Author Topic: How difficult it is for hobbyist to work with SMD packages?  (Read 12976 times)

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Offline milad1234

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How difficult it is for hobbyist to work with SMD packages?
« on: April 28, 2016, 12:44:08 am »
Hello,

I am working on an open source project that will be released for hobbyist to create their own devices at lower cost.
We have to make a decision to design the PCB and select components for SMD packages or redesign for DIP packages.
I am not able to find many options for DIP components.I know DIP packages are getting harder to find these days. A few years ago SMD wasn't common among hobbyist as they did not have the tools to deal with SMD chips.

As SMT tools have become cheaper and it's becoming easier to use surface mount SMD reflow soldering, how difficult is it to build a home project with SMD parts for hobbyist if DIP package is not available?

So in short,how would people deal with it if only SMD parts of available for the chip they need?
 

Offline CatalinaWOW

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #1 on: April 28, 2016, 01:00:56 am »
Use large parts, avoid BGAs and fine pitch packages and you will be fine.  Basic answer, if you can do it with a fine tip soldering iron and a magnifying glass you should be fine.  If it requires hot air you will lose some.  If it requires an oven you lose more. 

 

Offline ANTALIFE

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #2 on: April 28, 2016, 01:07:01 am »
Yeah as CatalinaWOW said use larger components, most people I know are fine with anything larger than an 0805 in terms of jelly bean parts. As for IC's and LED's make sure that legs are easily accessible.

Offline milad1234

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #3 on: April 28, 2016, 01:10:24 am »
Use large parts, avoid BGAs and fine pitch packages and you will be fine.  Basic answer, if you can do it with a fine tip soldering iron and a magnifying glass you should be fine.  If it requires hot air you will lose some.  If it requires an oven you lose more.


Thanks for your response.We are thinking to use 1206 SMD Package type.Is it large enough?
 

Offline milad1234

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #4 on: April 28, 2016, 01:16:50 am »
Yeah as CatalinaWOW said use larger components, most people I know are fine with anything larger than an 0805 in terms of jelly bean parts. As for IC's and LED's make sure that legs are easily accessible.

Great! How about 28SOIC?
 

Offline EEMarc

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #5 on: April 28, 2016, 02:08:09 am »
SOICs are easy to solder. SSOP at TSSOP with finer pitch are moderately difficult without a good soldering iron.

I recommend using either silver or gold plated PCB for surface mount parts, particularly for finer pitch parts. The parts sit nicely on a flat surface. HASL will make them tend to shift off of the pads making it more difficult as the pads often have a rounded coat of solder on top for smaller pads.
 

Offline Dago

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #6 on: April 28, 2016, 04:25:00 am »
I've never had any issue soldering any SMD package (I've avoided BGAs though). Don't even need that fancy equipment to do it, good soldering iron, good tweezers, loads of flux and a hot air station (which cost like 50-100$ nowadays). Microscope is nice to have but depending on your vision not mandatory (I only have a crappy USB microscope that I very rarely use).
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Offline batteksystem

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #7 on: April 28, 2016, 04:29:45 am »
SOICs are easy to solder. SSOP at TSSOP with finer pitch are moderately difficult without a good soldering iron.

I recommend using either silver or gold plated PCB for surface mount parts, particularly for finer pitch parts. The parts sit nicely on a flat surface. HASL will make them tend to shift off of the pads making it more difficult as the pads often have a rounded coat of solder on top for smaller pads.

From my experience SSOP is also okay, it really depends on the pin pitch, the larger the better. I am experienced with soldering these tiny parts with solder wicks. I think this is no problem for hobbyist if they had the right equipment.

Offline ez24

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #8 on: April 28, 2016, 05:04:45 am »
Use the largest parts available
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Offline Ice-Tea

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #9 on: April 28, 2016, 05:44:00 am »
0805 is fine. 0603 is still possible, but at least I have a less than 100% succes rate with those. TQFP's the same issue: with some practice they are a definite possibility but don't expect to get 100% right.

Offline Siwastaja

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #10 on: April 28, 2016, 06:02:55 am »
Thanks for your response.We are thinking to use 1206 SMD Package type.Is it large enough?

It's too big, unless you really need it (power resistors, large caps).

