[time-nuts] time-nuts Digest, Vol 47, Issue 6

Don Collie jnr merdon at xtra.co.nz
Tue Jun 3 04:13:01 EDT 2008


Thankyou Bruce! It is god to know these things.
Cheers,........................................................Don C.
PS : My "O" key is defective - I am not trying to convert you.


----- Original Message ----- 
From: <time-nuts-request at febo.com>
To: <time-nuts at febo.com>
Sent: Tuesday, June 03, 2008 2:58 PM
Subject: time-nuts Digest, Vol 47, Issue 6


> Send time-nuts mailing list submissions to
> time-nuts at febo.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> or, via email, send a message with subject or body 'help' to
> time-nuts-request at febo.com
>
> You can reach the person managing the list at
> time-nuts-owner at febo.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of time-nuts digest..."
>
>
> Today's Topics:
>
>   1. Re: time-nuts Digest, Vol 47, Issue 5 (Don Collie jnr)
>   2. Re: PCB design questions thread II (John Miles)
>   3. Re: time-nuts Digest, Vol 47, Issue 5 (Bruce Griffiths)
>   4. Re: time-nuts Digest, Vol 47, Issue 5 (M. Warner Losh)
>   5. Re: PCB design questions thread II (Prologix)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 3 Jun 2008 14:21:27 +1200
> From: "Don Collie jnr" <merdon at xtra.co.nz>
> Subject: Re: [time-nuts] time-nuts Digest, Vol 47, Issue 5
> To: <time-nuts at febo.com>
> Message-ID: <81FF3D88ABB94896815D4DA829AA1B57 at MAIN>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> I`m curious : What is a "virgin teflon standoff", and does it have 
> anything
> to do with the "teflon Don"?
> I don`t see much SMD, here, at the extreme edge of the known Universe, but 
> I
> can see that the single sided approach would make tracing a circuit  much
> easier,......
> ...........................................................................Don
> C.
>
> PS : Perhaps the "double sided approach" would be more suitable for
> Schitzophernics - a few of whome it has been my pleasure to meet.
>
> ----- Original Message ----- 
> From: <time-nuts-request at febo.com>
> To: <time-nuts at febo.com>
> Sent: Tuesday, June 03, 2008 1:53 PM
> Subject: time-nuts Digest, Vol 47, Issue 5
>
>
>> Send time-nuts mailing list submissions to
>> time-nuts at febo.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> or, via email, send a message with subject or body 'help' to
>> time-nuts-request at febo.com
>>
>> You can reach the person managing the list at
>> time-nuts-owner at febo.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of time-nuts digest..."
>>
>>
>> Today's Topics:
>>
>>   1. Re: PCB design questions thread II (John Day)
>>   2. Re: PCB design questions thread II (Bruce Griffiths)
>>   3. Re: PCB design questions thread II (Matthew Smith)
>>   4. Re: PCB design questions thread II (Bob Paddock)
>>   5. Re: PCB design questions thread II (Matthew Smith)
>>   6. Re: PCB design questions thread II (Bob Paddock)
>>   7. Re: PCB design questions thread II (Chuck Harris)
>>   8. Re: PCB design questions thread II (Bob Paddock)
>>   9. Re: PCB design questions thread II (Keith Payea)
>>  10. Re: PCB design questions (Didier Juges)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Mon, 02 Jun 2008 20:20:14 -0400
>> From: John Day <johnday at wordsnimages.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <mailman.2641.1212458003.2318.time-nuts at febo.com>
>> Content-Type: text/plain; charset="us-ascii"; format=flowed
>>
>> At 08:04 PM 6/2/2008, you wrote:
>>>Personally I *hate* turning boards over and clipping leads.
>>>
>>>And I'd much rather layout SMD than T/H.
>>
>> A man after my own heart. 0.5mm and even 0.4mm pin pitch is fine, QFN
>> is doable, but takes patience sadly BGA is a bit beyond the pale for
>> me right now until I get some more gear. Until I started the job I
>> have now I hadn't done any PTH in nearly 15 years - and now I know
>> why! And now I know why we have technicians to assemble prototypes,
>> but none of them can outdo me for speed and accuracy on an 0.5mm PQFP
>> FPGA.
