What are 6.5 Digit Multimeters Good For?
in [Design]
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From: krw on 16 Mar 2010 19:28 On Tue, 16 Mar 2010 04:24:59 -0700, Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote: >On Mon, 15 Mar 2010 22:26:58 -0500, "krw(a)att.bizzzzzzzzzzzz" ><krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Mon, 15 Mar 2010 20:17:05 -0700, Archimedes' Lever >><OneBigLever(a)InfiniteSeries.Org> wrote: >> >>>On Mon, 15 Mar 2010 19:53:04 -0700, John Larkin >>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Mon, 15 Mar 2010 19:47:01 -0700, Archimedes' Lever >>>><OneBigLever(a)InfiniteSeries.Org> wrote: >>>> >>>>>On Mon, 15 Mar 2010 12:11:23 -0700, John Larkin >>>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>> >>>>>>On Fri, 12 Mar 2010 18:56:02 -0800, Archimedes' Lever >>>>>><OneBigLever(a)InfiniteSeries.Org> wrote: >>>>>> >>>>>>>On Fri, 12 Mar 2010 15:23:12 -0800, John Larkin >>>>>>><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>> >>>>>>>> >>>>>>>>Except that you never get too much copper... always too little. >>>>>>>> >>>>>>>>John >>>>>>> >>>>>>> >>>>>>> Maybe from your board house, dipshit. >>>>>> >>>>>>Measure the sheet resistivity of traces on a few of your boards and >>>>>>tell us what you see. >>>>>> >>>>>>John >>>>> >>>>> >>>>> You do know that we do not use copper boards any more, right? >>>> >>>>I didn't know that. What do you use? >>>> >>>>John >>> >>> It is an RoHS world, John. What do you think we use? >> >>What does RoHS have to do with Copper, AlwaysWrong? > > The field is called "intermetallics". I wouldn't expect a ditz like >you to get it, always-fucked-in-the-head. IOW, you don't know. We _all_ knew that, AlwaysWrong. >>> It ain't HASL over Copper or SMOBC, I'll tell ya. >> >>IOW, you don't know. > > You wouldn't know what I know. You never will. And for that I am thankful! >You are pathetic, Williams. You're always wrong, but *everyone* knows that, AlwaysWrong.
From: Archimedes' Lever on 16 Mar 2010 20:21 On Tue, 16 Mar 2010 06:58:50 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Tue, 16 Mar 2010 00:06:53 -0500, "Randomly" ><fburfell2000(a)n_o_s_p_a_m.n_o_s_p_a_m.yahoo.com> wrote: > >>>It's interesting to calculate the resistance of traces and actually >>>measure them. Most pcb houses skimp on plating, so when you specify "1 >>>oz" copper, you seldom get it. >> >>The only place copper is plated is in the holes. The 1 oz copper layer for >>traces is a copper sheet that is laminated to the board. It's rolled out to >>the proper 1.4 mil thickness when it's manufactured. It's not plated on by >>the PCB manufacturer. >> >>You may be making measurement errors when you measure the traces, 1 amp can >>be a lot of current on small traces and you may be heating that trace up >>quite a bit. Copper has a substantial thermal coefficient of resistance, >>heat it up by 25C and the resistance goes up 10%. Try dropping your current >>to 0.1A and see how your measurements change. > >I think my measurements are accurate, and I often include a test trace >whose geometry is suitable for accurate sheet resistance measurement. > >If I include a fab note demanding a minimum sheet resistance, or say >"START WITH 1 OZ COPPER" I usually get below 600 uohms/square. If I >just say "COPPERCLAD 1 OZ" I usually don't. > >John > > The sheets are 4' x 8' and the cladding is industry standard, you dopey ditz! I know because my dad made some of the very first machines that were used by the industry to make the current form factor boardstock. That would be Cincinnati Milacron, Inc., which at the time would have been named The Cincinnati Milling Machine Company. There are not very many products you could name that didn't use Cincinnati machines. Fuller brush company... Your hair brush injection molders. Ebonite... Your bowling balls, GE jet engines, FMC corp M1-A1 MBTs. All three US auto makers. The list goes on for hundreds of brands, products, industries. Now, most companies have bought Japanese machining centers. Milacron probably not doing so well... lemmie check real quick... DAMN! They have been bought out by a conglomerate with private stock! MAG Industrial Automation owns Milacron now! Oh well, they were the guys. If you are getting it thinner, then your PCB house... isn't one. They should know how to correctly clean a PCB without losing copper. Also, your measurement accuracy can be off due to you not performing the test completely correctly. Kind of like the vapor phase thing. It works for you, so you do not care if you are actually doing it right or not. Sorry, but in this case, if you do not know where the error(s) get(s) introduced, you will knot know what your resultant figures mean, nor how to offset them properly to correct for the errors that get introduced in to the not quite ideal test scenario. Not ideal? What is the bad element? YOU, Johnny boy. All it would take is a single mistake, and the difference you refer to (600 as compared to 1000) is very likely completely due to said error. I'd say that even though you think you are, you have failed to compensate for the lead resistance of your test. What you should do is apply a current and measure the voltage between the NUT (NodeSpan Under Test). Far better than you thinking that you can measure micro-ohms accurately, much less properly.
