I was planning to buy a few hundred of standard SMD resistors, capacitors, LEDs and more. Three questions:
What size should I get? I’m used to old soldering and managed to hand solder an SMD board with 0805 caps but it was painful so I just ordered a Controleo2 reflow oven. I’m thinking of just getting 1206 sized components. What are the pros/cons with this apart from the obvious that one is smaller but harder to deal with?
Where should I get it? I usually stock up on cheap components from HongKong or Shenzhen but I don’t trust the quality. Where would you get a few hundred of each from? Mouser, DigiKey, or AliExpress/Ebay?
Would it make sense to do a group buy of these items or is the price drop/difference not worth it?
At Digikey’s plain vanilla SMD resistors are 0,1@1pc dropping to 0,005@100pcs. That’s 0,5 for 100. I did a quick check with AliExpress and found something around 0,39 for 100. At an affordable (or somertime free) shipping you will wait 3-5 weeks. Is it really worth the waiting? Your option…
As for the size: 1206 is a sure bet, but with some routine 0805 is doable.
More so as you have that reflow oven (mine is a modified T-962). 0805 is mostly 0,125W, while 1206 typically are 0,25W. There are 0.25W or even 0.333W (Susumu) 0805s, but they are app. double to triple price or even more, depending on the resistance. Obviously some high current shunt resistors are available only in 1206 because of power dissipation.
You can route 1 10 mil trace under a 0805 with 10 mil track clearance, while you could route 2 10/10mils tracks under a 1206. But then, routing tracks under SMD components like resistors, capacitors and inductors is a heavily disputed practice. Reliablity of the solder joints and other aspects factor in there. But that only goes for professional, commercial, high qualitiy and high reliabilty designs subject to extended temperature ranges and/or extrem environmental conditions.
And there is a possible issue with crosstalk, prominently relevant in routing audio signals under SMDs carrying digital signals on their pads, or with high frequency designs (capacitive load between track and pads).
For us John Does (and for most of companies out there) such considerations are pretty irrelevant.
I standardize on 0805. Think it’s a good balance between size of components and availiability in the marketplace. Also still large enough to allow you to work on your soldering skills.
I ordered something similar to this in the past and still have the kit of parts in my lab, though mine looks slightly different (straight lines of components instead of the curved reels):
Really anything that has a wide range of components will be good to have on hand. Note that your 1K and 10K values will probably run out first (and maybe a standard LED value like 220 ohm), so it’s worthwhile tacking those onto a digikey order at some point in the future as well.