You lose the benefits of SMD (dense integration).

Going beyond 0805 doesn't make it easier anymore, but more difficult IMO. Thermal mass increases. The easy part in soldering SMD is that the solder flows so quickly, due to small thermal masses, that it's not easy to fail in the way that many people fail through-hole components - not heating enough, or not heating all parts (pad + component lead) at the same time.

When designing PCB, don't connect pads directly to planes but use thin and long enough thermal reliefs, and a 0603 or 0805 SMD is actually easier to solder than through hole. The reason is that even without proper connection between iron, component and traces, any solder that melts will touch the trace and component, transfer heat and heat up parts in < 0.5 seconds, way before flux has burned away, providing proper wetting and solder in less than a second.

Going bigger increases thermal masses and also increases the risk of ceramic caps stress cracking when not solder just right.

IMO, 0603 is a very good size, even for a beginner. 0402 is too small for most beginners. 0805 is generous, and some beginners do prefer it over 0603.

0805 is really the sweet spot from the ease of soldering viewpoint, given properly designed PCB. Easiest component type to solder, ever. Beats through-hole.
« Last Edit: April 28, 2016, 06:07:17 am by Siwastaja »
 

Offline KL27x

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #11 on: April 28, 2016, 06:23:39 am »
Personally, I prefer SSOP over SOIC. But I agree, that might turn off a lot of hobbyists.

As far as the passives, I think 0805 would be just as good as 1206.... As long as you include about 4-5 extra pieces of each component. If you need one, include a cut tape of at least 5 (maybe not the more expensive caps/LEDs). And figure out a good way to package and label the kit.
 

Offline Siwastaja

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #12 on: April 28, 2016, 06:36:10 am »
Yes, if this is going to be a kit, definitely include a lot of extra passives. The beginner needs to be taught that SMD resistors cost 0.1 cents or less. No time should be spent finding "missing resistors" from the floor, or carefully counting the components. Provide a tape with 100 resistors if they need 10. That way, they'll accumulate some for their later projects, too.

Also, try to minimize the number of different parts. For example, you don't usually need a 4.7k pullup for one part and 10k for another; use 10k for both. Or a 120 ohm for an LED and a 47 ohm for a mosfet gate; use 120ohm for both.
 

Offline JPortici

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #13 on: April 28, 2016, 06:43:47 am »
"how difficult it is?"
it isn't, until smaller than 0603 for passives, qfn and smaller pitch for ics
you need a proper solder iron, that is.
 

Offline Siwastaja

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #14 on: April 28, 2016, 07:04:16 am »
Best tip is "chisel" type, 1.6mm to 2.4mm chisel tip width, something like this: http://www.vetco.net/catalog/images/XY-44-415404-1.jpg. Don't use the sharp needle type, which is a catch for beginners.
 

Offline Bud

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #15 on: April 28, 2016, 07:20:03 am »
0805 that is, but make sure the pads are big enough for soldering with a soldering iron. Some footprints in CAD packages are way too small and only suitable for hot air.
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Offline Kjelt

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #16 on: April 28, 2016, 07:30:22 am »
I am working on an open source project that will be released for hobbyist to create their own devices at lower cost.
We have to make a decision to design the PCB and select components for SMD packages or redesign for DIP packages.
I am not able to find many options for DIP components.I know DIP packages are getting harder to find these days. A few years ago SMD wasn't common among hobbyist as they did not have the tools to deal with SMD chips.
As SMT tools have become cheaper and it's becoming easier to use surface mount SMD reflow soldering, how difficult is it to build a home project with SMD parts for hobbyist if DIP package is not available?
So in short,how would people deal with it if only SMD parts of available for the chip they need?
Well reflowing at home, owning a reflow oven and solderpaste with syringe ($$$) is not that common, this forum is not a good representation of your target audience I guess.
However as pointed out above by other members, a reasonably good solderer could do 0805's components without too much problems if they at least have small enough solder and good iron.
But smaller smd ic's is as far as I am concerned a no go for standard hobbieists. They would short pins, and ruin your reputation with bad reviews before you sold many of them.
So what you see a lot is that companies selling kits with difficult to solder smd ic's make a halfproduct: a small converter pcb with the decoupling caps and some other needed small smt stuff on it (pull up resistors 0402, crystal or so), ready to go. Something else you see a lot if that the difficult ic's are already pre reflowed on the bare pcb, so the hobbieist already has the hard stuff taken care of and can do the more easy stuff himself. However that means you as a company have to prepare the boards and make the choice to be Rohs compliant or not etc. etc. Good luck.
 