From: John Larkin on 16 Mar 2010 20:52 On Tue, 16 Mar 2010 17:21:58 -0700, Archimedes' Lever <OneBigLever(a)InfiniteSeries.Org> wrote: >On Tue, 16 Mar 2010 06:58:50 -0700, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Tue, 16 Mar 2010 00:06:53 -0500, "Randomly" >><fburfell2000(a)n_o_s_p_a_m.n_o_s_p_a_m.yahoo.com> wrote: >> >>>>It's interesting to calculate the resistance of traces and actually >>>>measure them. Most pcb houses skimp on plating, so when you specify "1 >>>>oz" copper, you seldom get it. >>> >>>The only place copper is plated is in the holes. The 1 oz copper layer for >>>traces is a copper sheet that is laminated to the board. It's rolled out to >>>the proper 1.4 mil thickness when it's manufactured. It's not plated on by >>>the PCB manufacturer. >>> >>>You may be making measurement errors when you measure the traces, 1 amp can >>>be a lot of current on small traces and you may be heating that trace up >>>quite a bit. Copper has a substantial thermal coefficient of resistance, >>>heat it up by 25C and the resistance goes up 10%. Try dropping your current >>>to 0.1A and see how your measurements change. >> >>I think my measurements are accurate, and I often include a test trace >>whose geometry is suitable for accurate sheet resistance measurement. >> >>If I include a fab note demanding a minimum sheet resistance, or say >>"START WITH 1 OZ COPPER" I usually get below 600 uohms/square. If I >>just say "COPPERCLAD 1 OZ" I usually don't. >> >>John >> >> > The sheets are 4' x 8' and the cladding is industry standard, you dopey >ditz! I know because my dad made some of the very first machines that >were used by the industry to make the current form factor boardstock. >That would be Cincinnati Milacron, Inc., which at the time would have >been named The Cincinnati Milling Machine Company. There are not very >many products you could name that didn't use Cincinnati machines. Fuller >brush company... Your hair brush injection molders. Ebonite... Your >bowling balls, GE jet engines, FMC corp M1-A1 MBTs. All three US auto >makers. The list goes on for hundreds of brands, products, industries. >Now, most companies have bought Japanese machining centers. Milacron >probably not doing so well... lemmie check real quick... DAMN! They >have been bought out by a conglomerate with private stock! MAG >Industrial Automation owns Milacron now! Oh well, they were the guys. > > If you are getting it thinner, then your PCB house... isn't one. They >should know how to correctly clean a PCB without losing copper. Also, >your measurement accuracy can be off due to you not performing the test >completely correctly. > > Kind of like the vapor phase thing. It works for you, so you do not >care if you are actually doing it right or not. > > Sorry, but in this case, if you do not know where the error(s) get(s) >introduced, you will knot know what your resultant figures mean, nor how >to offset them properly to correct for the errors that get introduced in >to the not quite ideal test scenario. > > Not ideal? What is the bad element? YOU, Johnny boy. > > All it would take is a single mistake, and the difference you refer to >(600 as compared to 1000) is very likely completely due to said error. > > I'd say that even though you think you are, you have failed to >compensate for the lead resistance of your test. What you should do is >apply a current and measure the voltage between the NUT (NodeSpan Under >Test). Far better than you thinking that you can measure micro-ohms >accurately, much less properly. If you don't use copper traces on your pc boards, what do you use? John
