School me on SMD Components
- Thread starter Big Monk
- Start date
Brett
Well-known member
Most of what I’ve seen used for hand assembly starts around 0603 or 0805 for resistors and film caps.
SOIC-8, SOIC-16, and SOT-23 seem most common.
szukalski
Well-known member
People have preferences, and those more knowledgeable than I will have science.
My take..
My take..
- 0805 resistors for a pedal I expect to be able to mod or fix.
- 0402 resistors for modular components I expect to replace outright (like a relay or add-on boost). Watch your power dissipation. If your circuit is a single resistor with 9V.. well.. you're asking for it.
- Capacitors, try to stay 0805 and above. The smaller the cap, the more loss of capacitance as voltage increases. Try to stay to C0G where you can.
- Start to love vias.
Big Monk
Well-known member
Big Monk
Well-known member
Smrtokvitek
Well-known member
From my experience 0603 is the smallest I want to solder by hand. It also depends on how many parts you want to assemble. It is really exhausting to solder a lot of small components in a row in one sitting.
I like to use resistors in MELF packages. The miniMELF 0204 package is basically the 1206 size. It is easily solderable. The 0207 MELF is huge in comparison and also really easy to work with.
The stencil and a paste are a way to go but you also need a reflow oven. I use a rebuilt toaster oven but it is another piece of specialized equipment you need. Or just order the assembly service if you feel lucky.
Be aware that the physical size also affects parameters like a maximum voltage (resistors and capacitors) or capacity in caps and hence the price. Sometimes you can get cheaper capacitors in a bigger package with the same capacity if you don't need to save space. The DC derating is also worse in smaller packages. There is no free lunch...
I like to use resistors in MELF packages. The miniMELF 0204 package is basically the 1206 size. It is easily solderable. The 0207 MELF is huge in comparison and also really easy to work with.
The stencil and a paste are a way to go but you also need a reflow oven. I use a rebuilt toaster oven but it is another piece of specialized equipment you need. Or just order the assembly service if you feel lucky.
Be aware that the physical size also affects parameters like a maximum voltage (resistors and capacitors) or capacity in caps and hence the price. Sometimes you can get cheaper capacitors in a bigger package with the same capacity if you don't need to save space. The DC derating is also worse in smaller packages. There is no free lunch...
benny_profane
Well-known member
Not necessarily. Ref above for concerns about smaller packages. You must ensure that the voltage and power rating are sufficient and be aware of possible loss of capacitance.
szukalski
Well-known member
If you’re not used to Git then you’ll need to go to each file individually and “View raw” which will prompt you to download it. Then chuck the files in a folder and open that folder as a DipTrace component library.
Big Monk
Well-known member
benny_profane
Well-known member
What are you trying to do?This is already a pain in the ass...
finebyfine
Well-known member
You can find most transistors in SOT-23-3 and most op-amps in SOIC-8/14 although the market is, and has, obviously been moving towards smaller package sizes.
A pain in the ass when starting to do SMD boards is that different manufacturers sometimes call the same semiconductor package something different: SOT-23, SOT346, TO-236, SC-59 are all the same package, and those are just the ones I can remember off the top of my head. ditto SO8 and SOIC-8; and SOIC technically comes in two different widths. Digikey and Mouser are decent at consolidating these down to a non branded term, but LCSC less so. It's free to register for JEDEC - a standardization organization - which might be fruitful. Digikey, LCSC, and Mouser all make grabbing ecad footprints really easy but it's still more work than a TO-92 being a TO-92 being TO-92 being a TO-92 and if it isn't you can bend it into shape.
One thing I like doing with, semiconductors especially, on SMD boards is extending the pads outward from the component - diptrace usually has 3 footprints with differing sizes of copper pads for any given footprint (iirc nominal, least, most) and even still I find extending them saves some headache and gives some breathing room for assembly.
A pain in the ass when starting to do SMD boards is that different manufacturers sometimes call the same semiconductor package something different: SOT-23, SOT346, TO-236, SC-59 are all the same package, and those are just the ones I can remember off the top of my head. ditto SO8 and SOIC-8; and SOIC technically comes in two different widths. Digikey and Mouser are decent at consolidating these down to a non branded term, but LCSC less so. It's free to register for JEDEC - a standardization organization - which might be fruitful. Digikey, LCSC, and Mouser all make grabbing ecad footprints really easy but it's still more work than a TO-92 being a TO-92 being TO-92 being a TO-92 and if it isn't you can bend it into shape.
One thing I like doing with, semiconductors especially, on SMD boards is extending the pads outward from the component - diptrace usually has 3 footprints with differing sizes of copper pads for any given footprint (iirc nominal, least, most) and even still I find extending them saves some headache and gives some breathing room for assembly.
Big Monk
Well-known member
I was entertaining doing a mockup of my Pompeii Fuzz Face in the semi-classic board layout style of the Arbiter units and putting on the extra stuff underneath like the Dunlops.
Laundryroom David
Keyboard Cowboy 🤠
Do. Not. Sneeze.
swyse
Well-known member
I do this too, and a nice thing with this is if you use JLC to assemble your boards for you, you can use the EasyEDA component search to find "basic parts" which incur no extra fee, so I just ordered 10 boards today, assembled minus pots, LED and one filter cap and it was only $16.24 BEFORE my $9 coupon you get twice a month for SMT assembly. Shipping gets a bit pricy with preassembled boards, but 10 assembled boards and 3x10 of other PCB designs was $47 shipped DHL express so all things considered not too bad.
ozmuth
Member
sorry to drag up this thread, whats the recommendation with larger capacitor sizes for JLPCB assembly? eg. 4.7uf and above.
Stick with thru hole and hand do those? Banks of 1uf capacitors in parallel? I can see some 0803 packages in those sizes but not feeling confident they will be up to the task.
Stick with thru hole and hand do those? Banks of 1uf capacitors in parallel? I can see some 0803 packages in those sizes but not feeling confident they will be up to the task.
PedalBuilder
Well-known member
I stick with through hole for any caps that are: (1) electrolytic, or (2) in the audio path.
vigilante398
Authorized Vendor
I personally use 0805 for values up to 10uF for low voltage and go to 1206 or 1210 for capacitance 22uF and above, or voltages 250V and above.
