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Recent Ask the Experts Questions
May 21, 2019
Baking Concerns for Stacked Trays of Components
When we are baking multiple trays of parts stacked on top of each other in our oven, will this lessen the effect of baking on the components in the middle trays. Do the trays need to be separated? We bake our components according to IPC specifications.
May 20, 2019
Tough Hand Soldering Problem
I work in an auto glass factory and we're havingproblems soldering the defrost cable wire tothe windshield grid pattern. I think it has to do with factory temperature as it is very hot over100 degrees F.
It is also extremely humid with levels reaching close to 100percent. My bosses keep blowing chillers on the glass but with little effect. What can we do to improve the solder connections.
May 17, 2019
OA Flux Turning Blue
We use Organic Acid (OA) Flux with our Selective wave and Wave Soldering operations. I have noticed after some period of time the OA flux turns blue. What might be the reason behind this? The flux isn't expired.
May 16, 2019
Solder Paste Viscosity
What key factors affect solder paste viscosity? Assuming we only focus on the powder, will more fine powders increase the paste viscosity or the reverse?
May 15, 2019
Application Using No-Clean and Water Soluble Fluxes
If we use a no-clean solder paste for SMT, is it acceptable to use a water-soluble solder wire for subsequent processes (soldering through hole components by hand, not touching up the original SMT)?
We have some difficult assemblies where water-soluble wire just works better for hole fill.
May 14, 2019
EMI Shield Reflow Soldering Techniques
When reflow soldering a RF shield frame to a PCB, what techniques can be used to keep the frame perfectly aligned on its footprint?
Through hole pins can cause signal leakage, could a tooling pallet be used without significantly affecting the reflow profile?
After reflow, what effective techniques can be used to ensure consistent solder coverage around the entire perimeter of the RF shield frame?
May 13, 2019
Shelf Life Limit for Soldering Old Components
We are contract EMS provider and we have some customers with restrictions on how old electronic components can be when soldered. Some customers allow up to 3 years, some allow up to 5 years after the date of manufacture.
Is there a guideline by IPC or other sources that we can follow based on the class of the PCB assembly?
May 10, 2019
Two Year Component Date Code Mandate
We are a contract manufacturer. We currently have a quality mandate to purchase components that have a manufacturing date code within 2 years. This is due to solderability issues we have had in the past. This mandate causes many problems with our purchasing components especially from large distribution channels.
Are there any industry standards or best practices concerning this issue? Is this shelf life issue as prevalent as it once was?
May 9, 2019
Solder Paste Thickness Measurements
On average how many locations should we measure on our PCBs to confirm our solder paste thickness? Our PCBs are approximately 10" x 10".