Honored ContributorI am almost done with my PCB design, the "soldermask" pretty much doubles the price for the 2 prototype boards. How criticial is that for a first project? Can I solder it all together without the mask and novice soldering skills, whats you advice? I am using PCB123
Honored ContributorWhat's the FPGA package? PQFP? Hand-soldering is generally possible without solder mask, but you should have solder wick at hand to remove possible shorts.
Good luckHonored ContributorThat depends on the nature of the solder land patterens that you need to solder to.
The solder mask is used to control how far solder will reflow up the trace lengths. If you are real good with a fine pointed soldering tool you should be OK. (If you are really that concerned with costs, then make sure you stay in school so that some day you will make lots more money and not worry about those sort of things.:) ) Let us know how it turns out.Honored ContributorThanks for Info, I am going to use the 144pin Cyclone II PQFP. Ive got some solder wick ready for shorts. Thanks for advice. And I am thinking the C0805 Capactitors for my power circuit may be a littel tricky to solder. After I build this toy/game thing and put it on ebay, Ill order more boards with the soldermask and build more.
Thanks for your help with my evil plans. eviltwinzzzHonored ContributorThe only answer if flux. Use a lot of it on the pads on the pcb, put the component on it. Till now it is easy to align the chip, because the flux will hold it in place more or less. Solder some corners first (don't worry about shorts now).
Now put a very small quantity of solder on the iron, and slide gently on each row of pins. Because of the huge amount of flux, no shorts should be present except maybe on the corner position you stop (remove this with the wick). For the small capacitors and resistors, put a but of flux on a piece of paper, and dip the capacitor in the flux with a pincet, place it on the board and solder one side. solder the other side with a bit of fresh tin on the iron (you have two hands available now, because the component should be fixed on one side already). Touch the side soldered first again with some fresh tin-lead. The last step is crusial, because a solder joint placed with a pincet in the other hand is always worse than a joint made by the tip touching the tin-lead directly on the component. If you start shaking with your hand, stop and get a walk. Don't hurry. I hope it works... StefaanHonored ContributorExcellent information, thanks a lot
I found what svbh was talking about one youtube http://youtube.com/watch?v=3nn7ugwymby&feature=related if anyone feels linking to another youtube like this is innapropriate, I will take this post downHonored ContributorI am now desingin the traces from my power circuits and ground to the FPGA, then the circuits from the programming chip. Any good pointers on how to do this neatly, mistakes that might come up?
Honored Contributor1) Use a ground plane
2) I would route any critical/high speed signals first. 3) Those free (PCB123, ExpressPCB,etc.) software packages are free for a reason(no error checking). No matter how hard I've tried with those, I always end up with mistakes (some worse than others).Honored ContributorSince I am driving lights, sensors and relays, I maye not need anything faster then 10mhz, for the programming circuit, thats my plan for making it as tolerant to my mistakes as possible. Not sure is I can do a ground plane for a 2 layer board though. The only way would be to make copper pours around my other circuits on the bottom.
Honored ContributorTo my opinion, the minimum requirement is a meshed ground net with low inductance bypass capacitors at each supply pin. Although no high-speed I/O is involved, signal quality of input clock and configuration/programming circuit may be an issue as well. If PLL usage is intended, it's supply bypassing is another, even more critical point.
