Soldering Techniques and Safety - Engineering World Health at UC

Soldering Techniques and Safety - Engineering World Health at UC
Soldering Techniques and
Safety
Lecture 1
Engineering World Health
What is Soldering?
• Joining electrical components to printed circuit boards
(PCBs) using a filler metal that has a relatively low
melting temperature (several hundred °F)
• Creates a strong electrical and mechanical connection,
although the former is more important
http://www.sciencebuddies.org/science-fair-projects/project_ideas/Elec_primer-solder.shtml#soldering
Solder Wire
• Consists of two main components
– Metal alloy: 60% tin and 40% lead (60/40 Sn/Pb), 63/37 Sn/Pb,
or 99.3% tin and 0.7% copper (99.3/0.7 Sn/Cu)
– Rosin core flux: “cleans” by removing oxide contaminants,
allowing the molten metal to flow freely
http://www.soldering.jp/sample.html
Soldering Process
• Metal solvent action (i.e., intermetallic bonding) between
the solder and PCB pad
– Alloy consisting of tin (from solder) and copper (from PCB)
• Having good wettability maximizes contact area.
http://www.powerguru.org/soldering-basics/
http://blogs.indium.com/blog/eric-bastow/intermetallics
Soldering Safety Tips
• Safety glasses are also a good idea.
http://sylviashow.com/printables/how-solder
Tinning the Tip
• Apply a thin layer of solder to the tip of the soldering iron.
– Protects the soldering tip from oxidizing
– Oxidation causes poor heat transfer and interferes with solder
adherence.
• Tin the tip whenever you are not using the soldering iron.
http://www.makerbot.com/docs/openvolver/
https://blog.adafruit.com/2010/05/04/post-a-photo-of-damagedoxidizedcorroded-soldering-iron-and-win/
Thermal Linkage
• Molten solder flows towards heat!
• Make sure the soldering iron is touching both the
component lead and the PCB pad.
– Otherwise, you will get poor thermal linkage between the
component and the PCB. Solder will not flow properly around the
component lead and on the PCB pad, creating a poor electrical
connection.
Bad!
http://www.circuitrework.com/guides/7-1-1.shtml
Good!
Desoldering
• Used to remove a poor solder joint
• Commonly done with solder wicks or solder suckers
• Reheat (melt) the solder joint and then apply the
desoldering tool.
https://www.rmgsailwinch.com.au/rmg/pages/How-To-Replace-FETs.html
http://www.electronic-discount.be/product-details/hq-des-pump01/shop.htm?lng=en
Soldering Techniques Summary
https://learn.sparkfun.com/tutorials/how-to-solder---through-hole-soldering
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