A question on PCB manufacturing
in [Design]
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From: Cydrome Leader on 8 Jun 2010 21:34 Robert Baer <robertbaer(a)localnet.com> wrote: > Bill Sloman wrote: >> On Jun 7, 5:17 pm, Javad Benhangi <benhan...(a)gmail.com> wrote: >>> Thank you everybody. >>> I have a question on PCB manufacturing. I have designed an eight layer >>> board (Top Signal | Power Plane | Gnd | Mid1 Signal | Gnd | Mid 2 >>> signal | Gnd | Bottom Signal). >>> I have some problems with the PCB board. There are five BGA chips on >>> it that according to their montage profile the temperature should >>> reach up to 260 degrees centigrade but the board color and its shape >>> changes as the temperature reaches 220. When I send the problem to the >>> PCB manufacture they said that ere made as regular FR4 material and >>> tin-lead finish and it shouldn?t use in using RoHS temperature >>> profile. I think they should let me know about possible board montage >>> problem and ask me about this option before start manufacturing it >>> because I said them that this is the first experience of mine. >>> Anyway, I?m going to reorder the board but I really don?t know what >>> possible options for the board manufacturing are. What I know is just >>> that A) the board should stand temperature over 260. B) The board >>> should stand multiple montages and de-montage process As the frequency >>> if high, what kind of FR4 board is the best? What is the PCB board >>> electrical test report like? They said to me that they have >>> electrically tested the board but the board had some manufacturing >>> fault? >> >> FR4 is a specification for epoxy-bonded glass-fibre board materials. >> If you want a board that can survive higher temperatures, polyimide >> bonded glass fibre can do better. >> >> You need to search on printed circuit baord materials. The Wikipedia >> entry isn't all that helpful >> >> http://en.wikipedia.org/wiki/Printed_circuit_board >> >> and the manufactureres web sites aren't always all that intelligible >> >> http://www2.dupont.com/Packaging_and_Circuits/en_US/products_services/pcb/index.html#laminate >> >> http://www.viasystems.com/technology/pcb-materials.html >> >> -- >> Bill Sloman, Nijmegen > > Err..polyimide sops up moisture. polyamide aka nylon does absorb moisture. It's unlikey there are nylon PCBs. polyimide aka Kapton and is the plastic that doesn't melt, and is used in flex boards. it's browish.
From: Mycelium on 9 Jun 2010 07:00 On Tue, 08 Jun 2010 00:05:05 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >Bill Sloman wrote: >> On Jun 7, 5:17 pm, Javad Benhangi <benhan...(a)gmail.com> wrote: >>> Thank you everybody. >>> I have a question on PCB manufacturing. I have designed an eight layer >>> board (Top Signal | Power Plane | Gnd | Mid1 Signal | Gnd | Mid 2 >>> signal | Gnd | Bottom Signal). >>> I have some problems with the PCB board. There are five BGA chips on >>> it that according to their montage profile the temperature should >>> reach up to 260 degrees centigrade but the board color and its shape >>> changes as the temperature reaches 220. When I send the problem to the >>> PCB manufacture they said that ere made as regular FR4 material and >>> tin-lead finish and it shouldn�t use in using RoHS temperature >>> profile. I think they should let me know about possible board montage >>> problem and ask me about this option before start manufacturing it >>> because I said them that this is the first experience of mine. >>> Anyway, I�m going to reorder the board but I really don�t know what >>> possible options for the board manufacturing are. What I know is just >>> that A) the board should stand temperature over 260. B) The board >>> should stand multiple montages and de-montage process As the frequency >>> if high, what kind of FR4 board is the