Ramsey 2013 Catalog - page 75

Soldering Guide
75
Shop online at
Call Toll Free 800-446-2295
KIT PC-BOARD SOLDERING
Unprofessional soldering practices are the nightmare of ANY electronics manufacturer or service shop. GOOD soldering is essential to the performance of
your project. A “cold” solder connection is caused by too little heat OR by heating only the component wire and not the wire and PC copper foil together.
The tell-tale sign of too little heat is a dull, rough-looking connection. If you heat only the wire, the solder forms a cute ball around the wire, and rosin may
completely insulate your ball from the copper.
SOLDER BRIDGES
You probably know that a solder bridge is a perfect and unintended connection of two PC-board points that should NOT be connected. They happen most easily
when soldering IC's and other devices with pins close together. The only technique for avoiding solder bridges is for you to be in complete control of the tip of your soldering pencil.
The best single tools for avoiding bridges are a proper point on the soldering iron, bright light, perhaps with some magnification of your work, and thin diameter solder.
Study your connection before you zap it with heat and solder. Choose the best “approach angle” for the iron's tip to heat the connection. Plan ahead to make the solder do what
YOU want it to do, and you just won't build any solder bridges!
GOOD
BAD
ROSIN
TEN COMMANDMENTS OF GOOD PC-BOARD SOLDERING
1.
If the soldering iron tip is covered with burned rosin, it cannot properly heat your connection
2.
If you heat only the wire and not the wire and PC trace together, a cold, bad connection is likely.
3.
If your soldering tip is big enough to bridge two adjoining connections, it probably will!
4.
Dirty, grubby solder will contribute to dirty, grubby connections.
5.
Any use of acid core (plumbers!) solder in electronics work will destroy everything...DON’T USE IT!
6.
A connection in a large area of PC-board copper requires more heat than one pin of an IC.
7.
If your connection looks dull or brittle, it's no good.
8.
If your connection looks like a ball instead of a shiny cone, it's no good.
9.
Thin fresh shiny rosin core solder is easier to use for PC-board work than thicker “hardware store” solder.
10.
Pre-tin any stranded hookup wires leading in and out of your PC-board kit project. It will prevent problems later!
THE PAINFUL BUT USEFUL ART OF “DE-SOLDERING”
The art of PC-board “de-soldering” is harder than good, basic soldering, but it is a skill necessary for service technicians - or experimenters who like to sal-
vage parts from scrapped PC boards - and for folks who make mistakes in building kits!
Solder is efficient and stubborn, especially once it has adhered correctly to a PC-board connection. Those days of clipping away an old part from
big solder lugs, and easily soldering the new part, are gone except for keeping vintage equipment in good repair.
“Desoldering” is the skilled and swift removal of all solder from a PC connection. You re-melt the solder and “suck” it away as cleanly as possible.
Most beginners will have reasonable success with any spring-powered vacuum device available from Ramsey or an electronics store. Remember
the following...
• Follow kit-building instructions very carefully so that you will not need to do needless "desoldering”
to get it working!
• If possible, ask an expert to SHOW you how to “de-solder”.
• Use a bright light and magnifier to SEE what you are doing.
• Your goal is to get the connections clean enough so that you can easily re-solder the new part.
SOLDERING SURFACE MOUNT ICs
Look for pin one, marked with a dot or notch, and orient it in the same direction as shown in the Parts Layout Diagram and PC board
silkscreen. Place it on the board with tweezers so that the pads line up with the pins and use the finest tip that you own on your soldering
iron.
Solder only pin one for now. It may help to hold the IC down with a finger or the tweezers while you solder. Once pin one is soldered, check the ori-
entation to make sure that all the pads still line up. If not, re-heat pin one and gently move the part with the tweezers until it is in position.
When finished, solder the pin in the opposite corner of the IC. This prevents accidentally reheating pin one and moving the part. Now that you have two
pins soldered, solder all the rest of them while being careful not to short any pins together. Should that happen it is useful to have some solder wick
available to “mop” up any extra.
SURFACE MOUNT SOLDERING TECHNIQUES
The following pictures should help you learn the proper way to solder those tiny surface mount components. Don’t be intimidated by their size; by following a few simple proce-
dures you can become an SMT pro in no time!
Patience is the key when installing surface mount compo-
nents. Typically, the first step (after identifying the compo-
nent) is to “tin” one of the PC traces that will connect to the
part. This is by far the easiest method for surface mount sol-
dering.
Once this is accomplished, the part can be installed by hold-
ing it with tweezers in contact with the “tinned” trace and re-
heating the solder.
Be careful that the iron tip does not come in con-
tact with the “tab” on the body of the chip compo-
nent when reheating the solder. Overheating of
this solder tab can cause a fracture of the bond to
the component, causing an intermittent connec-
tion.
Once you have the part in place, solder the other
side, or in the case of a part with more than two
leads, solder the rest of the leads or pins.
1...,65,66,67,68,69,70,71,72,73,74 76,77,78,79,80
Powered by FlippingBook