>>
>> If you are going to do a lot of SMT work by hand, then a good stereo
>> microscope and a Metcal MX500 series iron are almost indispensable.
>>
>> John
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Tue, 03 Jun 2008 12:20:26 +1200
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <48448E4A.1080309 at xtra.co.nz>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> christopher hoover wrote:
>>> John Miles wrote:
>>>
>>>> For one-off PCBs, I've had good luck with www.batchpcb.com .
>>>>
>>>
>>> I agree.  I've used them once and have been happy with the
>>> results, you just can't be in any hurry.  Unfortunately,
>>> there's no indication of how long it will take a priori.
>>>
>>>
>>>> SMD is not hard to work with by hand, down to 0603 or thereabouts
>>>> depending on eyesight and/or equipment.  I find it easier to deal
>>>> with than through-hole, frankly.
>>>>
>>>
>>> I agree with the first part, but I actually find SMD to be easier
>>> than T/H, if you stick with 0603 and larger for the passives.  I
>>> find SMD not only easier but quite bit a faster.
>>>
>>> SMD IC packages are easy once you get the hang of them, but a
>>> microscope is needed for inspecting and fixing fine pitched parts.
>>> (I think this is a bit of surprise to some folks.)
>>>
>>> Personally I *hate* turning boards over and clipping leads.
>>>
>>> And I'd much rather layout SMD than T/H.
>>>
>>> -ch
>>>
>> However for low frequency work the low thermal mass of resistors and
>> opamps in smt packages can be problematic.
>> Also SMT packages are more sensitive to board deflections and vibration.
>>
>> Using guard rings with some SMT parts is difficult to impossible.
>> You no longer have the option of directly connecting a leakage sensitive
>> lead to a virgin teflon standoff.
>>
>> Mixers and phase detectors with dc and low frequency isolated grounds
>> for the IF and RF ports dont appear to be available in SMT packages.
>>
>> How do you cope with SMT parts (eg high frequency ADCs) with metal
>> thermal transfer /ground connections under the package itself?
>>
>> Bruce
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Tue, 03 Jun 2008 10:04:44 +0930
>> From: Matthew Smith <matt at smiffytech.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <484491A4.4020809 at smiffytech.com>
>> Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>> Quoth Bruce Griffiths at 2008-06-03 09:50...
>>
>>> How do you cope with SMT parts (eg high frequency ADCs) with metal
>>> thermal transfer /ground connections under the package itself?
>>
>> Haven't done it myself, but interested to hear others experiences.  I'm
>> guessing that this would be a job for solder paste and a toaster oven -
>> or high-tech equivalent.
>>
>>
>> -- 
>> Matthew Smith
>> Smiffytech - Technology Consulting & Web Application Development
>> Business: http://www.smiffytech.com/
>> Personal: http://www.smiffysplace.com/
>> LinkedIn: http://www.linkedin.com/in/smiffy
>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Mon, 2 Jun 2008 20:34:43 -0400
>> From: Bob Paddock <bob.paddock at gmail.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <200806022034.44056.bob.paddock at gmail.com>
>> Content-Type: text/plain;  charset="iso-8859-1"
>>
>> On Monday 02 June 2008 02:31:18 pm Patrick wrote:
>>
>>> I have wanted to fabricate my own PCBs for several years now but I have
>>> never made an attempt. I am set up here to do silk screening and I have
>>> ovens and a hot-air soldering iron. Has anyone else tried to fabricate
>>> their own boards or is the price of farming the work out just so low 
>>> now?
>>
>> I've played with doing them at work.  Found it better to just farm them
>> out
>> to the prototype house.  It is tough to get any real consistency from 
>> week
>> to
>> week.
>>
>>> If anyone has farmed out work, could you please feedback as to the entry
>>> level costs and if possible, some suggested companies?
