How difficult it is for hobbyist to work with SMD packages?

[milad1234]

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?

 

[123jack]

Some components have commercial carriers available to make SMD easier - it may be worth looking to see if
your components have such carriers available. My advice would be to go DIP wherever possible on open source.
Another possibility might be to design a daughter board for people to have made themselves or maybe
you could supply them yourself. Tools do exist for some simple SMD mounting but I've never been able
to use them succesfully myself. (Soldering bits etc) . I guess it depends a lot on what you are making
and what compnents are needed.

 

[c_mitra]

It is perfectly acceptable to use SMD resistors and capacitors and diodes. I need forceps for some of the modern stuff but my major problem is to read the writings on them...

It is a nightmare to solder some of the spider looking ICs with legs spread all over ...

Anything smaller than 0.5mm is difficult to solder by hand.

 

[Warpspeed]

SMD integrated circuits, or the half pitch gull wing types of chips are not too bad, but like many things, there is a trick to it.

It is a nightmare to solder some of the spider looking ICs with legs spread all over

Spot solder two diagonal pins to anchor the part to the board, and get it positioned exactly right, that might take a couple of tries.
Then just solder right over all the pins along one side with big solder and a big iron, so its all one solid solder mass. THEN you use solder wick to remove about 95% of the solder.
The solder between the pins will be sucked right up. If you do it right, a thin web of solder hiding between the IC pin and board, will remain in place.
The flux from the solder wick will run everywhere, but it also helps with the soldering operation, and its easily removed with flux remover and a toothbrush.

Using this method its possible to solder twenty pins down one side of a large chip perfectly in just a few seconds after a bit of practice.

Surface mount resistors and capacitors are readily available in the thousands, but trying to buy just a few surface mount components in odd not frequently used values can sometimes be difficult. For that reason alone, plus the problem trying to identify parts with ageing eyes can be problematic.

My preference for home brew, or a kit, would be leaded components for just about everything except the ICs, and even then, DIP packages are to be preferred.
One big advantages of DIPs is that good quality sockets are available.
And that can make fault finding and repair vastly easier.

A lot of thought needs to go into an open source project, and it should be deliberately made as easy to build and repair as possible for people with limited skills.

 

[betwixt]

I would add that in the case of small pitched ICs, when designing the PCB, add at least one extra pad in line with the needed ones. It allows any excess solder to be 'flowed' on to it if swept with a soldering iron tip. It can make it more difficult to identify which are the real connecting pads so it is best used where there is a printed location on the board as well.

BGA packages are a compete no no. I do not know of anyone with hobby facilities to mount them and it takes an X-ray image to confirm the joints have melted.

My experience with devices with a base pad is that as long as the pad does not need it's own electrical connection, you can put a small dot of heat sink compound on it then sit it over a copper 'land' to conduct heat away. The other alternative if the board is double sided is to use an array of plated holes under the device and dot it with low melting point solder paste. Heating from the other side will flow the paste and make the joint. Unfortunately, solder paste is expensive and has a short shelf life so it may not be feasible to supply in small quantities in a kit.

Also be aware that SMD packages have soldering temperature profile which it is extremely unlikey a hobbyist could follow so the risk to the parts from overheating or expansion stress is much higher.

Brian.

 

[c_mitra]

Soldering is an art. The rest is mere stamp collecting.

 

[BradtheRad]

Since you're trying to choose one of the two formats, wouldn't it be great if there were a size in between?

Of course your decision is based on several questions:

* Which technology attracts customer interest today? Which direction is the future headed?

* Parts easy to obtain? Inexpensively?
* Easy to work with? (DIP wins over SMD)
* Easy to identify? (DIP wins)
* Wiring connections easy to make? (DIP wins)
* Easy to solder and unsolder? (Dip wins)

* How large a consumer market do you think your product has? Are these hobbyists? Novices? Professionals?

* Your product sounds like it introduces new opportunities ('hobbyists to create their own devices'). Can your product create a new customer base single-handedly? In one country? Worldwide?

* How likely is it that your product can be copied and undercut by a company on the other side of the world?

Speaking for myself, I have had an easy time working with the old-fashioned hardware (DIP). It's sized for handling by human hands. Soldering and unsoldering is easy. IC sockets are a convenience. I've made several projects using DIP devices, bare hookup wire, old-fashioned resistors & capacitors & transistors. They have wire leads. My parts bins consist half of components scavenged from junked appliances, and the rest purchased via mail order and Radio Shack.

Descriptions of SMD make them sound like a major headache to work with. Need to be held down while soldering. Once soldered, they're difficult to unsolder. Care is needed concerning excess heating time. Mistakes are easy to make. Easy to ruin components.

Miniaturization is a major advantage of SMD, of course. It goes with handheld games, test instruments, mobile communications projects... all of which are popular types of project.

 

[marce]

Been working with SMD since late 1980s, can be reworked and done manually, just need more/better equipment than a soldering iron and solder sucker, and training (which is required for any soldering) to learn the new skills required.....

 

[brushhead]

You can hand solder down to probably 0805 size, 0603 at a push. SOIC ICs are fairly easy too. I used a pair of tweezers to hold the component while I soldered with a small Iron. You can use solder paste and hot air from a Pyropen or similar.

 

[KamW]

With experience 0402, TSSOP TQFP. I have colleague who solder small count BGA !!! with simple soldering iron.
The main rule is – if you could see part, you can solder it
The most important question is what would be experience of people you work for.

- - - Updated - - -

0603 it is standard size for our students for hand solder

 

[Palpurul]

I didn't have any experience with soldering SMD components in the past. In my internship I had to solder some 0805 parts to build a prototype after a few tries using a tweezer it became easier and easier. I think a dedicated hobbyist can definetely solder passive SMD components, but I am skeptic about chips with lots of pins and narrow pitch, it really depends on what the chip is.