SparkFun Forums

[oakgraphics]

Hello gang,

Probably a newbie question - but what is a good size for SMD/SMT parts on a pcb? I am looking for something that I can reduce the size of diodes, resistors, caps, on my pcboards at the same time something I can hand-assemble.

I am a hobbiest - for sure. So my budget is not great. But what would be good tools for it? (soldering gun/tips, etc.

I know the basic parts (I guess) like 0201, 0402, 0603, 0804,1206 (is that correct? Is there a sizing chart somewhere?) Seems like 0804 and 1206 are popular, but thier sizes seem large (expecially the 1206). So is 0603 the 'most popular' for it's size? Is 0402 too much of a pain to hand solder without bionic modifications?

If you don't hand solder them - what do you do? I have seen the videos on sparkfun for the reflow plate and toaster ideas and they look spiffy, but iffy for me at this stage. I suppose the more I do - the more that would look like the way to go.

[leon_heller]

I mostly use 0805, and 0603 occasionally. I use a Metcal soldering station with a 1/32 inch bent conical tip cartridge.

Leon

[mtwieg]

I'm comfortable hand soldering 0805, never tried anything smaller. For diodes, sod123 packages are pretty nice.

Hold off on the reflow and stencil method until you have prototyped it and worked out all the bugs in the layout. No sense in buying a stencil for every board revision.

[bigglez]

.....what is a good size for SMD/SMT parts on a pcb? I am looking for something that I can reduce the size of diodes, resistors, caps, on my pcboards at the same time something I can hand-assemble.

Greetings (No Name Supplied),

First time to SMD/SMT? Hand tools? 1206 is your best choice.

I am a hobbiest - for sure. So my budget is not great. But what would be good tools for it? (soldering gun/tips, etc.

Soldering iron with exchangeable tips. I use a MetCal.

I know the basic parts (I guess) like 0201, 0402, 0603, 0804,1206 (is that correct? Is there a sizing chart somewhere?)

It's a moving target. The industry creates new parts. There are some modifications to existing parts to cater for different assembly and rework techniques. Trying to memorize the system is probably not a good use of your time.

If your goal is to build something that works you can use any parts you can find. If your goal is to make a limited run (two or more) consider making life a bit easier by careful design. If you're going to do more than a couple of dozen of the same design consider farming it out to someone with production tools.

Seems like 0804 and 1206 are popular, but thier sizes seem large (expecially the 1206).

Really? What is your starting point? If you have been making prototypes or PCBs with TH (Through Hole) components then 1206 gives at least a two fold decrease in board area.

If you don't hand solder them - what do you do?

I use solder paste and a hot air gun ($35 for a year's worth of solder in a syringe that you store in the 'fridge, about $50 for the "hair dryer" style gun). I've done boards up to 100 x 150mm with around 200 components this way. There are some risks of localized heating distorting the board but with care this can be avoided.

Prior to that I use a small point soldering iron tip, and a slotted tip for removing 1206 parts. For ICs with quad pins (TQFP etc.) I used the drag soldering method with solder wick for clean up.

Comments Welcome!

[NleahciM]

I find the larger surface mount discretes annoying to work with. They don't fit as well in tweezers. I think 0603 is the perfect size - small enough that they don't take up too much space, but large enough that they are easy to see and solder.

I solder them with a normal pencil iron (Hakko 936-12) and the smallest diameter no-clean Kester solder. I've also used various paste techniques (hot plate, oven, hot air pencil). I find the hot air pencil to only be effective for rework. Otherwise, it is just too slow. Hot plates work OK, but you are limited to components on one side. Ovens are good as you can do both sides (one at a time), but I only use them when I'm making a number of duplicates of a board.

[Philba]

I find the larger surface mount discretes annoying to work with. They don't fit as well in tweezers. I think 0603 is the perfect size - small enough that they don't take up too much space, but large enough that they are easy to see and solder.

Interesting. I use forceps - 1206s and big tant caps are a breeze to manipulate. What do you do about ICs like SOICs - those have got to have tough if 1206s are hard.

[busonerd]

Hi - we at SparkFun use all 0603's when we can [0805's+ only in cases where we need a higher wattage /capacitance value than we can get in 0603s]

Personally, I prefer 0402's - to me, they're the perfect size, as I can pack tons and tons of stuff into a small area, yet they're still doable with an iron + tweezers + mag lamp.

Cheers,

--David Carne

[NleahciM]

Interesting. I use forceps - 1206s and big tant caps are a breeze to manipulate. What do you do about ICs like SOICs - those have got to have tough if 1206s are hard.

I have some reverse grip tweezers that work well for the larger discretes. I just don't like it as much. I wouldn't call them harder - just more annoying.

