Neil Poole

Neil Poole has submitted responses to the following questions.

Tarnished OSP Circuit Boards
OSP organic solderability preservative is designed to prevent oxidation and therefore loss of solderability. Having said that id does have ...

Cleaning Under Low Clearance Components
Cleaning under low standoff components is particularly difficult. With appropriate equipment and process setup it is possible to clean under ...

Initial Screen Print Test Board
Many modern pastes will print better if they are subjected to a kneed cycle (2 to 4 sweeps of the ...

Solution for Grape Effect
Your situation leaves little room for maneuver, the problem is flux exhaustion due to the high surface area to volume ...

Frequency of Checking Solder Paste Viscosity
If the solder paste has been correctly shipped and stored then there should be no requirement to measure viscosity. If ...

Solder Paste Viscosity
Increasing the metal loading will drive the viscosity up even with the current PSD, and with the typical metal loading ...

Cause of Green/Blue Oxide Buildup
The colour that you are observing is most likely due to the formation of complex hydrated metal chloride salts which ...

Rework of Underfilled Array Packages
Most underfilled array components will require a mixture of approaches both heat and mechanical energy will be required to remove ...

Conformal Coating Over Heat Sinks
To be safe the answer is yes and yes. Covering a heat sink even with a thin layer of conformal ...

SMT Component Glue Strength
There are twoadhesion strengths that are typically measured for SMT adhesives. There is theso called green strength that measures the ...

Deionized Water Sample Testing
It is technically possible for water to absorb CO2 from the atmosphere which will form acid, that in turn will ...

BGA Die and Pry Testing
Without additional information it is difficult to be definitive on the voids shown in the picture. Kirkendall voids are typically ...

Tacky Substance Under Zero Clearance Parts
I have heard of instances of this effect occurring in narrow gap situations. It is not a cure issue since ...

Reflow Causing Warp
I do not know how practical any of these suggestions are but you could look at a fixture to hold ...

Wave Solder Pot Contaminated with Lead
I do not know of any simple lead scavengers that you could put in the pot to lock up the ...

Components Jumping Out During Wave Soldering
I suspect it is probably a combination of things. Until the solder wets the leads the component has a degree ...

Use of Nitrogen for Hand Soldering
I do not know of such a thing and there are a number of potential problems the main ones are ...

Problems With Skewed D-Pak Components
I have seen this before and in a least one instance the problem was too much solder, it may be ...

Lead Free Reflow Oven Zone Count
The number of zones that you require is more dependant on the thermal complexity of the boards, and the efficiency ...

Conformal Coating Over No-Clean Flux
Many people do this the feasibility of doing so depend on both the conformal coating and the flux. There are ...

BGA Rework Residue Concern
The residue is most likely flux residue, if this is the case the question is best addressed to your paste ...

Application of Flux for Hand Soldering
There are two issues her. First is the application of the flux and controlling the volume dispensed, and the second ...

Most Important Factors for Screen Printing
Solder paste volume and solder print alignment are critical to the solder printing process. Depending on the situation, there is ...

Adding Weights to Small BGA's During Reflow
At first this sounds a good idea but it is fraught with potential problems. What will the extra mass do ...

Adding Weights to Small BGA's During Reflow
At first this sounds a good idea but it is fraught with potential problems. What will the extra mass do ...

Can Water be Harmful to Electronics Components?
The problem with water is the capillary forces that pull the water in to tight spaces and makes it very ...

Lifted Leads on QFP
I have no data on fall out rates so I can't comment however I have seen what sounds like the ...

APEX Trade Show Feedback
Personally I spent all of my time on the booth because we had so many technical questions, I did not ...

Problems with Insufficient Barrel Fill
Lead free alloys wet more slowly than do tin led alloys, and I suspect that this is the problem, the ...

Problems with Bubbles in Conformal Coating
It is difficult to help here without knowing the cure mechanism of the coating most silicones generate what is called ...

Which to Use - Rosin Flux or Water Soluble?
Because the residues of a water wash flux are to be removed typically much more aggressive activators (both acids and ...

Contact Pin Corrosion Problems
The cleaner that I have used are only good for removal of surface contamination and surface oxide which is chemically ...

Solder alloy function
The main reasons for choosing particular alloying elements are performance (mechanical reliability, melt point, etc) and cost. If we analyse ...

Reflow soldering lead free components creates tombstones
Tombstones are usually the result of confluence of multiple factors. Pad design, print location, print consistency, part placement and profile, ...

Reflow of "high-lead" flip chip device
With the data that you have presented it is not clear what the route cause of your problem is. It ...

Can we convert our existing wave soldering machine to use lead free?
It is definitely possible to solder traditional lead containing finishes using lead free alloys in a wave solder bath. However ...

Can I use my old oven for lead-free reflow?
This will depend not just on your oven but also on your board. The key here is how effective and ...

What is the best solder lead free alloy for step solder process on assemblies with SAC305?
The work done by the IPC Solder Product Value Council no discernible difference between the various SAC alloys that were ...