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PICAXE-08 ALARM PROJECT
revolution
© copyright 2002 - AXE102 Alarm Student Project Notes Version 1.1
Revolution Education Ltd. Email: [email protected] Web: www.rev-ed.co.uk
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Supported by:
Soldering the PCB.
The printed circuit board (PCB) is specially manufactured with a ‘solder resist’ layer to
make it simpler to solder. This is the green ‘lacquer’ layer that covers the tracks so that the
solder does not stick to these tracks. However for successful assembly the PCB must be
carefully assembled and soldered.
When soldering always make sure the solder iron tip is hot and clean. To test if it is hot
enough try to melt a piece of solder on the tip. The solder should melt almost instantly.
Then clean off the melted solder by wiping the tip on a damp sponge.
Remember that solder will only ‘stick’ to hot surfaces. Therefore never melt the solder on
the soldering iron tip and then try to ‘drop’ it onto the joint – this won’t work as the
joint will be cold and so the solder won’t stick.
To successfully solder you must hold the soldering iron in one hand and the solder in the
other. Therefore make sure the board is held on the table so it won’t move (e.g. use a
bulldog clip or get someone else to hold it for you).
Steps to soldering:
1) Clean the soldering iron tip on the damp sponge
2) Press the soldering iron tip against the pad on the PCB AND the leg of the
component. Count to 3 to give the joint time to warm up.
3) Keep the soldering iron in position and touch the solder against the joint. Allow
enough solder to melt to cover the joint.
4) Take the solder away first, then the soldering iron
5) Allow the solder to cool for about 5 seconds before trying to move the board.
After each joint is made make sure it does not accidentally ‘bridge’ across to other joints.
However be aware that some solder joints (e.g. on the two sides of the PICAXE download
socket) have two wires very close together that are already connected by a track (line) on
the PCB. In this case it does not matter if the solder joins together.
Tips!
1) Always start with the smallest components like the resistors. Then move onto larger
components like the IC socket and then finish with the tall components like
capacitors and transistors. Do not try to put all the components in position at once,
only do two or three at a time.
2) Always make sure that the components lie flat on the board before they are soldered.
When using components with long legs like resistors and LEDs, bend the legs so that
the component is held firmly in position before soldering.
3) Make sure the PICAXE stereo download socket ‘snaps’ into position flat on the board
before it is soldered.
4) Make sure that the components that only work one way around (LEDs, diodes,
transistors and capacitors) are correctly aligned before soldering (see the marks on
the PCB).
5) Piezo sounder wires are very thin. Make sure you do not overheat them or they may
melt.
6) Always thread the battery snap wires down and up through the two thread holes
before soldering. This helps make a much stronger joint which is less likely to snap
off.
