Workshop Practice Flashcards
Hazard
e.g. Hot Stove
Exposure
e.g. Cooking on stove
Consequence
e.g. Getting burned from stove
Friable
Easily crumbled
GHS
Globally Harmonized System of
Classification and Labelling of Chemicals
Two types of clamp
Bar Clamp, G Clamp
Brazing
Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metal.
Eutectic
A homogeneous mixture of substances that melts or solidifies at a single temperature that is lower than the melting point of any of the constituents.
Common solder alloy in electronics:
63 Tin / 37 Lead (or 60 / 40), melts around 180-190 degrees.
Common solder alloy for joining aluminium:
Tin / Zinc
Common solder alloy for strength above room temperature:
Lead / Silver
Common solder alloy for strength at high temperatures:
Cadmium / Silver
Common solder alloy for aluminium and corrosion resistance:
Zinc / Aluminium
Uncommon solder alloy in electronics:
Tin / Silver and Tin / Bismuth
Flux (soldering)
Flux is a chemical cleaning agent used before and during the soldering process of electronic components onto circuit boards.
Two types of Flux
Acid (for plumbing) and Rosin (for electronics)
Three types of ‘Soft-Solder’ Flux
Water-Soluble Flux, No-Clean Flux, Rosin Fluxes
Rosin Flux comes in three forms:
Non-Activated (R), Mildly-Activated (RMA) and Activated (RA) formulations
RA and RMA fluxes contain rosin combined with:
An activating agent, typically an acid, which increases the wettability of metals to which it is applied by removing existing oxides.
Three types of soldering:
Soft-Soldering, Silver-Soldering, Brazing
Wetting
Wetting is a condition where the solder has become molten at its eutectic temperature with an adequate amount of flux.
Wicking
When solder is drawn up into a braided wire between the strands by capillary action. Can be used as a technique for removing solder.
Demarcation Temperature between Soldering and Brazing:
450 °C
Wave Soldering
Wave soldering is a bulk soldering process used in the manufacture of printed circuit boards. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave.
PCB
Printed Circuit Board
De-laminating
When too much heat is applied to a circuit board, melting the lamination layer and freeing the copper circuit.
‘Easy’, ‘Medium’, or ‘Hard’ Solder refers to what?
Melting Point
Dry Joint
A “dry joint” occurs when the cooling solder is moved, and often occurs because the joint moves when the soldering iron is removed from the joint.
Cold Solder
This is when parts being joined do not exceed the solder’s liquidus temperature, resulting in a “cold solder” joint.