Chips I typically place by hand, then move into place by nudging them with my tweezers. If I'm using paste (not often) - I have to get creative. (vacuum tools, large grip pliers, the sky's the limit)

[pcbChallenged]

I am a frantic senior getting ready to graduate (if my project works) and am now dealing with the shortfalls of too much theory and not enough application. So, I have never really designed a pcb before ... but I've researched a lot and I'm going to give it a try. HOWEVER, research could go on forever when it comes to soldering. I have some components that are fairly small, but I can still see them fairly well and imagine that soldering them will be a bit tricky. I think those will be OK. The problem is that one of my components is a GSM modem that has a 50 pin molex connector with a pitch of .5 mm. YIKES. Luckilly, I don't need to connect to all of the pins, thank God. I don't have the number in front of me but I believe I have to solder around 20 at the most and the others can be left unconnected. There is a metcal rework station at school that I will have access to, but have no idea yet how to use. Do you think trying to hand solder would be a nightmare for that small pitch, or should I try to learn the metcal reflow station. Thanks for any help in advance.
Pam

[leon_heller]

Drag solder the leads using plenty of flux. I use a Metcal system with a mini-hoof tip, but you can use an ordinary iron.

Leon

[busonerd]

The technique I like is to pin down each corner, so that its aligned perfectly [make sure its perfect before going on to the next step]. Then I "blob" a lot of solder over all the pins - it usually looks like one continuous blob. I then remove all the extra with solder wick.

Cheers,

--David Carne

[RonnyM]

Look at the soldering tutorials on SF. They helped me considerably. I also purchased a Cuisinart convection toaster oven, and cook up my boards using nothing but a pretinned board,solder flux and the components. It works quite well, and saves lots of time.

[Azoore]

The technique I like is to pin down each corner, so that its aligned perfectly [make sure its perfect before going on to the next step]. Then I "blob" a lot of solder over all the pins - it usually looks like one continuous blob. I then remove all the extra with solder wick.

Cheers,

--David Carne

This is what I do. With a heaping of flux!

[pcbChallenged]

Thanks for all of the tips everyone... I'll let you know how it turns out. Another probably silly question... I'm doing a board that will be double-sided. I've never designed a board before ... I am very close to knowing all of the components I will need and am getting ready to attempt doing the layout. My question is one of my components is a GSM modem and it mentions that I should use a dedicated ground plane ... basically meaning that I might have to do a 4-layer board? A friend of mine said that I could probably get away with a 2-layer board. Does anyone think know of a novice style "PCB for dummies" online reference that I could consult if I do decide to attempt making a 4-layer board. I'm not sure if I understand the concept of a dedicated ground plane, and also a dedicated power plane. Can anyone break that down into simple-talk for me? Or reccomend a site that does? Also, does anyone else agree that I might be able to get away with using a 2-layer board? Thanks is advance for the help.
Pam

[bigglez]

I'm doing a board that will be double-sided. I've never designed a board before ... I am very close to knowing all of the components I will need and am getting ready to attempt doing the layout. My question is one of my components is a GSM modem and it mentions that I should use a dedicated ground plane ... basically meaning that I might have to do a 4-layer board?

Greetings Pam,

There are very few cases where a four layer (or higher count) PCB are required. Mostly these exist due to component density (not electrical performance). Four (or higher count) PCBs have the advantage that layers can be assigned to specific functions, such as a ground or power plane.

"Things should be made as simple as possible, and no simpler" Albert Einstein

A friend of mine said that I could probably get away with a 2-layer board.

Most likely! The module may already have a ground plane or metal enclosure that would take the place of a PCB ground plane. It could be that adding a ground plane requirement would stop the user (that's you) from routing signals or noisy power traces under the module and reducing it's performance.

I'm not sure if I understand the concept of a dedicated ground plane, and also a dedicated power plane. Can anyone break that down into simple-talk for me? Or reccomend a site that does? Also, does anyone else agree that I might be able to get away with using a 2-layer board?

Power and ground planes provide much lower inductance to and from the power supply and effectively limit or remove potentially harmful signals from being injected into sensitive parts of the circuit. They are very helpful in high current circuits (motor controllers, power converters, audio amplifiers, etc.). They are also found in RF circuits where matching and reduced transmission losses are required between components and connectors. In very weak signal applications (radios, instrumentations, GSM receivers) ground planes provide shielding and isolation.

(1) I don't know of any tutorials - much of this work is application specific and still a "black art"
(2) The module should come with an application note and sample PCB layout.
(3) Once you have completed the PCB design you can post it here for the collective wisdom of the group (before you commit to PCB fabrication).
(4) Many layout sensitive designs require more than one 'spin' - the first is often cut up on the bench for further experiments.

Comments Welcome!