BOM's are killing me

[propa]

Hello,

Brief update, yay I can now successfully solder SMD components! Took a few attempts, but can now hand solder down to 0805 passives and also do 5050 rgb leds by hand, the iron damages the cases slightly but still work fine. The next attempt I tried using solder paste and a hot air gun and damn there's a satisfying moment when those components wiggle about and then just suck into place, amazing to watch!

So now I've got the confidence to move to an actual IC and try and make an actual MCU! I think I've had just about enough practice to just about know what I'm doing with Eagle and routing, although there may be a critical step I've overlooked and that's the using the correct part, passives and MCU should be fine, but it's things like crystals and pushbuttons, and the lack of labeling of part number or manufacturer number in the library parts I'm using. So the final stage is kinda killing me.

I've tried using BOM uploaders on Farnell and had little success and had to manually re-enter everything so it defeats the point of uploading a BOM. What online retailers do you lot use to shop for components? I'm guessing you lot stateside people use Digikey, if so does it have a decent way to upload BOMs?

How do know what the right type or brand of component to use? For example on the passive side is it a bad idea to use the cheapest one's listed on digikey or farnell? There's probably a reason why they could be cheap right?

Also is there a trusted set of library packages I should be using? I think part of my headache is using Sparkfun's eagle library, no manufacturer part number. Also why do I get the feeling the response is going to be "MAKE YOU'RE OWN BLOOMING PACKAGES YOU MISCREANT"

Anyways sorry or thank you for the rant

 

[PaulStoffregen]

For prototyping circuit boards, I use Kester #331 solder and 2331 liquid flux. It makes everything so much easier and better. But it's an organic acid flux, so you absolutely must wash the boards in hot water. I bake dry for 15 min in an oven at 170F.

On cheap passives, usually resistors are fine. For ceramic capacitors, usually you want X7R or X5R for power supply decoupling and other general uses, or NP0 or C0G type for special analog needs like filters where variance in the capacitance could distort the signal. The Y5V types can vary in value tremendously, and the Z5U types should be avoided except for "disposable" products like toys & novelty items that are used only briefly.

 

[xxxajk]

I find that chipquik flux washes off easier. I use:
PASTE: SMD291SNL10T5 or SMD291SNL10T3, T5 is for fine pitch components, T3 is a bit cheaper, and may or may not work depending on the pitch of the components.
FLUX: SMD29130CC, this is a high tack flux.

Note that there has been a MLCC (Multi-Layer Ceramic Capacitor) global shortage for over a year now, so don't get upset if a capacitor cost a bit more, or if there is a 22week lead time for the absolute cheapest one.