best? What is the PCB board >>> electrical test report like? They said to me that they have >>> electrically tested the board but the board had some manufacturing >>> fault? >> >> FR4 is a specification for epoxy-bonded glass-fibre board materials. >> If you want a board that can survive higher temperatures, polyimide >> bonded glass fibre can do better. >> >> You need to search on printed circuit baord materials. The Wikipedia >> entry isn't all that helpful >> >> http://en.wikipedia.org/wiki/Printed_circuit_board >> >> and the manufactureres web sites aren't always all that intelligible >> >> http://www2.dupont.com/Packaging_and_Circuits/en_US/products_services/pcb/index.html#laminate >> >> http://www.viasystems.com/technology/pcb-materials.html >> >> -- >> Bill Sloman, Nijmegen > > Err..polyimide sops up moisture. > Better yet, use Megtron 6; R-5775K and R-5670K, from Matrix USA. > I use that material for units that i GUARANTEE reliable operation to >200C. http://www.matrixusa.us/pdfs/products/Data_Sheet_Megtron_6.pdf
From: Mycelium on 9 Jun 2010 07:02 On Wed, 9 Jun 2010 01:34:33 +0000 (UTC), Cydrome Leader <presence(a)MUNGEpanix.com> wrote: >Robert Baer <robertbaer(a)localnet.com> wrote: >> >> Err..polyimide sops up moisture. > >polyamide aka nylon does absorb moisture. It's unlikey there are nylon >PCBs. > >polyimide aka Kapton and is the plastic that doesn't melt, and is used in >flex boards. it's browish. Well then, force yourself to lower your brow.
From: krw on 9 Jun 2010 23:13 On Wed, 9 Jun 2010 03:16:54 -0700 (PDT), Bill Sloman <bill.sloman(a)ieee.org> wrote: >On Jun 9, 1:05�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >wrote: >> On Tue, 8 Jun 2010 15:58:58 -0700 (PDT),Bill Sloman<bill.slo...(a)ieee.org> >> wrote: >> >> >> >> >On Jun 9, 12:21�am, "k...(a)att.bizzzzzzzzzzzz" >> ><k...(a)att.bizzzzzzzzzzzz> wrote: >> >> On Tue, 8 Jun 2010 04:57:22 -0700 (PDT),Bill Sloman<bill.slo...(a)ieee.org> >> >> wrote: >> >> >> >On Jun 8, 12:52 am, "k...(a)att.bizzzzzzzzzzzz" >> >> ><k...(a)att.bizzzzzzzzzzzz> wrote: >> >> >> On Mon, 7 Jun 2010 08:17:43 -0700 (PDT), Javad Benhangi <benhan...(a)gmail.com> >> >> >> wrote: >> >> >> >> >Thank you everybody. >> >> >> >I have a question on PCB manufacturing. I have designed an eight layer >> >> >> >board (Top Signal | Power Plane | Gnd | Mid1 Signal | Gnd | Mid 2 >> >> >> >signal | Gnd | Bottom Signal). >> >> >> >> Why so many grounds? You're wasting money. >> >> >> >Or avoiding cross-talk and reflections. With fast signals you really >> >> >do need buried ground planes between buried signal layers. >> >> >> Idiot. >> >> >Really? So what's your alternative approach? The stuff you post >> >doesn't suggest that you've ever actually worked with signals fast >> >enough to rub your nose in transmission line problems, and you are >> >obviously too stupid to realise signals with rise times around a >> >nanosecond or faster need this kind of attention. >> >> No, Slowman, you're just too much of an idiot to understand what you spew. >> There is no odds in a power plane next to a ground plane *AT ALL*. �There is >> no reason, in fact it's dangerous, to have more than one ground plane and for >> only eight (nine???) planes, three is absurd. �Two orthogonal signal planes >> per power plane (any power) is fine for just about any PCB usage. > >Not if you are worried about cross-talk. Making the busses orthogonal >does help, but not with a worst case transition - the full width of >the bus changing state at once. Leaving out the ground plane between >the orthogonal busses also makes the individual stripline transmission >lines asymmetric and thus dispersive - not as asymmetrical or as >dispersive as microstrip transmission lines on the outsides of the >board, but not as good as symmetric stripline. Once again you demonstrate why you're unemployable.
