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Peter Biocca
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Senior Market Development Engineer
Kester
Mr. Biocca was a chemist with many years experience in soldering technologies. He presented around the world in matters relating to process optimization and assembly. He was the author of many technical papers delivered globally. Mr. Biocca was a respected mentor in the electronics industry. He passed away in November, 2014.

Peter Biocca has submitted responses to the following questions.
Components Jumping Around During Reflow
Component moving can occur due to the solvent pick up from the SMT environment or the solder paste formula having ...
Pin in Paste Solder Dropping
Pin in paste requires modifications to the stencil design as to avoid paste drop-off. It has to be also mentioned ...
Contamination Using Solvent Dispensers
Spot cleaning is always a reliability issue if not done correctly. It is recommended to avoid smearing flux residues across ...
Production Floor Temperature and Humidity Loggers
Humidity and temperature monitored  areas are areas where these parameters can possibly  impact the process yields and or quality. Some ...
Excess Flux Residue After Hand Soldering
The picture shows flux residue from soldering using solder wire which is not uncommon. Flux residue will depend on the ...
Test Probe Problems After Pin-In-Paste
No-clean flux residues do not vaporize completely in the reflow process. The solvent component of the flux system may be ...
Question About SN100 Solder
There is some data available. The vast majority of data is still by far on the SAC305 default lead-free alloy ...
Twisting Multi-strand Wires
Twisting wires after tinning can cause cracks to form exposing the base metal. This can promote oxidation and therefore solderability. ...
Head-In-Pillow Reject Rate
HiP can be serious reliability issues depending on the build and where it goes. For example, in many high reliability ...
Solder Caking to Bottom of PCBs After Wave
Solder sticking to the bottom-side of the board during wave soldering can be due to several items. These are listed ...
What Causes Component Rotation During Reflow
Rotation during reflow occurs due to two main factors. One is the wetting forces pulling on initially the most solderable ...
Through Hole Connector Solder Joint Hole Fill
Some methods that work are X-ray inspection at an oblique angle. Here you can check hole-fill and also if any ...
Solder Balls During Selective Soldering
Solder balls on the top side during selective soldering could indicate the preheating of the liquid flux is not sufficient. ...
Long Term Component Storage
The key is to preserve solderability and keep moisture out. While removing moisture is relatively easy by doing a bake ...
Reliability of Automated Soldering vs. Hand Soldering
Hand-soldering of SMD's can be as reliable as an SMT reflow process but some care is required. The important thing ...
Stencil Cleaning Procedure
This is not an unusual process to see when cleaning a stencil. It is important to not abuse the use ...
Unusual Solder Appearance
Surface effects with lead-free SAC305 can be normal. SAC305 is prone to micro-fissuring during cool down. Joints could look at ...
Dross Particles Sticking to PCBs
Dross appearing on the board can be due to several process issues. The impingement of the board has to push ...
Solder Paste Alloy Check
The industry recommends XRF spectroscopy as a test for lead and other metal constituents in solder joints. Again it is ...
Un-cleaned PCB Assemblies Potted
If a water washable flux was used, it is important to wash off completely all ionic residues and normally assess ...
Transfer Efficiency Greater Than 100%
Getting a higher height and larger volume of solder paste than the stencil thickness can occur due the compression of ...
Flux Aging Study
The typical parameters are acid number, density, solids percent and solderability testing using a wetting balance to determine the Force ...
Wave Solder Dross Contamination
Several process issues could cause dross sticking to the board. One being solder pot maintenance, dross may form on the ...
Mixing Different SAC305 Solders
SAC305 bar solder normally follows similar elemental specifications from one manufacturer to the other, so they are normally identical in ...
Tacky Substance Under Zero Clearance Parts
Solder paste flux is made of about 50% flux by volume with about 25% of the flux being various solvents ...
Syringe Dispensed Solder Paste for Hand Soldering
Solder pastes in syringes have lower viscosities and usually lower metal content 80-85% compared to printable solder pastes which have ...
White Discoloration After Ultrasonic Cleaning
Discoloration can be caused by several things. The first one I would check, is if the discoloration occurs across all ...
Gold Edge Contact Flux Contamination Failures
No-clean fluxes come in different classes, the ROL0 or ORL0 is preferred for reliability. This would need to be verified. ...
Gold Plated Hole Defects
Wave soldering requires careful optimization of several variables to insure adequate hole-fill. Is the flux you are using active enough, ...
Insufficient Plated Hole Fill with Electrolytic Capacitors
Hole-fill is a very common issue with wave soldering and has become even more so with lead-free soldering. The cause ...
Cleaning with Sodium Bicarbonate
Cleaning with sodium carbonate is an option however it is very important to remove all ionic cleaning by-products after the ...
Voids in leadless packages
Voiding in BGA assembly is due to a variety of reasons. No doubt the flux used in the solder paste ...
Copper Dissolution issue
If SAC305 solder is used in wave operation the high tin content will tend to leach copper from boards and ...
Epoxy replacement for solder??
Epoxies are being used as a solder replacement and for some time now. Some products just cannot take the heat ...