AN AIM VIDEO SERIES

Line-Down

Learn how to overcome your electronic assembly challenges in AIM’s Monthly web series “Line-Down”. AIM’s technical experts answer our customers’ defect-related questions by providing process tips, problem solving tools and suggesting the most appropriate materials to help you minimize or eliminate common soldering defects.

Questions from the Line

and answers from an AIM technical expert.

Line-Down Episodes

QUESTION: We recently switched to a different SAC305 solder supplier to save costs, but we’ve started running into issues with our wave soldering process. We’re seeing inconsistent soldering, an increase in bridging, and we’ve had to scrap more boards than usual. What’s going on?

QUESTION: We’re currently qualifying a new high reliability paste that should meet all of our requirements for thermal cycling, drop shock and more, but we’re having a lot of problems with voiding. What’s going on?

QUESTION: We keep having problems with paste not completely melting on some of our components during reflow. What’s causing this and how do we fix it?

QUESTION: You have mentioned before that once a solder paste jar is opened; it can’t be re-refrigerated. Why is this? How long can this paste last outside of refrigeration?

QUESTION: I need to use rectangular stencil apertures in order to get the right volume of solder paste on my boards within a tight space, but I’m having trouble with the paste sticking to the corners and not releasing. What should I do?

QUESTION: “We have a new job coming in where we need to print boards with components as small as 01005s. Until now, we’ve only used Type 4 paste, but are wondering if we should switch to Type 4.5 or Type 5 for this application.”

QUESTION: We are having to scrap a lot of boards after wave soldering because the solder mask keeps delaminating and crazing. Why is this happening and what can we do about it?

QUESTION: We are switching suppliers for our SN100C bar solder. Is it ok to combine bar from our old supplier with bar from our new supplier in the solder pot?

QUESTION: We are having a lot of issues with QFN voiding. Our results are always at or just above the customer-specified limits. We have tried switching pastes and adjusting reflow profiles to no avail. What else can we try?

QUESTION: In order to simplify our production process, which requires soldering both SMT and through-hole components, we’ve been using the Pin in Paste/Intrusive Reflow technique in which we print paste over the through-holes at the same time we print paste for the surface components and reflow everything all at once. However, we keep having reliability issues with these through hole components. Any ideas why?

QUESTION: We’ve been having some particularly concerning field failures that we think are resulting from electrochemical contamination. Any idea what may be causing it?

QUESTION: We’ve been having repeated issues with bridging in our solder printing process. This is especially problematic in our dense PCB layouts. Can you help?

QUESTION: In our recent PCB assembly, we have a significant number of bottom-terminated components. We’ve been noticing some unusual performance issues across the board, which we suspect may be linked to the no clean solder residue under these BTCs.

QUESTION: We’re having solderability issues due to problematic components. Unfortunately, we have no choice but to use the components provided, but is there anything we can do on the solder side to improve outcomes?

QUESTION: My company is experiencing a lot of non wet open defects that we’re attributing to warpage after reflow when soldering large processors. What can we do about this?

QUESTION: Why are there missing components on my PCBs after the reflow process?

QUESTION: My second shift operator forgot to take out the solder paste out before the end of his shift, so the paste still cold. What do I do?

QUESTION: I need type 5 solder paste, but I having problems to get it from my distributor with high minimum order quantities in high cost, Do I have other options?

QUESTION: What materials should I use when reworking low-temperature solder paste?

QUESTION: Our inspectors are finding solder beads around our chip components, what should I do?

QUESTION: Can your BTC ground pad aperture design reduce voiding?

QUESTION: I am seeing Head-In-Pillow defects on my boards. How can I reduce this?

QUESTION: How much dross can accumulate on the surface of my wave solder pot before it obstructs my process?

QUESTION: One of our sister plants is using an automated mixer to reduce the amount of time it takes to prepare paste. Will this help me too?

QUESTION: I am having a BTC voiding problem. I tried modifying my stencil apertures and adjusting my reflow profile and nothing seemed to work. Can you help?

QUESTION: If I find paste in the refrigerator which has been opened, can I use it in production? 

QUESTION: I have old paste laying around, can I mix it with my new paste and use it in production?

QUESTION: My second shift operator forgot to take solder paste out before the end of the shift, the paste that I want to use is still cold, what do I do?

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