>>
>> Cheapest place I've come across for easy boards with 10mil or large lines
>> is this one, but I've not used them yet (probably next month I will):
>>
>> http://www.futurlec.com/PCBService.shtml
>>
>>> > 1. Surface mount or through hole?  I don't have a re-flow oven (or 
>>> > even
>>> > a
>>> > hot air soldering system), so my inclination is to use through hole
>>
>> SMT is actually easier if you have a good magnifying system.  I use
>> macro-lenses on the wife's Cam-Corder:
>>
>> http://www.designer-iii.com/Solder/  Looks better than the picture of the
>> screen shows in reality.
>>
>> http://www.micromark.com/ has the type of tools that you need, like
>> insulated
>> and cross-tweezers (squeeze them to open them, the reverse of normal
>> tweezers) etc.
>>
>> Pick up a small convection oven at Wal-Mart or such place.
>>
>> If your making several get a Stencil:
>>
>> http://www.smtstencil.com/
>> http://www.customlasercutting.com/
>>
>>>   Will using through hole cause me grief?
>>
>> In the long term, yes.  A lot of older TH parts have not been updated to
>> ROHS
>> (Lead Free) and they never will be, they will be discontinued at some
>> point.
>> Virtually all new parts are SMT.
>>
>>> > 2. How many layers?   In an ideal world with money no object, if I
>>> > understand the current art correctly, I think I'd probably aim for a
>>> > five
>>> > layer
>>
>> I assume that is a typo?  You can not have an odd number of layers.
>> In this current 3D reality each layer has two sides.  :-)
>>
>>> > board with Vcc, Digital Ground and Power Ground being separate
>>> > internal planes, and trace routing on the top and bottom of the board
>>> > with as few vias between top and bottom as possible.  Does that sound
>>> > right?
>>
>> Separate ground planes, or split ground planes are a bad idea in this
>> context.
>> Always think about where the return current is going to flow.
>> Read the Analog Devices seminar notes on the subject.
>>
>> http://www.analog.com/analog_root/static/library/technicalSeminarSeries.html
>> is the link to the books but you can find the chapters on line.
>>
>> Read 7a & 7b if nothing else:
>>
>> http://www.analog.com/en/DCcList/0,3090,1073%255F%255F961,00.html
>>
>>
>> -- 
>>                http://www.wearablesmartsensors.com/
>> http://www.softwaresafety.net/ http://www.designer-iii.com/
>>                 http://www.unusualresearch.com/
>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Tue, 03 Jun 2008 10:08:03 +0930
>> From: Matthew Smith <matt at smiffytech.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <4844926B.6060105 at smiffytech.com>
>> Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>> Quoth Bob Paddock at 2008-06-03 10:04...
>>
>>> Cheapest place I've come across for easy boards with 10mil or large 
>>> lines
>>> is this one, but I've not used them yet (probably next month I will):
>>>
>>> http://www.futurlec.com/PCBService.shtml
>>
>> I was looking at these - they actually do overseas shipments for
>> near-domestic freight prices.  Great for those of us living in countries
>> where board houses require arm, leg and first-born for even small/simple
>> jobs.
>>
>> -- 
>> Matthew Smith
>> Smiffytech - Technology Consulting & Web Application Development
>> Business: http://www.smiffytech.com/
>> Personal: http://www.smiffysplace.com/
>> LinkedIn: http://www.linkedin.com/in/smiffy
>>
>>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Mon, 2 Jun 2008 20:39:02 -0400
>> From: Bob Paddock <bob.paddock at gmail.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <200806022039.02202.bob.paddock at gmail.com>
>> Content-Type: text/plain;  charset="iso-8859-1"
>>
>> On Monday 02 June 2008 04:53:17 pm SAIDJACK at aol.com wrote:
>>
>>> Not the cheapest, but great for "professional" proto's when quality
>>> trumps
>>> cost (above 1GHz, one source FR4 is totally different from another
>>> sources
>>> FR4...)
>>
>> Anyone have suggestions for Metal Core Protype Boards?
>> Used in high power LED applications.
