Soldering! (Rhymes with Doddering) - PowerPoint Presentation

Slide1

Soldering!

(Rhymes with Doddering)

S.R.Norr

, UMDSlide2

Definition: Soldering

A process in which two or more items (usually metal) are joined together by melting and putting a filler metal (

solder

) into the joint, the filler metal having a lower melting point than the adjoining metal. The intent is to create a strong MECHANICAL joint

In electrical soldering, electrical conductivity of the joint is equally importantSlide3

Composition of Electrical Solder

Lead is great! But Lead is also BAD (poisonous)!

60/40 Solder, comprised of 60% Tin and 40% Lead, is a great general purpose solder

63/37 Solder is eutectic, having a sharp phase transition from liquid to solid

Different alloys have different melting points and different mechanical strength

Under the RoHS Directive (Restriction of Hazardous Substances), Lead is banned from modern electronics

Most lead-free solders are SAC – Tin, Silver and Copper alloys

Avoid using Lead alloys with components that are silver coated

Flux Core (Rosin Core or Acid) – Many solders have flux inside the wire, to improve adhesion to the joint by chemically cleaning the surfacesSlide4

The Rules of Soldering

The first Rule of Soldering club is, “Don’t talk about..

NO. The first Rule of Soldering is,

“Keep your Tip Clean!”

Clean the soldering tip by washing it in solder, then dabbing it on a wet sponge or brass shavings

This serves two purposes:

It minimizes contamination in the solder joints (carbon,

etc

)

It prevents the tip from oxidizing (IMPORTANT)

The second Rule is that solder

flows toward heat

. Get your parts hot with the tip, then bring your solder into the heat.

If your parts aren’t hot enough before the solder arrives, you’ll get poor adhesion. Slide5

General Rules of Thumb

1. Less is more – Use just enough solder to cover the joint. You’ll notice that excessive solder will “bead up”. The correct amount will tend to lay flat.

2. Pay attention to mechanical strength – Don’t expect solder to be the primary mechanical fastener for parts that receive a lot of wear and tear

3. Most soldering is very quick, a few seconds to heat up a joint and apply the solder. If you have a lot of connections on a single part, it will get hot. Try to alternate the locations on the part and/or take a break to let things cool down. Consider a heat sink on the part to delay the temperature rise.Slide6

Soldering Temperature

Temperature is important

You must have a temperature high enough to get your parts hot enough to attract solder

You want to avoid temperatures higher than necessary to protect your parts and reduce oxidation of the solder and your tip

A general purpose temperature is

350 Celsius (660 F)Slide7

Soldering Irons:

15 Watt Pencil

70 Watt StationSlide8

The TIP:

“B” Series – general purpose, Needle tip – Fine work,

chisel tip – Parts RemovalSlide9

Joining Two Wires:

The Western Union Splice:

Then tin it with solder

Then cover with heat shrink

electronics.stackexchange.comSlide10

Soldering Through-Hole Components:

electronics.stackexchange.com

dansdata.com

angelfire.com Slide11

De-Soldering – A Nasty Business

Solder Suckers

Wicking Braid

pakronics.com.au

starwarsbulgaria.comSlide12

Surface Mount Components

Soldering of surface-mount parts is usually performed with automation

Soldering paste is applied to a printed circuit board, usually using a stencil or screen printing

Parts are placed on their proper pads (covered now with paste) with a “pick and place” robot

The board is inserted into a Re-Flow Oven and baked to make the solder paste liquify and adhere to the parts and board