Making your own pcb's.

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racemaniac
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Making your own pcb's.

Post by racemaniac » Fri Jul 14, 2017 11:33 am

I'm wondering how you guys make your own pcb's, where i currently am (i started doing it fairly recently):
Designing them
I use KiCad to design my pcb's. I chose it since it's free, and as i started fairly recently, it was already at a point where it seems good enough.
for me:
pros:
-free
-the UI is ok (not perfect, but good enough)
-easy to find tutorials/help
-easy to make your own footprints
cons:
-still has a few too many stability issues
-still needs some maturing, like the new OpenGl canvas that is lacking some features and then you have to switch to another older canvas to do certain actions

Having them built
Atm i use dirtypcb's.
my experience with them so far is good.
pros:
-they allow free panelization for 2 layer boards
-they go down to 6/6mil spacing/track width (also slightly smaller vias compared to other cheap board houses)
-even if you don't exactly respect their requirements, if you don't exaggerate they'll still make it. No pingpong because 1 trace is a bit too small, or a silkscreen line is a bit to thin or... (i hear that with some boardhouses it's not easy if you're a beginner)
-all colors cost the same
cons:
-a bit more expensive than the real cheap ones

Soldering them
having QFN components on my boards, this is also a challenge
Solder paste
Yesterday i received a batch of Loctite GC10 solder paste, and my first test seemed *very* encouraging :). First attempt at 2 qfns seemed to go very well. I have yet to do an optical inspection of it (made myself a solder cam so i can see the small details), and check for shorts, but at least everything is connected and i can program the stm32 (i ran a small test program that just toggles all connected pins).
stencils
stencils are becoming cheaper, but when i discovered i could buy a 150€ silhouette portrait cutter, and cut my own stencils on overheadprojector slides, i didn't hesistate :). Very glad i bought it, i can now quickly make my own smd stencils whenever i need them (like for experimenting with the solder paste i'm currently making stencils with just the qfn parts as that is what i'm most focused on now, all the other things are easy to solder).
More info about it can be found here: http://dangerousprototypes.com/forum/vi ... =68&t=5341
there is a gerber2graphtec python tool you need (it makes the cutter work more precise). and it's giving me great results even on the qfn pads with 0.5mm pitch.
the actual soldering
i've got an aoyue hot air smd reworking station that i'm very pleased with. But i'm now also using the skillet method (just putting the pcb in a skillet on the fire in the kitchen, works remarkably well and as cheap as can be XD. using an old skillet i hadn't thrown away yet, and pleased with the result).
i'm considering building an own oven, but as the solder paste is leadfree, finding a toaster oven that can go warm enough may be hard :s.
Seeing as i'm going for small pcb's, this actually seems like a great idea: http://hackaday.com/2017/07/13/a-bright ... soldering/

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mrburnette
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Re: Making your own pcb's.

Post by mrburnette » Sat Jul 15, 2017 3:54 pm

racemaniac wrote:
Fri Jul 14, 2017 11:33 am
<...>
But i'm now also using the skillet method (just putting the pcb in a skillet on the fire in the kitchen, works remarkably well and as cheap as can be XD. using an old skillet i hadn't thrown away yet, and pleased with the result).
I have read that using clean white sand in the bottom of the skillet provides better temperature control. No personal experience in that area but I swear by my hot-air rework station.

Ray

zmemw16
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Re: Making your own pcb's.

Post by zmemw16 » Sat Jul 15, 2017 5:05 pm

it maybe self evident that it needs to be dry sand, however you might want to keep a few silicate packets in with the sand :)
stephen

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Just4Fun
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Re: Making your own pcb's.

Post by Just4Fun » Mon Jul 17, 2017 7:38 am

About solderpaste and hot air gun...

I usually use a cheap solderpaste syringe (no stencil), and often is a little "outdated" too...
I found that with a "soft" PCB preheating made with a common hairdryer for a couple of minutes before apply the solderpaste, it helps a lot the adhesion to the pads and the control of the right quantity.

zmemw16
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Re: Making your own pcb's.

