If having to switch between nozzles is a significant issue then there is room for a new pick and place equipment company that builds a multi-nozzle tool. In reality, I doubt that it has much of an effect on cost.
I wonder how the throughput of the pick and place tool compares to the throughput of the reflow oven? or wash or final inspection? Steve Meier On Fri, 2008-10-31 at 20:31 -0400, Bob Paddock wrote: > On Friday 31 October 2008 03:43:20 pm Joerg wrote: > > > Much better. If you want to be extra good provide another 0.1uF parallel > > to the AVDD caps, close to pin 3. C13 in your channel.sch file. However, > > 10uF cermamics in SMT are already quite good these days, and cheap. If > > you can get C13 closer to pin 3 that would also help. > > "A bypass-capacitor dialogue peels back the layers, Part 1" > http://www.planetanalog.com/article/printableArticle.jhtml?articleID=207602816&printable=true > > Interesting article that says it is better to use bypass caps in different > size packages due to ESL effects. > > Part 2: > http://www.planetanalog.com/article/printableArticle.jhtml?articleID=208402807&printable=true > > ... > "David: Follow the currents. There is always a loop for current, there are > always fringe currents inside the ground plane, and voltage drops associated > with those currents. The cuts prevent the currents from mingling so they > could no longer couple directly from Input A to Input B (or the reverse). > > Tamara: So this was an example of a ground plane gone wrong. The ground plane > with cuts in it actually performed better. > > David: Yeah, most people believe that providing a low-impedance connection to > ground (like a plane) is enough. Sometimes that is true, but it's too one > sided. If you need really high isolation, you need to follow and control the > currents around the entire loop. " > ... > > Part 3: > http://www.planetanalog.com/article/printableArticle.jhtml?articleID=209600453&printable=true > > Do a search for "Bypass" on Planet Analog for related articles. > > Doesn't look like they used PCB in the screen shots. ;-) > > > Might want to rotate C11 and squeeze it in between R18/C12 so it's > > closer to pin 4. > > When "Squeezing" parts between things, consider what happens at the assembly > stage. For example you put a tiny 0402 0.1 cap between to comparatively > large parts like a 1206 resistor and a large tantalum capacitor. > > This could create a problem with the Pick&Place machine where your board > might need two passes on the machine, increasing your assembly charges. > > The 0402 cap will need a tiny nozzle to place it and fit between the larger > parts, while the larger parts need larger nozzle due to the part mass. > If the 0402 part is on the outside of the larger parts then it is possible > that the larger nozzle could be used for all operations in that area, > this saves time hence cost. > > _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
