| Ask the Experts | ||||||
|
||||||
|
November 24, 2008
Solder Bump QFN's for Rework Is it an acceptable practice to "solder bump" pads when replacing a QFN or must you always apply solder paste? D.W. |
||||||
| Expert Panel Responses | ||||||
|
It is nearly impossible to accurately "solder bump" these components back into place on your PCB. Sure you might have one operator who can achieve satisfactory results, but it will never be reliable enough to meet your quality requirements. For best and repeatable results, you need to remove all residual solder from the site, be sure to clean the site so there are no flux residues. Then print the new solder paste directly onto the pads of the component, ensuring the correct volume for the central grounding pad (too much and the component will float during reflow), pick the component from the paste printing plate with your rework system, align it to the pads on the PCB and place the component. Reflow with the correct thermal profile.
Regional Sales Manager OK International Inc. Mr. Zamborsky serves as one of OK's technology advisers to the Product Development group. Ed has authored articles and papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead Free Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
|
||||||
| Submit A Comment | ||||||
|
Free Newsletter Subscription
Circuitnet is built for professionals who bear the responsibility of looking ahead, imagining the future, and preparing for it. Insert Your Email Address |