Post by zmemw16 » Mon Jul 17, 2017 1:00 pm

you can buy 'sets' of assorted diameter needles to fit the half twist on syringes.
you can also buy bags of syringes as well.
pots of paste are more economic as well.
remove the needle and a suitably sized rod can push the plunger back a fraction or fully out with only gentle tension else it pops out of the head. the head can flip and then its a fishing exercise.
try adding flux, couple of drops at a time to loosen the mixture, mixing is fun.
much easier if plunger is ejected or it's a pot.
my spare pots are wrapped in multiple layers of cling film and in the freezer.
stephen

victor_pv
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Re: Making your own pcb's.

Post by victor_pv » Thu Oct 19, 2017 6:36 pm

Reviving this old thread since it's all related.

Does anyone has link to a good cheap solder paste syringe for a few boards?

And has anyone successfully made a reflow oven out of a toaster oven?

I'm about to try the skillet method, but don't want to "cook" the boards if there is some better way...

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RogerClark
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Re: Making your own pcb's.

Post by RogerClark » Thu Oct 19, 2017 8:12 pm

I have not had any luck with ovens.

Bought a normal toaster oven, but found that it does not heat up fast enough.
Looking at how people manage to make a toaster oven work as a reflow oven, they need to do a lot of expensive modifications.
e.g. cover the interior with expensive gold , heat reflective tape, add an additional heater element

So I decided to buy one of those cheap Chinese made reflow oven ( I think its called a T962), but it was useless.
Heat control was terrible.
So, I reflashed the firmware with the open source version that someone wrote for that oven, which also allowed control via serial, and had support for multiple external temperature probe interfaces, and used the vent van to aggetate the air.
( fitted two new Maxim thermocouole interfaces to improve the temperature control)

But the internal temperatures still varied widely between the 2 probes, so it maxe a big differnce where you put the board e.g. hot spots and cold spots in the oven.

I saw that somone did a further modification to the oven to fit an internal fan blade, driven from a motor above / outside the midde of top of the oven, but I dont have a lathe or the other machines needed to make this assembly, so I gave up...


i did have one mad cap idea...

Why not use a hot air paint stripper to blow hot air into a toaster oven. They are quite cheap and put out air that should be hot enough, plus yiu can get ones with built in variable heat controls, and possibly ones where you can also vary the air speed.

This could potentially get around the problem with uneven heating and lack of heating power which all these ovens seem to have in common

victor_pv
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Re: Making your own pcb's.

Post by victor_pv » Thu Oct 19, 2017 8:31 pm

That idea doesn't seem so mad to me... it makes sense. You dont even need an oven, or a functional one to start with, just a good enough enclosure.
I'll do some search in google to see if someone has experimented with that.

zmemw16
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Re: Making your own pcb's.

Post by zmemw16 » Thu Oct 19, 2017 9:19 pm

might be an idea to use a "fan oven" fan, would tend to mix the air inside the oven and already temperature rated ?

the trick will be finding one without the cost increasing 'brand' name, aka go faster stripes :D

stephen

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RogerClark
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Re: Making your own pcb's.

Post by RogerClark » Thu Oct 19, 2017 10:07 pm

I think a fan is essential.

The problem is most domestic ovens do not heat up fast enough. I know the oven in my kitchen seems to take around 10 mins to get to 220 deg, which is far to slow.

The oven needs to have the ability to get to almost the reflow temperature in a reasonable time frame, e.g. perhaps a min or two, but crucially it also need to be able to quickly ramp up to the melting temperature and then reduce the temperature after flow has occurred.


This one seemed to fit the bill quite well

https://www.bunnings.com.au/ozito-2000w ... n_p6290265

Because its variable heat

But As I suspect both the motor and the element would need to have speed controls, its probably more economic for me to buy this on

https://www.bunnings.com.au/xu1-2000w-c ... n_p6290580

Which is cheaper, and add the external controls.

4Kw dimmer controllers care cheap

http://www.ebay.com.au/itm/4000W-AC-220 ... 1849472710

But they would need the triggering control e.g. a BluePill plus some optos

Not sure what to house the thing in.

A toaster oven is probably too big

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