Offline Jeroen3

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #17 on: April 28, 2016, 07:41:26 am »
SOIC and 0805 are easy. With a normal THT soldering iron (big chisel) and 0.5mm sn60pb40, add a flux pen and make it look better.

0603, TFQP and (T)SSOP require more patience. People avoid these because they are small, but the trick it to let the solder do its job. Surface tension of solder helps you. I have a big chisel soldering iron and can do TQFP and (T)SOP without issues. But I use paste and air method because this is much faster.
I've also seen people using hot plates (for cooking) modded with a PID controller to reflow boards.

With QFN you will need paste flux and hot air. These are really difficult because you cannot inspect them without optics.

Tip: use a camera to create a macro photo of your solder work if you don't own a microscope. You can zoom in using the camera. An iPhone camera is good enough.
 

Offline tautech

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #18 on: April 28, 2016, 07:43:03 am »
Personally, I prefer SSOP over SOIC.
Why?
Are they easier to drag solder?
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Offline Kjelt

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #19 on: April 28, 2016, 07:47:09 am »
People, AFAIU the target audience are the people that solder once/twice a year.
You can not expect them to do drag solder for the first time and be succesfull, you can not even expect them to have flux (worse they put hardsoldering copper waterpipe stuff on it and ruin everything).
They probably have a solderiron you plug into the mains directly.
 

Offline Kalvin

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #20 on: April 28, 2016, 07:54:00 am »
<snip>Microscope is nice to have but depending on your vision not mandatory (I only have a crappy USB microscope that I very rarely use).

Agreed. Even a cheap and crappy USB-microscope from eBay is handy. Some sort of stand or arm for the USB-microscope is also very useful. A good white (LED) light helps reading the markings.
 

Offline Siwastaja

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #21 on: April 28, 2016, 07:55:43 am »
So what you see a lot is that companies selling kits with difficult to solder smd ic's make a halfproduct: a small converter pcb with the decoupling caps and some other needed small smt stuff on it (pull up resistors 0402, crystal or so), ready to go.

I think the reason for this is that automatic pick&place&reflow is ridiculously cheap when done in large enough quantities (hundreds of kits sold, for example), and many people are afraid of hand-soldering SMDs, and anyway don't want to spend too much time on soldering parts. Hence, it makes business sense to solder in SMD devices and leave a few big components for the end user so that they feel like they did something for themselves.
 

Offline KL27x

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #22 on: April 28, 2016, 08:24:24 am »
Quote
Why?
Are they easier to drag solder?
Yeah, but only with a $500.00 microscope, lol. SOIC pins are so big, it takes a relatively enormous amount of solder. So you kinda have to slop on the solder and the first pin gets a lot. By the end, you are running dry. With SSOP, it's just one swipe, done, nice and even.

But this matters mostly for doing batch assembly. With SSOP, I can drag solder 6-12 20 pin chips without stopping. With SOIC, I need to stop to reapply solder every couple chips. Large SOIC chips are also borderline too big to see the whole chip under the scope. Larger IC's also means futzing with more tubes and trays. SSOP is very easy. MSOP even, but not too many of the chips I use come in MSOP.

Doing SOIC is actually quite annoying, once you are used to soldering the smaller pitch packages.
« Last Edit: April 28, 2016, 08:41:18 am by KL27x »
 
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Offline IanJ

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #23 on: April 28, 2016, 11:01:27 am »
Hi,

Eyesight is key........let's say you need to be able to focus 6" from target. If you can't, or are soldering extremely fine pitch then you need a magnifier hat. Microscope is not necessary. I have both but never use the microscope.

Something like these with interchangeable flip down lens.



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Offline MrSlack

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Re: How difficult it is for hobbyist to work with SMD packages?
« Reply #24 on: April 28, 2016, 11:05:44 am »
It's fine. If anything is a pain, it's not actually working with the packages, it's finding a suitable prototyping method.
 


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