>>
>> I know of this one, are there others?:
>> http://www.protoexpress.com/content/speciality.jsp
>>
>> http://www.cif.fr/new/produits_aff.php3?cat=1&scat=3&sscat=89&p=211
>>
>>
>>
>> ------------------------------
>>
>> Message: 7
>> Date: Mon, 02 Jun 2008 21:05:09 -0400
>> From: Chuck Harris <cfharris at erols.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <484498C5.5030806 at erols.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Bob Paddock wrote:
>>
>>>>> 2. How many layers?   In an ideal world with money no object, if I
>>>>> understand the current art correctly, I think I'd probably aim for a
>>>>> five
>>>>> layer
>>>
>>> I assume that is a typo?  You can not have an odd number of layers.
>>> In this current 3D reality each layer has two sides.  :-)
>>
>>
>> Sure you can.  I have done 3 layer, 5 layer, and 7 layer boards.
>>
>> Having done those, I will advise you not to do 3 layer, it warps.  But
>> everything else is easily do able.
>>
>> Multilayer boards are done by bonding together combinations of
>> 1 side, 2 side, and 0 sided laminate.  For instance:
>>
>> 4 layer can be made by:
>>
>> 2 side | 0 side | 2 side
>> 1 side | 2 side | 1 side
>> 1 side | 1 side | 2 side
>>
>> ...
>>
>> 5 layer can be made by:
>>
>> 2 side | 1 side | 1 side | 1 side
>> 2 side | 0 side | 2 side | 1 side
>> 2 side | 1 side | 0 side | 2 side
>>
>> ...
>>
>> 6 layer can be made by:
>>
>> 2 side | 0 side | 2 side | 0 side | 2 side
>> ...
>>
>> The only down side to odd numbers of layers is the supply house
>> has to stock 1 sided laminate.
>>
>> -Chuck Harris
>>
>>
>>
>> ------------------------------
>>
>> Message: 8
>> Date: Mon, 2 Jun 2008 21:24:21 -0400
>> From: Bob Paddock <bob.paddock at gmail.com>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Message-ID: <200806022124.21583.bob.paddock at gmail.com>
>> Content-Type: text/plain;  charset="iso-8859-1"
>>
>>
>>
>>> How do you cope with SMT parts (eg high frequency ADCs) with metal
>>> thermal transfer /ground connections under the package itself?
>>
>> "How to succeed the first time with ultra-small QFN packages"
>> http://www.wirelessnetdesignline.com/showArticle.jhtml?articleID=202800018
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 9
>> Date: Mon, 2 Jun 2008 18:36:46 -0700
>> From: "Keith Payea" <kpayea at bryantlabs.net>
>> Subject: Re: [time-nuts] PCB design questions thread II
>> To: "'Discussion of precise time and frequency measurement'"
>> <time-nuts at febo.com>
>> Message-ID: <01e001c8c51a$49d9c810$0a01a8c0 at bryant1>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> A really good way to handle the pad on the bottom of the part is to put a
>> hole through the board right there.  You usually need a bunch of vias to
>> tie
>> the pad to the ground plane on the bottom of the board anyway.  Put one
>> hole
>> large enough for your soldering iron tip to reach in and touch the
>> underside
>> of the part.  When installing the part, solder the regular pads first,
>> then
>> flip the board over and solder the central pad.
>>
>> This is sort of self limiting too.  If you apply too much heat for too
>> long,
>> the part desolders itself and falls off!
>>
>> Adding the extra hole is recommended by some of the vendors.  I've used 
>> it
>> sucessfully with 2.4GHz band radios and it works great.
>>
>> Keith
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Bob Paddock
>> Sent: Monday, June 02, 2008 6:24 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] PCB design questions thread II
>>
>>
>>
>>> How do you cope with SMT parts (eg high frequency ADCs) with metal
>>> thermal transfer /ground connections under the package itself?
