Since there will be less glass to conduct heat, you should probably cover more area with copper when laying it out.
I just did a mod. where the driver had to sit under the pill, as sometimes done on SK-68s. A thinner board would have saved me some filing.
What is our collective experience on OSH Park’s removing copper from the edges of the board? We are all aware that this is normally done. They require a 15mil setback for traces, but since our copper pours are not really traces it’s standard for us to specify copper right up to the edge of the board. Somewhere along the line a little copper is removed in order to prolong the life of the router bits used to cut the boards. How much are we talking about? I’ve just checked several boards using a feeler gauge and to me it looks like less than 0.2mm in all cases.
If you didn’t get your answer elsewhere already, the cap was moved due to a problem with voltage boosting upsetting the MCU. Comfychair, with help from other members, explored this pretty thoroughly in the FETs and gate resistors - scope images thread. Since the thread is now devoid of pics, here’s a link that shows the pics with the posts: Oops - looks like I’m having a connectivity issue right now so I can’t finish renaming this at the moment. For now you can go here and click on the link with a size next to it.
It’s a part of the big fancy groupbuy that’s about to go to the ordering phase. So in a month or two we will either have a few hundred raving fans, or a few hundred angry customers.
Most likely a couple raving fans, a few hundred quietly content fans, and a couple dozen noisy, angry customers that will steal the show and try to make it look like a failure. :weary: I’m expecting to be one of the happy ones.
The thicker copper that oshpark offers now will wick away heat to the side better. Hmm, that could be interesting for ledboards too. There are many leds for which a dedicated board is not easily available, Nichia119, LuxeonZ, LuxeonC color line, to name a few. These can be made at Oshpark by using large poors to the side from the solder pads for heatsinking. Nothing for high wattage, any MCPCB will work better, but for low output builds it could work.
In my testing solder filled DTP works better than a normal fiberglass MCPCB does, but it is very sensitive to reflow and getting the right amount of solder (you need enough to fill the vias, but you don't want it to all be wicked away from the LED's thermal pad), as well as keeping the backside as flat as possible. Definitely usable for a hobbyist type situation, but definitely not for full-on production work. A copper DTP MCPCB is obviously superior, but getting them made in custom sizes is very expensive to get started (the initial setup and tooling is expensive!).
You all know where this is going . You can use this to program the tiny attiny25/45/85 MU MCUs. As usual, the spacing and via sizes are suitable for standard header pins. Like the other board, I have labeled the USBASP pins for easier hookup (I'm not the only one to ever mix those pins up, am I? )
Every one has their own design choices, but given the choice I also never like to have exposed pads directly against the ground ring because the solder always goes there, and often can pull the component in that direction as well.
When designing a circuit, it is always important not to think not only about the circuit functionality, but about ease of assembly and installation. Often, due to space constraints, we have to sacrifice a little bit to make things fit, but it is always important to keep the end goal in mind (actually building the driver and being able to use it in a flashlight).
Well, I spent hours trying to get my programming clip on one of those MCUs and it didn't work, so I called up Dale and he told me to put the clip in some liquid nitrogen to try and shrink it down a bit. Next, I e-mailed Steve who machined me a beautiful polished aluminum adapter to try and program the chip, but that effort also proved to be futile. Just joking.
This is for the smaller leadless package of the attiny25/45/85 MCUs. You can't program them with a clip, and commercially available programming devices are fairly expensive, so this is an easy alternative. You could also put breakout pads/pins on the driver and solder wires to them to program on a driver, but I find it easier to program them beforehand and save the space--since saving space is the only reason I would ever use one of these MCUs.
Thanks both of you for the advices, and welcome back to the forum wight.
@wight
I didn’t know vias may cause problems, i have seen them on pads sometimes and i had assumed that it was ok.
Better to learn it the easy way :bigsmile:
Right, i have overlooked zener mod, i will see what can be done.
@RMM
Can a component be pulled throught those tiny corners? :~
Anyway that can be solved easily, exposed ground ring is 0.75mm width, so i can shrink it to 0.5mm.
Sure, installation and ease of assenbly will be tested in nexts steps.
Thanks RMM. I asume they only have four legs? I have components on order to program the Attiny MCU's hopefully with the help of a very patient member her, I hope. Lets hope its not to late to teach an old Moose new tricks.