Doug Dixon

Doug Dixon has submitted responses to the following questions.

Solder Balling Prediction Formula
The mid-chip solder ball occurs when solder is squeezed under the component and away from the pad and is unable ...

Components Falling Off During Wave Soldering
Short answer on this one. Yes. The lacquer coating may not be compatible with some adhesives, I would recommend you ...

Dam & Fill vs. Conformal Coating
Dam& Fill applications were designed for "Chip on Board" applications. Chip on Board technology is where a semiconductor wafer chip ...

Syringe Dispensed Solder Paste for Hand Soldering
Dispensing solder paste can be a science in itself and in my opinion best to stay away from. When dispensing ...

Conformal Coating in Low Humitidy Environments
Low humidity environments have no impact on the performance of a cured conformal coating.However, in some cases the relative humidity ...

Problems With Skewed D-Pak Components
This is a relatively common defect. The main cause is due to too much solder under the heat sink (big ...

Flux Recommendation for BGA Rework
Tacky fluxes are generally the most commonly used product for re-working BGA devices. They have the benefit of staying where ...

Is Rework Unacceptable?
The answer to this is depends, they are after all the customer and so it is their choice, you just ...

Uncontrolled Environment Causing Problems
Both high and low humidity can have an effect on the life and print capability of any solders. Lead free ...

Solder Paste Mixing After Storage
You are doing nothing wrong with your current practice. As long as you use the same method each time it ...

Solder Paste Volume for BGA Rework
It depends on the technique employed for the rework. If you are dispensing, or printing, so the volume constraints will ...

Water Washing Pressure - Lead Free Reflow Oven Zone Count
Some machines give pressure / power ratings for their jets, but this is not always an accurate rating of what ...

Soldering to Hard Gold
Assuming that 30 millionth of an inch are 0.76um Au over 3.8um Ni, the thickness of gold would be quite ...

Board Spacing During Reflow
It depends, different ovens have different thermal capabilities, and different boards will have more or less thermal demands. As a ...

Components Lifting During Wave Soldering
This can be caused by buoyancy, the upward force that a fluid exerts on an object less dense than itself, ...

Best Way to Eliminate Dross?
When targeting to reduce dross in any kind of solder pot, it is important to reduce the cause of dross ...

Intermittent BGA Test Problems
This would seem to be a classic example of what is known as head in pillow failure. The effect is ...

Reflow for Metal Core PCBs
I assume that with metal core, we are looking at very heavy PCBs. These offer a number of interesting differences ...

Application of Flux for Hand Soldering
The best way to apply flux with precision is to choose flux gels in a cartridge. By using a fine ...

Guidelines for Pin-in-Paste
I do not have any fixed guidelines except to say that this is essentially a volume calculation. If you know ...

Post print inspection issue - Wave solder pallets
Since you have no way of reworking defective boards, it is worth looking at optimizing the print and inspection processes. ...

Pros and Cons of Cleaning No-clean
Cleaning a no-clean flux requires both, time and effort. It is necessary to match the chemistry to the flux, all ...

Solder Paste Volume
Initially, you will need a thumb-sized roll of paste. You also want to make sure your bead of paste extends ...

No Clean or Water Soluble for QFN Components
I would recommend the no-clean process. The problem with a water soluble process for QFN and DFN devices, is that ...

What is the Shelf Life for a Syringe of Solder Paste
The shelf life of our solder pastes is product specific. Most of our pastes have a shelf life of 4 ...

Voids in leadless packages
There are arguably many variables that contribute to the increased voiding characteristics of SAC alloy solder joints. Strictly speaking from ...

Urethane Conformal Coating Problem
Specific to adhesion, there are a couple of likely candidates:contamination of the board with silicone contamination of the product with ...

Part Movement During Reflow
The fundamental reason for component shift is solder surface tension. All things being equal, the molten solder will try to ...

Voids in BGA's
There are numerous process and materials-related variables that can contribute to void formation, but three primary physical differences between SAC ...

Component Shift During Reflow
The fundamental reason for component shift is solder surface tension. All things being equal, the molten solder will try to ...

Chemical composition of flux?
Fluxes contain a wide variety of components and especially in the case of solder paste specific chemicals may be present ...

Clean before wave soldering
The first objective especially if the PCB assembly is being manufactured using No clean technology is to avoid handling and ...

Coating or encapsulating tin-lead solder joints?
The dangers of lead free solder do not come into play unless someone is touching the solder joints or in ...

SMT Epoxy for lead-free wave
This is not likely a relationship between SMT glue and flux. The SMT glue should be fully cured prior to ...

What exactly is intermetallic spalling?
Intermetallic spalling is usually used to describe the break up and migration of the secondary tin copper intermetallic into the ...

Tombstone problems
Tombstones are common in double sided reflow processes. Tombstoning can be fixed with in a number of ways. As you ...

Using tin-lead solder on RoHS parts
Traditional tin-lead materials are not compatible with lead-free device finishes. Because proper reflow for lead-free materials can only be achieved ...

Wave Solder fluxing
Two reasons for the preheat are to remove carrier solvent, and reduce thermal shock as the PCB hits the wave. ...

Soldering reliability using SAC 305...
Mixed metal manufacturing is, in fact, quite commonplace in today's manufacturing environments. Most often, due to component and board availability ...

Using non-RoHS components in RoHS
Because of the number of products (military, medical, etc.) that are exempt from RoHS, mixed metal manufacturing is becoming very ...

Flux residue after baking
The main effect is that the flux residues will soften and may flow under gravity. This depends a little on ...

Halogen Free PCB legislation
I think the questions confuses two different approaches for different classes of materials. The Montreal protocol included CFC materials in ...

Reflow oven profiles
A ramp profile also referred to as Ramp-to-Spike profile, is a reflow profile that increases to the reflow temperature in ...

Wave soldering lead-free components
Tin and silver finishes have been widely used for both surface mount and through hole components for many years due ...

Tombstone problems
In practice, solderability of lead-free surface finishes is generally proving to be good enough in normal processes. Although Pb-free alloys ...

Reflow Oven Profilers
How important is reflow oven profiling to producing quality circuit boards? There are several reasons for why thermal profiling is ...