>>
>> "How to succeed the first time with ultra-small QFN packages"
>> http://www.wirelessnetdesignline.com/showArticle.jhtml?articleID=202800018
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 10
>> Date: Mon, 2 Jun 2008 20:52:56 -0500
>> From: "Didier Juges" <didier at cox.net>
>> Subject: Re: [time-nuts] PCB design questions
>> To: "'Discussion of precise time and frequency measurement'"
>> <time-nuts at febo.com>
>> Message-ID: <012701c8c51c$8c01e630$0a01a8c0 at didierhp>
>> Content-Type: text/plain; charset="windows-1250"
>>
>>
>>
>>> -----Original Message-----
>>> From: time-nuts-bounces at febo.com
>>> [mailto:time-nuts-bounces at febo.com] On Behalf Of David C. Partridge
>>> Sent: Monday, June 02, 2008 1:20 PM
>>> To: 'Discussion of precise time and frequency measurement'
>>> Subject: [time-nuts] PCB design questions
>>>
>>> I've been working on the design for a frequency divider to
>>> complement the Thunderbolt I recently bought from TVB (thank
>>> you Tom, it's working very well as far as I can tell, though
>>> of course I've no other standard to compare against).
>>>
>>
>> Dave,
>>
>> I just made one using a single microcontroller chip soldered on a
>> Toolstick
>> from Silabs. The Toolstick is a small PWB with a small 8051 class
>> microcontroller in surface mount package. The Toolstick costs $10 and you
>> need a $18 programmer to flash it. I run the uC using the 10 MHz as
>> external
>> clock and it has (for now) a 1Hz output.
>>
>> The toolstick I used is similar to the one described on this page:
>>
>> http://www.ko4bb.com/Test_Equipment/AFSignalGenerator/SigGen.php
>>
>> The software is just a couple of for() loops to kill time, a few 2 and 3
>> cycles instructions to adjust the timing perfectly (cannot do NOP from C
>> with the free compiler, but you can program in assembly if you need to
>> feel
>> some pain) and one output is twiddled at the right time. The processor is
>> using the 10 MHz as clock. A single chip is all that is required, the 
>> chip
>> I
>> actually used is a C8051F530-IT, which costs about $4 on the Silabs web
>> site
>> (qty 1) and comes in a 20 pin TSSOP package (surface mount, but 
>> solderable
>> by hand). You really only need to connect 4 pins for that job, supply
>> voltage and ground, 10 MHz input and 1Hz output. Silabs has a couple of
>> parts that are available in DIP package, notably the C8051F330D (refered
>> to
>> as the 330-GP) which is roughly the same core as the 530. If you buy the
>> bare chip, you will have to buy the programmer separately, so if you just
>> want to build a few simple projects, you are better off buying the
>> toolsticks.
>>
>> You might want to add a D flip-flop to clean up the edge, even though I 
>> do
>> not know the jitter of the chip itself (I have planned to test it as well
>> as
>> I can, but there are more projects in the pipe at the moment than time to
>> address them)
>>
>> I am working on a version with both 1 kHz and 1 Hz outputs.
>>
>> There are a few sine-to-square converters (clock shapers) on Bruce's page
>> at
>>
>>
>> http://www.ko4bb.com/~bruce/
>>
>> Didier KO4BB
>>
>> Internal Virus Database is out-of-date.
>> Checked by AVG.
>> Version: 7.5.519 / Virus Database: 269.23.11/1422 - Release Date: 
>> 5/8/2008
>> 5:24 PM
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> time-nuts mailing list
>> time-nuts at febo.com
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>
>> End of time-nuts Digest, Vol 47, Issue 5
>> ****************************************
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 2 Jun 2008 19:26:48 -0700
> From: "John Miles" <jmiles at pop.net>
> Subject: Re: [time-nuts] PCB design questions thread II
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Message-ID: <PKEGJHPHLLBACEOICCBJGENDIEAB.jmiles at pop.net>
> Content-Type: text/plain; charset="us-ascii"
>
>
>> Quoth Bruce Griffiths at 2008-06-03 09:50...
>>
>> > How do you cope with SMT parts (eg high frequency ADCs) with metal
>> > thermal transfer /ground connections under the package itself?
>>
>> Haven't done it myself, but interested to hear others experiences.  I'm
>> guessing that this would be a job for solder paste and a toaster oven -
>> or high-tech equivalent.
>
> Yes, see the link I posted.  Solder paste + heat gun does the trick, or 
> you
> can just carve out a hole for your soldering iron tip with a Dremel tool.
>
> Even BGAs are commonly soldered at home with toaster ovens.
>
> -- john, KE5FX
>
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 03 Jun 2008 14:34:28 +1200
> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> Subject: Re: [time-nuts] time-nuts Digest, Vol 47, Issue 5
> To: Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
> Message-ID: <4844ADB4.3040204 at xtra.co.nz>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Don Collie jnr wrote:
>> I`m curious : What is a "virgin teflon standoff", and does it have 
>> anything
>> to do with the "teflon Don"?
>> ...........................................................................Don
>> C.
>>
>>
> Don
>
> In this context virgin teflon means machined from solid teflon and not
> welded together from grains of teflon.
>
> Bruce
>
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 02 Jun 2008 20:41:46 -0600 (MDT)
> From: "M. Warner Losh" <imp at bsdimp.com>
> Subject: Re: [time-nuts] time-nuts Digest, Vol 47, Issue 5
> To: time-nuts at febo.com, bruce.griffiths at xtra.co.nz
> Message-ID: <20080602.204146.-761023227.imp at bsdimp.com>
> Content-Type: Text/Plain; charset=us-ascii
>
> In message: <4844ADB4.3040204 at xtra.co.nz>
>            Bruce Griffiths <bruce.griffiths at xtra.co.nz> writes:
> : Don Collie jnr wrote:
> : > I`m curious : What is a "virgin teflon standoff", and does it have 
> anything
> : > to do with the "teflon Don"?
> : > 
> ...........................................................................Don
> : > C.
> : >
> : >
> : Don
> :
> : In this context virgin teflon means machined from solid teflon and not
> : welded together from grains of teflon.
>
> I spent about 10 minutes trying to think of a teflon Don or teflon
> coated president joke and couldn't work in a virgin teflon standoff.
> The truth is so, anticlimactic afterwards....
>
> Warner
>
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 2 Jun 2008 19:57:55 -0700
> From: "Prologix" <support at prologix.biz>
> Subject: Re: [time-nuts] PCB design questions thread II
> To: "'Discussion of precise time and frequency measurement'"
> <time-nuts at febo.com>
> Message-ID: <mailman.2647.1212461894.2318.time-nuts at febo.com>
> Content-Type: text/plain; charset="US-ASCII"
>
>
> Another option is to cook the boards in a skillet.
> http://www.sparkfun.com/commerce/present.php?p=Reflow%20Skillet
>
> While John may be brave enough to hand solder BGA I am not :-)
> Shorts can be easily detected with x-ray, but opens can be quite difficult
> to spot.
>
> If you do endup hand soldering BGA, this is a good tool to check shorts 
> and
> opens. That is, if the part is JTAG enabled.
> http://www.macraigor.com/jscan.htm
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of John Miles
> Sent: Monday, June 02, 2008 7:27 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] PCB design questions thread II
>
>
>> Quoth Bruce Griffiths at 2008-06-03 09:50...
>>
>> > How do you cope with SMT parts (eg high frequency ADCs) with metal
>> > thermal transfer /ground connections under the package itself?
>>
>> Haven't done it myself, but interested to hear others experiences.  I'm
>> guessing that this would be a job for solder paste and a toaster oven -
>> or high-tech equivalent.
>
> Yes, see the link I posted.  Solder paste + heat gun does the trick, or 
> you
> can just carve out a hole for your soldering iron tip with a Dremel tool.
>
> Even BGAs are commonly soldered at home with toaster ovens.
>
> -- john, KE5FX
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>
>
> ------------------------------
>
> _______________________________________________
> time-nuts mailing list
> time-nuts at febo.com
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>
> End of time-nuts Digest, Vol 47, Issue 6
> **************************************** 




More information about the time-nuts mailing list