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A kit with surface mount ICs, would you be wary of building it?

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blueroomelectronics

Well-Known Member
I've avoided using surface mount parts in my kits because I'm concerned my customers may not want to tackle the difficulty.

That said I'd like to use a few surface mount ICs in the next kit. It's trivial to solder an 8 pin SOIC, very simple actually just a little tape and patience works great.

As for larger SOIC not too bad as long as you tack down one corner and tape the IC in place. Solderwick is handy for soaking up excess solder.

But TQFP is another story, you have to get it lined up perfectly and you will need solderwick. They are also very difficult to reposition once you solder them to the PCB. 64 & 80 pin TQFP can be a chore.

Comments?
 
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Pommie

Well-Known Member
Most Helpful Member
I can do SOIC. Anything trickier I've not tried. If you produce a video demonstration showing how easy it is, then I'm sure I would give it a go.

Mike.
 

Chippie

Member
I think you may be prone to too many device failures due to folk not being adept to smd soldering....Shorted pins, dry joints,ics damaged by overheating...

I've reworked smd in the past and it aint easy...Trying to solder 0805 components is diificult unless you have really good eyesight and I dont.. I had to add some components on an R/C receiver and needed to use a magnifying glass to solder the devices........:(
 

Wp100

Well-Known Member
Hi,

I've soldered for a good few years and found smd a pain to get used to, although with practice you do get better.

As for someone buying one of your kits, I would have to assume the majority will be beginners to soldering and smd seems a step too far, I would say.
You are then expecting them to buy extras like a suitable tip for the iron and a flux pen etc.
I'm sure standard parts would be a challenge for quiet a few of your users never mind trying to deal with smd sizes.

I would have thought for your kits it would be possible to have the smd parts pre soldered or at least the option when buying to request that they are pre soldered .

hth
 

blueroomelectronics

Well-Known Member
Well one part in question is the LM75 it's a SOIC part and with only 8 pins is pretty easy to solder. Pins 5 thru 8 all go to VDD so they're hard to mess up.

Just like TTL ICs are disappearing so is DIP in many new parts. I was thinking of having 2 (SOIC) or 4 (TQFP) holes drilled in the PCB at the sides or corners that you would insert stiff wire to "cage" the part before soldering. Just an idea haven't tried it.
 

DSGarcia

New Member
There are a number of great videos on YouTube that show the process of soldering SMDs using a number of different techniques. Perhaps you can label your kit as requiring an 'advanced' skill level and provide links to a few of the best videos (or even better, as was already mentioned, produce your own that shows the complete assembly of the kit). I would not be afraid to try such a kit (if I was really interested in that kit); it would be a great learning experience in getting started with SMDs. The quality of the PCB board provided will be important.

Depending on your design and if the board is single-sided, you can also suggest the "electric griddle" technique as an option for those too timid to try something more complicated.
Dale
 

Pommie

Well-Known Member
Most Helpful Member
One thing to keep in mind is that a kit aimed at an electronic hobbyist is more acceptable in SM. A kit aimed at Joe Public is doomed to failure.

Mike.
 
Find a pcb board house that will also solder down the tqfp for you. I had heard somewhere, and sometime back, that they charge .02 a pin? It would be a stretch to think that mere mortals would be able to stick one down.
 

DirtyLude

Well-Known Member
If you have trouble seeing, get some cheap drugstore reading glasses. They're just magnifying glasses that are more convenient.

I really can't comment, because just about everything I do, other than headers is SMD and I prefer the ease of an 0603 part over fiddling with a thru hole part any day.

QFP are not hard for me, but trying to see it from someone who is starting from little SMD experience straight to QFP might be a little much. Something like this would have to be marketed to intermediate amateurs rather than beginners.

It's hard to avoid QFP or SOP parts now and its only going to get harder so it's probably better to get the learning curve over for most people.
 

be80be

Well-Known Member
But TQFP is another story, you have to get it lined up perfectly and you will need solderwick. They are also very difficult to reposition once you solder them to the PCB. 64 & 80 pin TQFP can be a chore.
There not that hard tack three corners and you got it licked just 1 pin on three corners and it easy to do.
What I find hard is seeing them pins LOL
 

blueroomelectronics

Well-Known Member
Thanks all, I like the presoldered TQFP as an option. Should make it less scary for folks who don't want to attempt soldering such a device. Another option was a Schmartboard made PCB but this will increase the cost of the PCB.

kits in question are
Cricket: RF thermostat (LM75 SOIC) (PIC16F917 DIP or TQFP) battery operated I wanted the TQFP because it makes mounting a 3xAA holder easy on the opposite side of the PCB.

Ladybug: Ethernet with relays & inputs. The PIC18F67J60 is a 64 TQFP IC and I'll probably use a Schmartboard or presoldered TQFP in the kit.
 

DirtyLude

Well-Known Member
What I find hard is seeing them pins LOL
Get the reading glasses. Something like 2.75x or even 3.00x if they are available. It helps tremendously and are easier to work with then those large bench magnifying glasses.

Also, a suggestion to anybody working on SMD, but dealextreme.com has some really nice tweezers for cheap. I like these ones, but if you search "tweezers", there are plenty of options.
DealExtreme: $2.30 WeiTus Stainless Steel Precision Angled Tweezers

While you're their, you can get the 10X loop lens to check fine detail. Don't bother with the 16X one, it sucks.
 

Brian Hoskins

New Member
Personally I'm used to working with SMD parts and I actually show a preference for them with my own projects because it means I can produce my own PCBs without having to concern myself with drilling lots of holes.

I wouldn't be put off by a kit that had SMD parts.

Brian
 

blueroomelectronics

Well-Known Member
Well the Cricket will be the first with at least the simple to solder SOIC 0.050 LM75 and eight optional SOIC I2C EEPROM's

If I can squeeze the design down to a 28pin 16F916 I'll use the SOIC DIP

The 3xAA powered Cricket
I/O 16F916 pincount 24.5 available
16 LCD
2 I2C (LM75 or SHT11) & EEPROM
2 433 MHz / 315 MHz TX module & power control + TX LED
2.5 ICD/ICP & 3 pushbuttons

That could work with 2 pins left, possibly for a latching relay, 32kHz crystal, light sensor or 1wire port... Of course the larger 16F917 40pin DIP or 44pin TQFP could accommodate all those but I'd like to avoid the TQFP on this initial kit.
 
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crutschow

Well-Known Member
Most Helpful Member
It might help if you sold an SMD kit that would include the tools needed for mounting SMD parts, perhaps including a small tip soldering iron of the appropriate wattage.

As others have noted, everything is going surface mount and hobbyists will have to eventually learn how to work with them if they want to continue building electronic kits.
 
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