Post by thread:[EE]: 0805 underpass, handsoldering

This post reminded me of rumors that 1206 packaged components are being phased out, anyone on the list know why or when? I find the 1206 allows compact layouts with fairly easy hand soldering, I'll miss them if they do disappear. Nigel On Friday, February 15, 2002 11:00 AM, Stuart Meier [SMTP:spam_OUTstuartmeierTakeThisOuTRYG1.FREESERVE.CO.UK] wrote: {Quote hidden}> Looks like I am going to be forced by the demise of 1206 caps to put > underpasses under 0805s, which I have always avoided. > > Anyone doing this with handsoldering? What width trace width/clearance > to 0805 pads works for you? > > Stuart > > -- > http://www.piclist.com hint: To leave the PICList > .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

Hi Everyone, Just to add my $0.02.. I recently went to talk with an assembly contractor and they "suggested" that I stick with 0805s or 0603s as the 1206s where being phased out by the manufactures as the 0805 is much more popular. This doesn't mean that you can't or won't be able to get 1206s, just that they will become rarer and take longer to source and also be more expensive. If you want your product to be easily manufacturable in a few years, go with the 0805s.. I've run a trace between the 0805 pads before and didn't have a problem using the 8mil/8mil rules.. It was a "last resort" type of thing though, but I did have a solder mask and that really helps. Virtually no chance of messing it up then :) Cheers, Ash. --- Ashley Roll Digital Nemesis Pty Ltd http://www.digitalnemesis.com Mobile: +61 (0)417 705 718 > {Original Message removed}

At 09:31 AM 2/16/02 +1000, you wrote: >Hi Everyone, > >Just to add my $0.02.. I recently went to talk with an assembly contractor >and they "suggested" that I stick with 0805s or 0603s as the 1206s where >being phased out by the manufactures as the 0805 is much more popular. The prices on 0603 resistors are less than 0805s- in quantity (100K+) 0402 here we come... and those pesky 0201s are probably not far behind, at least for resistors. Capacitors won't shrink as fast, for obvious reasons. Best regards Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

Hi Spehro, Yep, unfortunately I still have to hand assemble some stuff.. 0603s are about my limit there I think :) Sometimes I think its a shame that the 1206 or 0805 size resistor arrays are so expensive (compared to the individual ones).. 4 or 8 resistors in one go! I wonder how long it will be until its easier and faster to just print the resistors directly on the PCB during manufacture or assembly.. Does anyone know if this is being seriously developed? I know there are a bunch of 3D printing efforts.. Cheers, Ash. --- Ashley Roll Digital Nemesis Pty Ltd http://www.digitalnemesis.com Mobile: +61 (0)417 705 718 > {Original Message removed}

At 10:18 AM 2/16/02 +1000, you wrote: >Hi Spehro, Hi! >Yep, unfortunately I still have to hand assemble some stuff.. 0603s are >about my limit there I think :) Sometimes I think its a shame that the 1206 >or 0805 size resistor arrays are so expensive (compared to the individual >ones).. 4 or 8 resistors in one go! I calculate the break-even at two resistors for the 4-resistor 8-pin arrays! I use LOTS of them, even for analog stuff. The price is good in quantity, and the area/mounting cost is low. Plenty of sources. They can be hand- soldered easily enough with a bit of practice. Yes, I agree that 0603 is about as low as I want to go by hand. Unfortunately, the PCB designs are committed to the size, so you can't properly just use whatever's available at the moment without re-laying out the board. 8-( Not a problem if you're making cell phones with a 6-month design life, but for the rest of us.. >I wonder how long it will be until its easier and faster to just print the >resistors directly on the PCB during manufacture or assembly.. Does anyone >know if this is being seriously developed? I know there are a bunch of 3D >printing efforts.. It's difficult- they used to make hybrids by screen-printing resistors and firing on alumina. All the variables- it was hard to get 30% tolerance without trimming. The cheap little 5% and 1% resistors are not bad for almost free! But for consumer stuff, I think there are organic (low temperature) compounds that you can print on and "fire" at reasonable temperatures- like the carbon stuff that they use to replace gold-plating for silicone key contacts, and for printed jumpers on low-end PCBs. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffspam_OUTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com 9/11 United we Stand -- http://www.piclist.com hint: To leave the PICList @spam@piclist-unsubscribe-requestKILLspammitvma.mit.edu

Another *very* important point to remember concerning chip resistors is power handling ability. I do a lot of industrial designs where the resistor carries some current and dissipates some power, often continuously under overload or error conditions. They are also mostly high-reliability designs. Factor in elevated ambient temperatures and things get a bit more complicated as the power dissipation of the chip is reduced. Remember that a 1206 chip is basically a 1/8W->1/10W resistor. I don't like to run more than about 60% maximum power on any resistor to reduce the maximum chip temperature and maximize long term reliability. Once you get to 0805, 0603 and 0402 chips, you begin to have to worry about even LOGIC signals possibly damaging a resistor in an overload state -- for instance a 220 Ohm, 0402 in series with a PIC output to say a Mosfet gate. If the gate gets shorted to ground and the PIC output is high (near 5V), the power in the resistor becomes ~110mW and that will cook an 0402 resistor (or even an 0603 and will be borderline on an 0805, depending on ambient temperature). This is also something to remember when sizing resistors for input overload clamping circuits. It's easy to forget when designing with SMD chip resistors [not that I've ever made that mistake ;-)] I can see where the smaller parts will continue to be cheaper and preferred over time, but I also see a need for the larger chips for a long time also. I don't think they'll go away any time soon, but I have started using 0805's wherever possible. Matt Pobursky Maximum Performance Systems On Fri, 15 Feb 2002 19:21:14 -0500, Spehro Pefhany wrote: {Quote hidden}>At 09:31 AM 2/16/02 +1000, you wrote: >>Hi Everyone, >> >>Just to add my $0.02.. I recently went to talk with an assembly >>contractor and they "suggested" that I stick with 0805s or >>0603s as the 1206s where being phased out by the manufactures >>as the 0805 is much more popular. > >The prices on 0603 resistors are less than 0805s- in quantity >(100K+) > >0402 here we come... and those pesky 0201s are probably not far >behind, at least for resistors. Capacitors won't shrink as fast, >for obvious reasons. > -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

>I wonder how long it will be until its easier and faster to just print >the resistors directly on the PCB during manufacture or assembly.. Does >anyone know if this is being seriously developed? I know there are a >bunch of 3D printing efforts.. Printed resistors have been a standard for hybrid circuits for a very long time. Several kinds of high volume consumer products use this all the time (like pocket calculators and IR remote controls). If you have a high enough volume and space constraints and strange resistor values then it may be good for you. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads