Seeed has a "panelized PCBs" option with values of 1 to 5, but I never understood what that meant exactly. Am I supposed to make X copies of my design in the Gerber file that I send? Or if I choose that option, will they duplicate my design for me? Do they separate the panelized PCBs before shipping them? Sorry for the dumb questions, but I've never been clear exact what panelization is all about, or how to do it.
That option on their website had me slightly confused during my last order too. I think that option for Seeed is if you want to buy large boards that contain up to 5 different designs that are all panelized onto a single board:
I'm fairly sure that if your quantities are large enough, panelization is cheaper than buying the individual boards (or at least it was). You can do different designs, but a lot of the time, when people panelize they are really just putting multiple copies of their same board onto the same gerber. I've never done it but the place I work for has done it in the past. Depending on how you do it, you can just break the boards apart in your hand when you receive them and they still look nice and clean. I think there are tools within the PCB software to do it for you. IIRC there are programs that can take your gerbers and panelize them for you too.
When I was looking at board assembly places a while back, at least one of them had a minimum board size and said you had to panelize if you wanted to do boards smaller than their minimum size. From the perspective of the assembly process that I've seen where I work (they've been getting a pick and place machine up and running), I can see where it would be easier to do a larger panelized board--your stencil will put paste on 6 boards at a time, and the pick and place will populate all 6 boards before a human has to pull out the finished PCB and put in a new one. I'm certainly not an expert at any of this, but that's just what I've seen...
dougg3, this is amazing work. Youíve actually successfully designed a high-speed PCB, something Iíve been thinking of doing for a few months now but just couldnít get to it. Iím going to be studying your schematics soon just to get an idea. Since llfx have already issued a small warning, I guess you can actually start selling a few of these if you have them you. Might not be a bad idea.
Thanks! I actually don't know if I did it completely right. For speeds high enough, I think you're also supposed to worry about meandering traces so they're all the same length. Whatever I did, it seems to work! I have no plans to sell them, but it sounds like fraveydank has it covered!
Meant to say: I checked out Seeed's panelization option, and it's a bit different from what I'm used to for panelization options for proto houses. I'm used to "give us Gerbers for one project and we'll make a panel with n of them", while Seeed means "these Gerbers have n projects contained on them and must be v-scored accordingly", which is weird.
I don't feel like replicating it myself, so I might see what I can get out of Advanced Circuits in this kind of quantity, because I know they'll do the panelization automatically; either that, or I might see if the medium run service on OSHPark will do custom specs (thanks again for the reminder about board thickness). I know they'll leave it panelized post-slicing if they know it's getting sent off to an assembly house, because when I got some boards back from the assembly house they sent it to, the balance of the boards were still conjoined.
Advanced circuits was really expensive comapred to Seeed, so I just placed the order with Seeed for unpanelized PCBs ($231.78 for 125 boards plus shipping). It'll be some work to assemble them, but with my hot air station it shouldn't be so bad. I lost my toaster oven in a move many years ago and haven't bothered to replace it. It was really a shame, because a $20 toaster oven's "toast" setting had almost a perfect reflow profile and I didn't even need to modify it. Oh well.
Anyway, once I start getting them assembled and tested, I'll probably start putting them up for sale on eBay. I'll make sure people "in the know" can get them at my cost, probably via a pre-arranged "make an offer" price. It'll be nice to have my IIfx motherboard finally working!
Next project for me: logic analyzer (Mictor) adaptors for the IIci cache card slot and 030 PDS slot (I have a IIci that needs debugging and a nice HP logic analyzer sitting idle). I should maybe also make a dedicated test jig to attach to one of my FPGA eval boards so I don't have to keep stressing the IIfx's SIMM slots to test.
It'll be some work to assemble them, but with my hot air station it shouldn't be so bad.
What kind of hot air setup do you have? I've tried to do SMT (re-)work with a Hakko FM-2029 hot air gun, but I switched back to simple drag soldering after I found that getting a sane temperature profile was really difficult and I tended to just roast things to death. My assumption was that I needed a pre-heater, but I was wary of buying one just to find out whether it'd make the difference.
I have just one of the moderately priced ($110 or so) Chinese ones from eBay. It came with a whole assortment of tips, and also has a somewhat OK temperature controlled iron attached as well (which I use as a secondary iron with my Hakko primary). They key with the hot air station is patience... patience, and motion. Don't let the thing sit in one spot the whole time, or you'll toast things. I keep it moving and do a profile test on a penny beforehand.
I also got a Puhui preheater off eBay, primarily for some reballing work on PS3s. It hadn't occurred to me to use it for this, but now that you mention it, it makes a lot of sense. I'll try it out when the boards get here and report back.
No, I didn't. I've had reasonably good luck in the past with just spreading a line of paste on the pads, seating the chips and heating them. As long as the pads are large enough (this works well with down to QFP sizes) and you use leaded solder and plenty of flux, it works pretty well. SOJ leads are somewhat more separated than QFP leads, so I'm not really even anticipating much cleanup.
If I were to send it off for assembly, I'd expect the assembly house to make their own stencil (most of the better ones do because they like to work with their own).
Thanks! trag's design actually only has two layers and it still works, but I feel safer using a four-layer board for it. I made this with a freemium trial license for Eagle, BTW. I've also been replicating the design in KiCad and DipTrace as an experiment to decide what other PCB software is good.
Have you tried Osmond PCB? I remember mentioning it on 68kmla and someone tried it, but I can't remember if that was you.