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Topic: Problem choosing the right components (Read 797 times) previous topic - next topic

vectorel

Hi there. I'm new to this forum.

I want to build an Arduino Fio with SMD components and I don't have much knowledges about electronics. I have already created the schematic and board layout with EAGLE. There are no problems for the microcontroller and the integrated circuits, but I don' know what resistors I should take. They are 0603 tipe, but I don't know that tolerance must have and above all, how many watts should be; 1/10 or 1/8 watt? Same problem with the capacitors, which tolerance they mast have?

Thanks in advance.

Erdin

You do know that an Eagle file is available ?
http://arduino.cc/en/Main/ArduinoBoardFio

The capacitors are only for decoupling and for the X-tal. They can be 50% tolerance.

The resistors of 1k are for the leds.
Suppose voltage drop 1.5V for a red led.
(5-1.5V)/1k = 3.5mA
Dissipated power = (5-1.5V) * 3.5mA = 12mW
The tolerance of the resistors can be 20% or even 50%, and it will still work.

vectorel

Thanks, I have downloaded the file of  the Arduino Fio.

Do you think that with a stencil and the hot air station I can solder all the components without any big problems?

MarkT


Thanks, I have downloaded the file of  the Arduino Fio.

Do you think that with a stencil and the hot air station I can solder all the components without any big problems?


With good hot air station it should be relatively easy - don't hurry, set the temperature right and wait (overheating
a board will damage it).

If you can apply paste through a stencil it will make things much neater and more reliable (too much solder paste
causes solder-bridges which are a fiddly problem to solve).

Practice on old bits of copper board and spare components first - solder paste is pretty magical technology so
long as surfaces are clean (I rub boards with steel wool to get a bright finish, then carefully wipe with a cloth
to remove any stray steel fibres).

Get your boards made up with solder-mask if you can.  Find "no-clean" solder paste (I use "ChipQuik lead free rework solder paste"

Lead-free is important, solderpaste gets into your skin really easily and normal soap/detergent will not remove it
efficiently.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

vectorel


With good hot air station it should be relatively easy - don't hurry, set the temperature right and wait (overheating
a board will damage it).

If you can apply paste through a stencil it will make things much neater and more reliable (too much solder paste
causes solder-bridges which are a fiddly problem to solve).

Practice on old bits of copper board and spare components first - solder paste is pretty magical technology so
long as surfaces are clean (I rub boards with steel wool to get a bright finish, then carefully wipe with a cloth
to remove any stray steel fibres).

Get your boards made up with solder-mask if you can.  Find "no-clean" solder paste (I use "ChipQuik lead free rework solder paste"

Lead-free is important, solderpaste gets into your skin really easily and normal soap/detergent will not remove it
efficiently.


Thanks, very clear.
I'm practicing on old boards for the moment, until I'll be ready.

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