breadboard to prototype to PCB

RICoder

Once one gets to the point where they have an operational device on a breadboard with wires all over the place...what do you do with it to build your device?

I'm thinking I may grab a couple of the proto boards for the propeller just to have them anyway and use that as an interim step, but I'm thinking now about printing up the boards and building my little device, and that leads me to some questions.

The biggest one in my head right now is what style of chips to use. There's DIP (which is everything I have), then there is that smaller pin setup (2mm) and then there is surface mount (QFN / QFP). Perhaps an simple explanation of the pros and cons would be nice here.

Does it make sense, if one were to want to build 3 or 4 of a thing to go out and find/buy the surface mount (or smaller pin setup) versions of a chip? Is it possible or desirable to use DIP (the DIPs are so big)?

I'm pretty confused on this matter and would love advice before I make a decision and blow a ton of money and wait a week for delivery only to find out I made the wrong choices.

Post Edited (RICoder) : 2/3/2009 3:41:35 AM GMT

Franklin

Part of your answer will depend on the finished size you want. If you have room then dips are easy to work with but if you want small and need more pins (some chips have more pins available in the compact sizes 'because they can' go with the smaller packages. If you take your time you can connect surface mount devices, it just takes more care (much more sometimes).

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen

Timothy D. Swieter

What parts you use will also depend on your abilities. If you haven't soldered much and aren't ready to tackle surface mount parts, then stick with through hole. If you are just learning and doing your first couple PCB and design then it might be best to stick with parts you have so you can learn.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto for SunSPOT, BitScope
www.tdswieter.com

Craig Eid

Determining the package style will be dictated to a certain extent by the semiconductor manufacturers as they continue to shrink the size of the die and reduce the size of the packaging beause it is more economincal. Many parts, including the majority of sensors, are available only in surface mount.

Adapters are available for SOIC and SOJ parts to convert then to a DIP outline for breadboarding - I have attached a·link for an Aries SOIC adapter - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=A322-ND.·With a bit of practice and patience you should be able to solder an SO part but soldering QFN and related small packages requires more hardware. I use a hot air system and solder paste to solder and rework the smaller devices. These systems start at $250 and can easily exceed $1,000.



Craig

ElectricAye

Speaking as a newbie, I have found that when I try to solve all my electronic problems in one prototype, I usually end up disappointed and frustrated. So I've adopted an iterative approach that employs a "quick and dirty" prototyping technique. Namely, after I do a sanity check using solderless breadboards, I graduate the design to a breadboard that has a ground plane and solder everything together. The ground plane is needed for my application but it also saves some time (and wires) when soldering to ground. I've gone through several iterations of soldering my designs and testing different things, and now I'm looking at designing the PCB version. By going through all the hassle of soldering onto breadboards, I think I have a better feel for how to lay out the board when it comes time for the PCB.

Generally speaking, I noticed that when I was trying to "get it right the first time" I was not learning as much or as fast. By kluging up lots of circuits and making lots of mistakes (and observations, too), I found I learned the most. You might feel like you're wasting parts and labor this way, but I took my inspiration from the first rocket scientists. They knew that each test flight was going to crash and burn, but they cranked them out as fast as they could, instrumented each one as best they could, and learned as much as they could before the thing blew up during flight.

That said, you might also consider the PropStick USB version. It's the same size and pins as the DIP but it has the clock, volt reg, eeprom, and Prop all crammed onto one stick, along with the USB plugamabob.

my 2 cents worth

RICoder

Good stuff, and I am with you completely ElectricAye. I actually have the PropStick USB already, and I have used that exclusively to test my designs on a solderless breadboard. Now I want to graduate to the PCB, and I came to the conclusion yesterday that I ought get some perforated boards and try that first, so I did, and now I'm working on that step before I get a board printed.

What I'm finding is my challenge now is:
a) figuring out how to solder jumpers from one pin to the other.
b) finding the proper DIP plugs to use for the multitude of ICs I'll be using. (its quite a large design)

Any help on a) would be great. Also where you got a perf board with a ground plane on it would be nice to know [noparse]:)[/noparse]

I'm basically building up a cart here and at sparkfun with all the bits I think I'll need (and multiplying by 2 so I have extras) as I make a schematic/board design in Eagle to make sure I don't miss anything. In the end I should probably be able to get away without having to solder any of the ICs or MCs to the board...we'll see.

ElectricAye

RICoder said...
....Also where you got a perf board with a ground plane on it would be nice to know...

RICoder,

I got the prototyping board with ground plane from Digikey:

search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=438-1052-ND

The picture doesn't show the gold ground plane on the other side. The holes are plated thru-holes so it's nicer to work with than the foil types, which only cover the surface of a board on one side. My particular one was 4x5 inches but they have ones much larger. One thing to keep in mind: the gold plane acts as a heat sink, so you must make sure the gold is clean and gets a good heat so the solder actually bonds to it. They have non-gold versions, but they aren't much cheaper.

As for soldering from one pin to another - I feel your pain. Sometimes it seems like I have to melt down half a roll of solder just to connect two adjacent pins. (And yet unwanted solder bridges can appear elsewhere almost magically How is that possible???) If you figure out a good way to do that, please let me know. By now somebody should've invented a little do-hickey that slips over the pins and channels the solder just where it needs to be.

uxorious

You can use buss wire to bridge neighboring pins (or leads off of a resistor). Just cut a small piece and hold in place with tweezers. Makes it easy to remove if necessary also, since you can "flick" it off with the tip of an iron.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
~~ dRu ~~

RICoder

I poked around at a bunch of soldering tutorials, and finally got some ideas for bridging the gaps. I found it CRAZY that all but one of the many tutorials I saw don't even think to address it.

Anyway, this guy said you should push the jumper wire through from the top (like a component) and just cut it long enough to touch the pin you are connecting to, and then solder.

kamelorox

As for prototype house for pcb, it is always a tough question to answer. I tried with pcbfinpo, the quality is nice and I've tried twice already with them and once with pcbwing. Anyone has similar experience? If better and cheaper, please list them below. http://www.pcbfinpo.com/quote Thx.