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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
Pinin paste requires modifications to the stencil design as to avoid pastedrop-off. It has to be also mentioned that the ...
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
Thereis some data available. The vast majority of data is still by far on the SAC305default lead-free alloy since 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
HiPcan be serious reliability issues depending on the build and where it goes.Forexample, in many high reliability applications, automotive or ...
Solder Caking to Bottom of PCBs After Wave
Soldersticking to the bottom-side of the board during wave soldering can be due toseveral items.Theseare listed below:Insufficient fluxFlux activity notsufficient ...
What Causes Component Rotation During Reflow
Rotationduring reflow occurs due to two main factors.Oneis the wetting forces pulling on initially the most solderable areas andthe other ...
Through Hole Connector Solder Joint Hole Fill
Somemethods that work are X-ray inspection at an oblique angle. Hereyou can check hole-fill and also if any large voids ...
Solder Balls During Selective Soldering
Solder balls on the top side during selective soldering couldindicate the preheating of the liquid flux is not sufficient.If solvent ...
Long Term Component Storage
The key is to preserve solderability and keep moisture out.While removing moisture is relatively easy by doing a bake oxide,increases ...
Reliability of Automated Soldering vs. Hand Soldering
Hand-soldering of SMD's can be as reliable as an SMT reflowprocess but some care is required. The important thing to ...
Stencil Cleaning Procedure
This is not an unusual process to see when cleaning a stencil.It is important to not abuse the use of ...
Unusual Solder Appearance
Surface effects with lead-free SAC305 can be normal. SAC305 isprone to micro-fissuring during cool down. Joints could look at times ...
Dross Particles Sticking to PCBs
Dross appearing on the board can be due to several processissues. The impingement of the board has to push away ...
Solder Paste Alloy Check
The industry recommends XRF spectroscopy as a test for lead andother metal constituents in solder joints.Again it is important to ...
Un-cleaned PCB Assemblies Potted
If a water washable flux was used, it is important to wash offcompletely all ionic residues and normally assess cleanliness ...
Transfer Efficiency Greater Than 100%
Getting a higher height and larger volume of solder paste thanthe stencil thickness can occur due the compression of the ...
Flux Aging Study
The typical parameters are acid number, density, solids percentand solderability testing using a wetting balance to determine the Force versus ...
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 elementalspecifications from one manufacturer to the other, so they are normallyidentical in composition.Adding one ...
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 usuallylower metal content 80-85% compared to printable solder pastes which have 90+%,separation ...
White Discoloration After Ultrasonic Cleaning
Discoloration can be caused by several things. The first one Iwould check, is if the discoloration occurs across all solder ...
Gold Edge Contact Flux Contamination Failures
No-clean fluxes come in different classes, the ROL0 or ORL0 ispreferred for reliability. This would need to be verified.Functionality may ...
Gold Plated Hole Defects
Wave soldering requires careful optimization of severalvariables to insure adequate hole-fill.Is the flux you are using active enough, is the ...
Insufficient Plated Hole Fill with Electrolytic Capacitors
Hole-fill is a very common issue with wave soldering and hasbecome even more so with lead-free soldering.The cause of insufficient ...
Cleaning with Sodium Bicarbonate
Cleaning with sodium carbonate is an option however it is veryimportant to remove all ionic cleaning by-products after the wash ...
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 ...