Kevin Mobley

Kevin Mobley has submitted responses to the following questions.

Solder Alloy Investigation
The best non-destructive method for determination of the alloy used would be XRF (X-ray Fluorescence Spectroscopy). Many labs that service ...

How To Remove Oxidation On SMT Components
The best option would be to re-tin the parts if they are not expensive, replace if they are hard to ...

Baking Old PCBs Prior To Reflow
If the boards are sealed with desiccant and the humidity indicator card is below 10% you shouldn’t have to bake ...

Design Specs for Selective Soldering
If you have got the clearances around the leads you’ve covered the most common problem. Good panelization will make it ...

3D AOI Solder Joint Qualification Parameters
What you are seeing is very common with AOI systems. We typically start with the IPC Class set then edit ...

Design Considerations and Impact on Assembly
A few of the most common issues include: Ground planes directly connected to Plate Through Holes – failure to use ...

Matte Black Solder Mask Defects
The pictures look almost like the PWB was damaged in handling where something abraded the surface. This should not occur ...

Oxidation of Solder Balls During Secondary Reflow
I'll assume we're talking about solder spheres on a BGA device. Solder spheres can oxidize to some degree in a ...

Acceptability Standard for Plated Hole Barrel Fill
This looks like a condition referenced by IPC-A-610 paragraph 1.5.1.7 on Specialized Designs, "where an industry consensus document cannot address ...

BGA Component Cleaning Spec
I would say that the cleanliness requirements after rework would be the same as those imposed by the user as ...

Tented Via Options and Tradeoffs
Voids are common where the applied solder paste wicks into the vias in the thermal pads under the part. There ...

Challenge Wetting Solder to Brass Pins
I cannot find a requirement that the tip of the lead be covered in solder in IPC-A-610, as long as ...

Seeking Advise for a Solder Reflow Recipe
You should be able to do this with a 7-zone oven if it is a pretty good convection oven. You ...

Hand Sanitizer Contamination
The material warnings saying "prolonged soaking may cause damage to metal instruments" and "follow pesticide disposal instructions" would give me ...

Assembly Question for Soldering USB Connectors
For this volume you may want to consider a selective solid solder deposit on the PWB. This is a process ...

How to Remove Oxidization from SMT Component Leads?
Re-tinning the parts using a flux active enough to remove the oxidation is probably the best route. There are numerous ...

Causes of Annular Ring Dewetting
Dewetting is usually a case where the solder initially wets the surface then pulls back when the surface that was ...

Critical Part Fixture During Reflow
Most SMT parts normally center themselves during reflow pretty well. Between self-centering in reflow and the accuracy of most recent ...

Aluminum Trays and Rapid Static Discharge
I would recommend static dissipative trays for transport. The rapid discharge can be harmful to some components, and could possible ...

Water Wash vs. No-clean
No-clean flux residue always has some possibility of electrochemical migration resulting in dendrite growth, although the likelihood is fairly low ...

Solder Contamination Sources
The most common sources of solder pot contamination will typically be material included in the assemblies that you are running ...

Maximum Allowable Time Prior to Washing When Using Water Soluble Paste
This is often an issue that is driven by the "end of shift, can I wait until tomorrow to wash ...