From: Don Lancaster on 17 Mar 2010 00:09 Jan Panteltje wrote: > On a sunny day (Fri, 12 Mar 2010 15:03:42 -0600) it happened John Fields > <jfields(a)austininstruments.com> wrote in > <8talp59g6d4lma3q6p93ttnnsn4cnm6m71(a)4ax.com>: > >> On Fri, 12 Mar 2010 20:15:16 GMT, Jan Panteltje >> <pNaonStpealmtje(a)yahoo.com> wrote: >> >>> On a sunny day (Fri, 12 Mar 2010 09:33:25 -0800) it happened D from BC >>> <myrealaddress(a)comic.com> wrote in <MPG.26041ac522f727379896f0(a)209.197.12.12>: >>> >>>> In article <hndc5b$37k$1(a)news.albasani.net>, pNaonStpealmtje(a)yahoo.com >>>> says... >>>>> On a sunny day (Thu, 11 Mar 2010 17:56:35 -0800) it happened D from BC >>>>> <myrealaddress(a)comic.com> wrote in <MPG.26033f321480b139896e5(a)209.197.12.12>: >>>>> >>>>>> 6.5 digit multimeters sell around $1000.00. >>>>>> For electronics development, are these $1000 multimeters really >>>>>> necessary? >>>>>> What are they good for? >>>>> They are not needed, all you need is a 5 Euro multimeter, >>>>> and in extreme cases a precise reference. >>>>> That means if you use one of those reference chips, you borrow >>>>> the very accurate multimeter for a day, measure your reference chip, >>>>> write it down, and use that to calibrate your cheap multimeter, >>>>> or o compute it's real value, >>>>> Saved: 1000$ >>>>> >>>>> Of course there are exceptions, >>>>> but in places where that counts they usually have a lot of ++++expensive stuff anyways. >>>>> Usually places where nothing really useful is done, like in CERN, or ITER, or LIGO, >>>>> etc. >>>> How about mohm measurements? Maybe that's handy. >>>> My DMM only goes to 0.1 ohm. >>>> I thought of measuring DCR of coils or pcb trace resistance for sim >>>> accuracy. >>> I have a controlled current souce. >>> Stuff 1 A through the .1 resistor and measure the voltage drop? >> --- >> And you've determined the accuracy of the current source and the >> resistor, how??? >> >> JF > > The question was not about accuracy, but how to measure .1 Ohm. The neatest use of a 6.5 or higher DVM is for temperature measurement. It easily spots a hand at a distance of three feet. -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don(a)tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com
From: Don Lancaster on 17 Mar 2010 00:15
Archimedes' Lever wrote: > On Tue, 16 Mar 2010 06:58:50 -0700, John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Tue, 16 Mar 2010 00:06:53 -0500, "Randomly" >> <fburfell2000(a)n_o_s_p_a_m.n_o_s_p_a_m.yahoo.com> wrote: >> >>>> It's interesting to calculate the resistance of traces and actually >>>> measure them. Most pcb houses skimp on plating, so when you specify "1 >>>> oz" copper, you seldom get it. >>> The only place copper is plated is in the holes. The 1 oz copper layer for >>> traces is a copper sheet that is laminated to the board. It's rolled out to >>> the proper 1.4 mil thickness when it's manufactured. It's not plated on by >>> the PCB manufacturer. >>> >>> You may be making measurement errors when you measure the traces, 1 amp can >>> be a lot of current on small traces and you may be heating that trace up >>> quite a bit. Copper has a substantial thermal coefficient of resistance, >>> heat it up by 25C and the resistance goes up 10%. Try dropping your current >>> to 0.1A and see how your measurements change. >> I think my measurements are accurate, and I often include a test trace >> whose geometry is suitable for accurate sheet resistance measurement. >> >> If I include a fab note demanding a minimum sheet resistance, or say >> "START WITH 1 OZ COPPER" I usually get below 600 uohms/square. If I >> just say "COPPERCLAD 1 OZ" I usually don't. >> >> John >> >> > The sheets are 4' x 8' and the cladding is industry standard http://www.tinaja.com/whtnu09.asp#d02-19-09 -- Many thanks, Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss: http://www.tinaja.com/whtnu.xml email: don(a)tinaja.com Please visit my GURU's LAIR web site at http://www.tinaja.com |