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Gerard O'Brien
President
S T and S Testing and Analysis
Gerald O'Brien is Chairman of ANSI J-STD 003, and Co Chairman of IPC 4-14 Surface Finish Plating Committee. He is a key member of ANSI J-STD 002 and 311 G Committees Expert in Surface finish, Solderability issues and Failure analysis in the PWA, PWB and component fields.

Gerard O'Brien has submitted responses to the following questions.
What Caused SMT Pads to Oxidize After Reflow
ENIG does not oxidize after a reflow process or normal cleaning process. You need to verify what finish you actually ...
No-Clean Flux Residue After Selective Soldering
You need to determine the active species left in these residues in order to begin to make a decision on ...
Solution for Warped PCBAs
Sorry but you will not be able to flatten these assemblies. You would have to take the PWB above its ...
Recommended Fiducial Shape
This defect is not the result of the fiducial shape. All fiducial designs work fine with a normal HASL process. ...
What Is This Contamination?
Need to know the surface finish on the PWB. ...
Old Components and Blow Holes
Blow holes are primarily the result of poor hole wall generation of the PWB and defective or insufficient plating thickness. ...
Is Solder Mask Considered an Insulator
Solder mask was designed to prevent solder bridging period. Its ability to act as an insulator is an added benefit ...
Concerns With Silver Finish Component Leads
Ag3Sn platelets will form in the solder joint and are embrittling similar to AuSn4 but the necessary weight percentage to ...
Out-gassing and Cleaning
Due to the nature of the materials you are using, there will be outgassing under vacuum, although you did not ...
Solder Splashes During Wave Soldering
Have you confirmed the preheat profile is meeting the flux suppliers recommendations? If using a VOC free flux, it is ...
Soldering Components with Silver Pads
Ag dissolves at the rate of approx. 50 microinches /sec at soldering temperatures. What thickness of Ag is present on ...
Bottom Terminated Components and Vias
Unless you are using a dry film solder mask, you are kidding yourself with tenting to prevent flux and other ...
Gold Plating and Embrittlement
Gold embrittlement occurs at 5 wt.% in the solder joint although the industry usually defaults to 3 wt.%. You can ...
Blow Holes and Disturbed Joints
Have you verified the correct copper plating thickness by cross section? ...
Via Wall Thickness Test
There are a number of copper plating thickness "meters" where by you insert a probe into a plated through hole ...
A Generic Reflow Profile
The only way that a single profile could be used for all board designs would be if the rate of ...
What Causes Black Pad?
Black pad occurs during the immersion gold deposit and not during assembly which is responsible only for revealing the defect. ...
Improve DPPM for Wave Soldering Using Nitrogen
Adding N2 to your system will help with increasing your process window but may not be worth the cost as ...
Deionized Water Sample Testing
Exposure to atmosphere will definitely impact the resistance of the water as will the container you are using -- but ...
BGA Die and Pry Testing
The amount of dye penetration looks too extensive for Kirkendall voids. Are the images showing ball separation from the chip? ...
Mixing Different SAC305 Solders
Provided the new material meets the requirements of the appropriate JSTD, I would see no issues in mixing the SAME ...
Gold Plated Hole Defects
The first question is how many layers of interconnect are there in these holes typically? When you say exposed gold, ...
HASL vs. Immersion Gold
If you are leaving exposed pads or test points that will be susceptible to atmospheric attack then there have been ...
Insufficient Plated Hole Fill with Electrolytic Capacitors
What is the surface finish on the PWB, the lead to hole ratio being used and the aspect ratio/overall board ...