From: Bill Sloman on 10 Jun 2010 05:43 On Jun 10, 5:13 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> wrote: > On Wed, 9 Jun 2010 03:16:54 -0700 (PDT),Bill Sloman<bill.slo...(a)ieee.org> > wrote: > > > > >On Jun 9, 1:05 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >wrote: > >> On Tue, 8 Jun 2010 15:58:58 -0700 (PDT),Bill Sloman<bill.slo...(a)ieee.org> > >> wrote: > > >> >On Jun 9, 12:21 am, "k...(a)att.bizzzzzzzzzzzz" > >> ><k...(a)att.bizzzzzzzzzzzz> wrote: > >> >> On Tue, 8 Jun 2010 04:57:22 -0700 (PDT),Bill Sloman<bill.slo...(a)ieee.org> > >> >> wrote: > > >> >> >On Jun 8, 12:52 am, "k...(a)att.bizzzzzzzzzzzz" > >> >> ><k...(a)att.bizzzzzzzzzzzz> wrote: > >> >> >> On Mon, 7 Jun 2010 08:17:43 -0700 (PDT), Javad Benhangi <benhan....(a)gmail.com> > >> >> >> wrote: > > >> >> >> >Thank you everybody. > >> >> >> >I have a question on PCB manufacturing. I have designed an eight layer > >> >> >> >board (Top Signal | Power Plane | Gnd | Mid1 Signal | Gnd | Mid 2 > >> >> >> >signal | Gnd | Bottom Signal). > > >> >> >> Why so many grounds? You're wasting money. > > >> >> >Or avoiding cross-talk and reflections. With fast signals you really > >> >> >do need buried ground planes between buried signal layers. > > >> >> Idiot. > > >> >Really? So what's your alternative approach? The stuff you post > >> >doesn't suggest that you've ever actually worked with signals fast > >> >enough to rub your nose in transmission line problems, and you are > >> >obviously too stupid to realise signals with rise times around a > >> >nanosecond or faster need this kind of attention. > > >> No, Slowman, you're just too much of an idiot to understand what you spew. > >> There is no odds in a power plane next to a ground plane *AT ALL*. There is > >> no reason, in fact it's dangerous, to have more than one ground plane and for > >> only eight (nine???) planes, three is absurd. Two orthogonal signal planes > >> per power plane (any power) is fine for just about any PCB usage. > > >Not if you are worried about cross-talk. Making the busses orthogonal > >does help, but not with a worst case transition - the full width of > >the bus changing state at once. Leaving out the ground plane between > >the orthogonal busses also makes the individual stripline transmission > >lines asymmetric and thus dispersive - not as asymmetrical or as > >dispersive as microstrip transmission lines on the outsides of the > >board, but not as good as symmetric stripline. > > Once again you demonstrate why you're unemployable. Once again you demonstrate that you are the idiot. Your claim that the board had too many grounds planes was posted when we didn't know that the board was carrying "600-700Mbps signals" which Javad Benhangi didn't tell us until the 9th June. My reaction to your post was based on my own experience with slightly faster signals - Gigabit Logic's GaAs parts, in a system built around an 800MHz sysnchronous clock - where the extra buried ground/power planes had seemed like a very good idea. You've seen - presumably slower - boards that worked with fewer ground/ power planes than Javad Benhangi used, as have we all You don't tell us the edge speeds or the logic swing, of the fastest examples of the boards that you know worked, and you seem singularly incapable of understanding that board stack-ups that worked for TTL coud be marginal - or worse - with modern ECL/LVDS/CML singal levels and speeds. http://www.national.com/nationaledge/may03/article.html That level of complacent ignorance should render you unemployable, but there are pockets of complacent ignorance in every industry. They are characteristically inhabited by people like you, who confidently assume that anybody who disagrees with them has to be an idiot, and don't bother thinking about the reasons adduced for the disagreement, and don't see any necessity to produce a rational, evidence-based justification for their counter-opinion. -- Bill Sloman, Nijmegen
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