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TOPIC: Halloween Lighted Skulls - Revisited

Halloween Lighted Skulls - Revisited 3 years 10 months ago #17483

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Jon Chandler wrote:
What cave have you been living in Hop? I've been saying this for the last several years at least!
Why my MAN CAVE of course! lolJon Chandler wrote:
Most of the cheap boards from China appear to come from the same fab based on the lot code ID they screen on each board.
I noticed that on EEVBLOG about the lot code ID. Irritated David Jones big time. I do not want that at all.

I got enough info from ya to research this. I know you posted this before, but I certainly was not ready, and my memory is not what it use to be. This is fantastic news!!! I was envisioning spending $100-$150 for 10 boards and was timid by that. Even with shipping, $20+ for 10 100mm boards is amazing!!! Now I just need to go after software. I don't mind paying for a better tool, I just want to use what most people prefer. So long as it is reasonable. Do you have a recommendation? And if you posted THAT before, just let me know and I will go digging.

Whatever board design tool I use, I hope it has standards settings. When David Jones talked about tooling holes and those visual marks, I worried immediately about where to place them, the standard for location, size, etc. The boards I need are simple, but since the price is so good as you suggested, I can envision having some made that allow me to use more wonderful SMD devices.

Oh wow, now I need to plow into solder paste and using a heat gun to mount this stuff. This is all RACING BY ME. I feel like I'm in an accelerator! hehehehe

Halloween Lighted Skulls - Revisited 3 years 10 months ago #17484

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I see that Smart Prototyping offers a stencil for an extra fee. I read about making a reflow oven here a couple of years ago. I think I will go after that! Sounds like fun!!!

Halloween Lighted Skulls - Revisited 3 years 10 months ago #17485

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Dave shrieks about a lot of things, some more justified than others.

For the most part, the lot code is going to be small and inconspicuous, but it depends on the person processing the board. Here's a picture of a board that was close at hand. See the lot code?

Attachment 20151104_101106-1-800x526.jpg not found



Let me zoom in to help you see it.

Attachment 20151104_101126-1-800x767.jpg not found



See the lot code? It's inside the IC footprint. When the board is assembled, no one will see it. Most of the time, they're pretty good at putting it someplace where it won't even show.

I remember Dave was complaining about this on a board he used as a front panel on a box. In that case, appearance is critical and there was no place to hide the lot code.

Regarding stencils. For SOIC-pitched parts, a stencil may not be necessary. These can be hand soldered with a little practice, or with hot air and solder paste applied with a syringe (but it does take some effort to squeeze out the paste by hand!). For fine-pitch parts like the TSSOP pictured on this board, I found out the hard way that a stencil is a must! Solder paste simply will not move through a needle small enough for these pads. The smallest blob you can get covers more than one pad.
Last Edit: 3 years 10 months ago by Jon Chandler.
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Halloween Lighted Skulls - Revisited 3 years 10 months ago #17486

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Thank you Jon, that is very good information! I will most likely be trying SOIC to start. This bumps me up a step from through-hole and will give me some practice with my heat gun. I won't be doing any panels as of yet. Most of what I want to do will just need a small enclosure as they will be interface-type stuff.

I'm excited about SMD transistors, caps, and resistors though, and being able to scale this stuff down. They are cheaper too. :)

I am trying out PCB software now, starting with PCBWeb Designer. I already ran into a wall when I tried to pick from 2N2222 transistors. They all came up with a custom design thing which surprised me. Perhaps I have a setting wrong. The software exports Gerber files though, and it gave a version number for the protocol. I will have to research that.

I know all this is off-topic, but a great thread for a source of info for me, and maybe others. Thank you Jon for indulging me!

Halloween Lighted Skulls - Revisited 3 years 10 months ago #17487

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I use surface mount when I have to or it's more convenient. Many chips are only available in SMT (ever & ever smaller!) or I need SMT for the space.

On a board I did recently with 32 LEDs, I could have just as well used 3mm through-hole. I used SMT LEDs because getting through-hole LEDs installed vertically to the board is a pain in the butt.

Halloween Lighted Skulls - Revisited 3 years 10 months ago #17488

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Yep, and these paneled WS2812b's I get (100 per panel) are installed on little boards that have SMD pads. A board could be designed to arrange these things anyway I want. The only problem though is the PCB real estate that is wasted as the mounting frame. But for this application, the light pods that are inside a prop, this is definitely the way to go. I'll be happy as a clam if I never have to solder wire or a header to these pads ever again.

Hey, what is the preferred heat gun temperature for solder paste work by hand?
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