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Solder Pot Maintenance and Dross Removal

Question: We found an article online about solder pot maintenance and the removal of dross, specifically there is an interest to us in the “changing bar solder” Section. Does turning up the solder pot too high cause impurities to collect on parts? Can you comment on this?

What’s with the expiration dates on solder paste or wire?

Question: We all have from time to time had solder, be it in paste or wire form, sitting on shelves for what seems like years. I know there are all types of variables related to its’ longevity, but given this, what’s really going on with the expiration dates and are there tests you can perform to validate or extend this period?

Accept or Reject: Solder Contacting Component Bodies

Question: We are having a discussion about whether or not solder can touch a component body; in particular, we have a plastic SMT component where the solder has wicked up to the body on the legs. Sections are shown below. Is this condition acceptable under any circumstances, or is it always a reject in all three classes?

Issues of Burnt Flux on Class 3 PCB Assemblies

Question: I have always had in the back of my head that burnt flux is a defect for all class 3 assemblies. Upon further review I have not been able to identify the specific section of the IPC-A-610F standard which identifies burnt flux as an acceptable or defect condition.

Gold Removal Issues with Hollow Cup Connectors

Question: We are having a hard time with the removal of gold from hollow cup connectors. Using lead free solder, we are wicking the solder out with braid, but what is happening is that the pins are getting overheated and coming loose from the connector. Are there other methods we could explore?

Acceptability of Conformal Coating Bubbles

Question: We have some PCB cards that are flooded with champagne size encapsulated bubbles. While no single bubble bridges between conductors there are numerous small bubbles similar to Figure 10-131 below, None have popped, as they are all encapsulated. Is Figure 10-131 a Defect Photo?

SolderTips: Avoiding the Creation of Splices Via Wire Twisting

Question: The IPC lists different splices for wires including wrap, hook, mesh, and lap. We have all seen wires spliced together by twisting the two wires together forming a gentle twist before soldering. This splice would not have the physical strength of a wrap or hook splice, but it seems like it would offer at least the same strength as a lap splice with less aggravation, since the splice would stay in place during the soldering process. Why does the IPC not recommend creating this type of splice?

SolderTips: Solderability Issues with Nickle Plated Surfaces

Question: We are working with components with leads of tin/lead over nickel. After the manufacturing processes, some of the pins are exhibiting what appears to be flaking plating, leaving behind unsolderable surfaces. They will re-tin with flux, but reappear following steam-aging. Is this something you have encountered before?

SolderTips: Gold Removal and Wave Soldering vs Hand Soldering

Question: Regarding gold removal requirement under Section 4.5.1 of J-STD-001, it allows: “A double tinning process or dynamic solder wave may be used for gold removal prior to mounting the component on the assembly”…

SolderTips: Soldering With Butane Soldering Irons

Question: Can Butane solder irons be used for soldering coax cable (pin on center conductor) or any other type of cabling? We are concerned about the temperature as compared to regular soldering stations.

SolderTips: Issues With Incomplete Solder Reflow in Production

Question: We have some PCB assemblies that show incomplete solder flow due to signs of flux exhaustion.

SolderTips: Printed Circuit Board Bow and Twist Showing Up

Question: We have recently started to see board flexing in one of our circuit board assemblies. This assembly has a 40mm PoP BGA component on it with an integrated heat sink.

SolderTips: Issues With Incomplete Solder Reflow in Production

Question: We have some PCB assemblies that show incomplete solder flow due to signs of flux exhaustion.

SolderTips: Soldering Iron Calibration – Do You Really Have To?

Question: To calibrate or not to calibrate, that is the question. We just purchased new soldering stations and were told that they do not require calibration. While we think that all tooling requires some calibration over time, what am I required to do?

Rechecking Thermal Profiles

Question: Is it necessary to replicate the thermal profiling process during long term mass production of products?

Solder Paste Shelf Life and Testing

Question: We have some solder paste that has been in a sealed box at 4 degree Celsius for more than 8 months. The shelf life is 6 months. Can it be used without an issues?