Gerard O'Brien

Gerard O'Brien has submitted responses to the following questions.

How To Remove Oxidation On SMT Components
Assuming that the parts are 100% tin plated, the oxide can be reduced using a solution of Thiourea and HCL. ...

Baking Old PCBs Prior To Reflow
You did not specify what the base material is for the PWB- FR4 vs polyimide for example. If your supplier ...

Flux Residue During Pin-in-Paste
The choice of whether to have hard or soft residues will be influenced if there is a need to electrically ...

How to Remove Oxidization from SMT Component Leads?
Unless the device package is something out of the norm, they should be able to be retinned- there are many ...

Causes of Annular Ring Dewetting
SAD defects as noted in the IPC4552A currently have no assignable cause although there is one technical paper in the ...

What Caused SMT Pads to Oxidize After Reflow
As the co-chairman of the committee responsible for ENIG, rework of the boards post nickel plating is NOT allowed and ...

Depaneling circuit board that contain BGA components
Depending on the proximity of the BGA devices to the edge of the PWB, it is normally prudent to minimize ...

Pad Missing ENIG Plating
As the co-chairman of the committee responsible for ENIG, rework of the boards post nickel plating is NOT allowed and ...

Tarnished OSP Circuit Boards
Changing colors of the Cu on OSP coated boards and associated soldering issues is a good indication of an issue ...

Adding Chlorine to a DI (Deionization) Water System
The addition of Cl to DI water fundamentally turns it back into city water. The fact you have a DI ...

Reflow Profile for Mixed Lead-Free and Leaded
It all depends on the surface finish of the PWB. If you are using a non solder finish such as ...

OA Flux Turning Blue
I am assuming you are talking about flux in the fluxer and not in its original container - most likely ...

Contamination From Anti-static Foam
A soak in IPA will only be useful if the material is soluble in a polar solvent which it may ...

How to Re-qualify BGA Spheres
I take it you mean for solderability. This can be done either with a wetting balance and using a low ...

Cleaning Under Low Clearance Components
Your concerns are valid however the ability to clean will depend on the surface tension of the water solution you ...

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 Splashing 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 and ...

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?
Blackpad occurs during the immersion gold deposit and not during assembly which isresponsible only for revealing the defect. The primary ...

Improve DPPM for Wave Soldering Using Nitrogen
AddingN2 to your system will help with increasing your process window but may not beworth the cost as your defect ...

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 ...