Brien Bush

Brien Bush has submitted responses to the following questions.

Tin Whiskers and Vapor Phase Reflow
There is not a lot known about tin whiskers other than they tend to occur under stress of an SNPB ...

Solder Alloy Investigation
The precise alloy may be difficult to determine without sending a sample out to be analyzed. I believe it would ...

Solder Paste Stencil Inactivity
The amount of time solder paste can remain on a stencil without activity is going to depend on the formulation ...

Solder Paste Print in Volcano Shape
There are a number of factors that can cause solder paste to peak. The peaks are caused by the paste ...

Solder Joint Blow Holes
It is possible to create blow holes when making an air tight seal. I think the most likely problem would ...

Pick and Place Machine Calibration
Depending on the type of pick and place machine you have will determine how often and when to calibrate. There ...

Water Wash vs. No-clean
The chemistry you decide to use in your manufacturing process is decided by the customer requirements, most efficient process flow, ...

Pad Missing ENIG Plating
My advice is to reject the boards. They were not manufactured to specification. They should be re-plated or scrapped at ...

Reflow Profile for Mixed Lead-Free and Leaded
The changes you will need to make depend on the type of board finish such as Enig, IAg, OSP, ISn, ...

SMT Target Component Placement
First you should make sure your pick and place machine is placing the part accurately. Depending on the size of ...

Insufficient Barrel Fill on Through-hole Components
There are many variable to achieving barrel fill in through hole technology. Flux activation, preheat time, board thickness ground plane ...

Channels To Reduce Voids in Large Pads
The expanding gas typically causes voids during the reflow process. These voids can be reduced or in some cases illuminated ...

Solder Balling Prediction Formula
Many variables will contribute to solder balling. The solder paste should be the right type for aperture size. Make sure ...

What Is This Contamination?
Without further investigation, I can only guess this board suffered a short. Most likely from an insufficient cleaning process and ...

BGA Placement Paste or Only Flux
With a flux only process for placing BGA's you have the potential for unsoldered connections and insufficient solder which will ...

Selective Solder System Purchased At Auction
The solder pots for these systems are manufactured to the alloy they are going to use. The reason being is ...

Reusing recovered solder paste
Mixing old solder paste with new is not a good practice. Solder paste waste has always been a valid concern ...

Stencil Pattern for Thermal Pads on QFNs
There is no one size fits all for thermal pads on QFN's. This is going to depend on the package, ...

0201 Pick & Place Nozzle Plugging
If you have paste getting squished out the sides high enough to get on the nozzle, you should have plenty ...

QFN Open Solder Joints
If you are experiencing opens with a QFN or in this case DR QFN, reflow is not occurring evenly or ...

Stencil Cleaning Frequency
The time between stencil cleaning is going to depend on your type of solder paste and printing process. If you ...

Customer Approval for Repairs
Depending on the type of damage, as long as you meet class 3 requirements, you can make repairs. Regarding customer ...

Gold Plating and Embrittlement
Gold embrittlement can be a significant reliability issue. Most PCB designers area ware of this and careful consideration is made ...

BGA Ball Sheer Testing
When a BGA is sheered from its terminations, the separation is going to take place at the weakest points. Some ...

Solder Paste Prep Before Use
Solderpastes are all manufactured for their specific purpose and use. I recommend youfollow yoursolderpaste manufacturer's instructions for the storage, use ...

Tiny Solder Balls After Reflow
There are a number of factors that can cause solder balls or solder splatter. Moisture being one which you have ...