45 replies to this topic

[pyromaniac303]

I see your point Trevor, they're not the most robust connectors in the world however they're cheap and readily available anywhere, so if you forget your cables at a display site just make a dash to your local Maplin/Currys etc.

 

For that reason however I am leaving considerable blank area (i.e. no copper) for those that wish to redrill and mount their favourite connectors. The 3.5mm connectors I'm using are the panel mount type, but mounted on the board its self and wired (2 per box, both in and out linked internally). It will probably make more sense with pictures when I get the V2 prototype boards in. I am holding off ordering boards until I get all parts including boxes to confirm dimensions - datasheets rarely 100% match real life dimensions!

 

1000x 4 way speaker connectors have arrived, and I shall be drawing up designspark footprints for them over the weekend after measuring a good handful of them.

[whoof]

How is this going ?
Been quiet for a while.

[pyromaniac303]

Its still on the go, I had to wait for my 100 cases to arrive from China via sea-freight before I did the next PCB layout, as I wasn't going to draw up the board outline without measuring a sample of them. They came in a couple of weeks ago, got near enough all the parts required now excluding a couple of passive parts which I can pick up on next day delivery from Farnell, and have been playing around with a few ideas in code to try and make things run smoother.

 

I will probably order just 5 of the next iteration of boards as I'm sure there will be some improvements to make, so it still has a way to go before I can sell them.

 

Also been testing out manufacturing techniques, I etched some solder paste stencils from copper sheet the other day and used them to reflow solder a PCB so it should greatly simplify populating the board.

Edited by pyromaniac303, 11 July 2014 - 04:29 PM.

[whoof]

 
Also been testing out manufacturing techniques, I etched some solder paste stencils from copper sheet the other day and used them to reflow solder a PCB so it should greatly simplify populating the board.

Interesting, i have tried this with 3 thou copper and 2 thou ally (using peroxide etch).

Both cases i found too much past applied resulting in bridging.

Any tips you would like to share ?

[pyromaniac303]

Interesting, i have tried this with 3 thou copper and 2 thou ally (using peroxide etch).

Both cases i found too much past applied resulting in bridging.

Any tips you would like to share ?

What package sizes were you using? Also what are you using to block the etchant from the reverse side of the stencil? For mine I used enamel paint on the reverse side, then toner transfer on the front face, and touched up any odd bits with permanent marker under a halogen lamp so I could see any reflective exposed copper.

 

Sometimes helps to reduce the aperture size by a percentage if you have bridging problems, but I think if you are using anything smaller than TSSOP/MSOP or the really fine QFPs you're going to always end up with a couple of bridges unless you go for a laser cut stencil with clean walls, as the etching process makes them slightly rounded. I still had a couple of bridges but nothing that couldn't be cleared up with braid, it cut build time by 1/4 compared to hand-build, and also made it possible to use some QFNs with underside paddles.

 

I did some rapid fire tests last night on an old version (hardware 1) slave and was happy with the results: http://youtu.be/PUNd...eTuHX2Sui6Y5J_w

[whoof]

What package sizes were you using? Also what are you using to block the etchant from the reverse side of the stencil? For mine I used enamel paint on the reverse side, then toner transfer on the front face, and touched up any odd bits with permanent marker under a halogen lamp so I could see any reflective exposed copper.
 
Sometimes helps to reduce the aperture size by a percentage if you have bridging problems, but I think if you are using anything smaller than TSSOP/MSOP or the really fine QFPs you're going to always end up with a couple of bridges unless you go for a laser cut stencil with clean walls, as the etching process makes them slightly rounded. I still had a couple of bridges but nothing that couldn't be cleared up with braid, it cut build time by 1/4 compared to hand-build, and also made it possible to use some QFNs with underside paddles.
 
I did some rapid fire tests last night on an old version (hardware 1) slave and was happy with the results: http://youtu.be/PUNd...eTuHX2Sui6Y5J_w

Qfps are the problem mainly , im etching from both sides to reduce under etch.
Sometimes the bit between pads goes though.

Laser stensils are just to dear.

[pyromaniac303]

Qfps are the problem mainly , im etching from both sides to reduce under etch.
Sometimes the bit between pads goes though.

Laser stensils are just to dear.

 

What method are you using to align both sides of the artwork? If the pads are going through it may be a registration problem.

 

I have seen some reasonably priced kapton stencils for $25US here: http://ohararp.com/p...stencil-8-5x11/ they may do the trick for short runs, I was considering it myself but can't seem to find whether they ship to the UK.

[whoof]

I use a punch and registration pins.

I should have acess to a laser from next week or so, kapton sheet is very difficult to find at reasonable cost though , i am told i cuts crisper than the mylar stuff.

[Crazy Cat]

delete please!

Edited by Crazy Cat, 23 October 2014 - 01:48 AM.

[digger]

bit difficult using an old desktop PC in the middle of field.

[Crazy Cat]

delete please!

Attached Thumbnails

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Edited by Crazy Cat, 23 October 2014 - 01:48 AM.

[digger]

Crackers

 

If you are taking this route why not just buy a usb output board from vellemam and then use your tablet, to save using outdated obsolete heavyweight technology. Far easier and you can fire a show from your favourite spread sheet.

[Crazy Cat]

delete please!

Edited by Crazy Cat, 23 October 2014 - 01:49 AM.

[Arthur Brown]

My lappy is about five years old (still on XPpro) it has no parallel port. going out into the field to use a lappy old enough to have a parallel port is a retrograde step. 

[Crazy Cat]

delete please!

Edited by Crazy Cat, 23 October 2014 - 01:49 AM.