for the minimum amount of time. The solder wire, will be introduced from the opposite side. Rework and what you are accomplishing, is specific by part and iron technology. IPC 7711 is your best source to decipher your issue and approach.
Rodney Miller
Capital Equipment Operations Manager, Specialty Coating Systems
Rodney is currently Operations manager at SCS coatings, Global Leader in Parylene and Liquid Coating equipment. Rodney applies his BS in Computer Integrated Manufacturing from Purdue University, along with 20+ years of Electronic manufacturing and Equipment Assembly, to direct the Equipment business at SCS Coatings. "We provide unique, value added coating equipment solutions for our customers". Including conformal, spin and Parylene coating expertise.
Apart from using a solder iron and solder wire, a solder preform can be used to rework the through-hole joint. In this case, donut preform (that comes prefluxed) can be placed on top of the pins. A heat gun is used to melt the preforms for complete hole fill. The manual component is removed;eliminates the fluxing step; the solder volume is consistent from pin-to-pin; and all preforms can be melted in 1 shot.
Karthik Vijay
Technical Manager - Europe, Indium Corp.
Currently with Indium Corporation and responsible for technology programs and technical support for customers in Europe. Over 15 yrs experience in SMT, Power, Thermal & Semiconductor Applications. Masters Degree in Industrial Engg, State University of New York-Binghamton.
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