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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Using magnets with tiny SMD devices - any electronic concerns?
At the moment only diodes , but what about more sophisticated stuff?
Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. |
#2
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Using magnets with tiny SMD devices - any electronic concerns?
On Friday, March 24, 2017 at 11:30:32 AM UTC-4, N_Cook wrote:
At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. I cannot imagine stray magnetism to be a concern for SMD devices these days. And given how many times very, very powerful magnets are used for cleaning materials and separating contamination artifacts from parts. That being written: a) There are magnet-based pick-and-place devices deployed for SMD devices already. b) There are magnetic clamping and holding devices already deployed for boards and other parts. Their outstanding virtue is no moving parts. NOTE: Reed and other sensitive mechanical relays using internal magnets may be damaged by excessive stray fields. So keep that in mind. Otherwise, have-at. http://hackaday.com/2011/02/24/magne...ick-and-place/ Peter Wieck Melrose Park, PA |
#3
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Using magnets with tiny SMD devices - any electronic concerns?
On Fri, 24 Mar 2017, N_Cook wrote:
At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. WOuldn't an electromagnet be better? So you can turn it on as needed? The good magnets are great, but lots of trouble removing them from something. Michael |
#4
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Using magnets with tiny SMD devices - any electronic concerns?
On Friday, March 24, 2017 at 4:02:07 PM UTC-4, Michael Black wrote:
On Fri, 24 Mar 2017, N_Cook wrote: At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. WOuldn't an electromagnet be better? So you can turn it on as needed? The good magnets are great, but lots of trouble removing them from something. Michael There is that, of course. And with neodymium magnets, switching them "off" is difficult. I was addressing the concept of magnetic fields in the first place. I would also suggest AC on the electromagnet as that will naturally de-magnetize anything it touches - cf.: tape-head demagnetizers. Peter Wieck Melrose Park, PA |
#5
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Using magnets with tiny SMD devices - any electronic concerns?
On 24/03/2017 15:30, N_Cook wrote:
At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. While at it, any problems with fine chip geometries in cameras, fancy phones and computers, passing through airport X-ray scanners? |
#6
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Using magnets with tiny SMD devices - any electronic concerns?
I have been through many scanners all over the US, and the world. No issues, ever. Traveling with everything from high end cameras to sensitive medical equipment.
Peter Wieck Melrose Park, PA |
#7
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Using magnets with tiny SMD devices - any electronic concerns?
On Friday, March 24, 2017 at 1:31:11 PM UTC-7, wrote:
On Friday, March 24, 2017 at 4:02:07 PM UTC-4, Michael Black wrote: On Fri, 24 Mar 2017, N_Cook wrote: At the moment only diodes , but what about more sophisticated stuff? Any devices a definite no-no for high local magnetism? WOuldn't an electromagnet be better? So you can turn it on as needed? There is that, of course. And with neodymium magnets, switching them "off" is difficult. I was addressing the concept of magnetic fields in the first place. I would also suggest AC on the electromagnet as that will naturally de-magnetize anything it touches - cf.: tape-head demagnetizers. I second this. It concerns me somewhat that the magnetic components might realign themselves when you drop 'em, too; does anyone remember that silly little toy with magetized Scottie dogs? Accidental magnetization can affect a relay or buzzer, but is unlikely to have any permanent effect on the mainly-nickel magnetizables on surface mount devices.. The worst I can imagine, is that a ferrite might leap to the magnet face and get a fracture from the impact. |
#8
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Using magnets with tiny SMD devices - any electronic concerns?
On 3/26/2017 3:29 PM, whit3rd wrote:
On Friday, March 24, 2017 at 1:31:11 PM UTC-7, wrote: On Friday, March 24, 2017 at 4:02:07 PM UTC-4, Michael Black wrote: On Fri, 24 Mar 2017, N_Cook wrote: At the moment only diodes , but what about more sophisticated stuff? Any devices a definite no-no for high local magnetism? WOuldn't an electromagnet be better? So you can turn it on as needed? There is that, of course. And with neodymium magnets, switching them "off" is difficult. I was addressing the concept of magnetic fields in the first place. I would also suggest AC on the electromagnet as that will naturally de-magnetize anything it touches - cf.: tape-head demagnetizers. I'd worry a lot about that. Transients from turning the electromagnet on and off can create voltage in nearby conductors. Sensitive inputs might not like that. Hall Effect sensors might not like magnetism either. I second this. It concerns me somewhat that the magnetic components might realign themselves when you drop 'em, too; does anyone remember that silly little toy with magetized Scottie dogs? Accidental magnetization can affect a relay or buzzer, but is unlikely to have any permanent effect on the mainly-nickel magnetizables on surface mount devices.. The worst I can imagine, is that a ferrite might leap to the magnet face and get a fracture from the impact. |
#9
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Using magnets with tiny SMD devices - any electronic concerns?
On 27/03/2017 02:17, mike wrote:
On 3/26/2017 3:29 PM, whit3rd wrote: On Friday, March 24, 2017 at 1:31:11 PM UTC-7, wrote: On Friday, March 24, 2017 at 4:02:07 PM UTC-4, Michael Black wrote: On Fri, 24 Mar 2017, N_Cook wrote: At the moment only diodes , but what about more sophisticated stuff? Any devices a definite no-no for high local magnetism? WOuldn't an electromagnet be better? So you can turn it on as needed? There is that, of course. And with neodymium magnets, switching them "off" is difficult. I was addressing the concept of magnetic fields in the first place. I would also suggest AC on the electromagnet as that will naturally de-magnetize anything it touches - cf.: tape-head demagnetizers. I'd worry a lot about that. Transients from turning the electromagnet on and off can create voltage in nearby conductors. Sensitive inputs might not like that. Hall Effect sensors might not like magnetism either. I second this. It concerns me somewhat that the magnetic components might realign themselves when you drop 'em, too; does anyone remember that silly little toy with magetized Scottie dogs? Accidental magnetization can affect a relay or buzzer, but is unlikely to have any permanent effect on the mainly-nickel magnetizables on surface mount devices.. The worst I can imagine, is that a ferrite might leap to the magnet face and get a fracture from the impact. Perhaps not the voltage as such, but potentially destructive high dV/dt , lowish voltage but very short duration |
#10
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Using magnets with tiny SMD devices - any electronic concerns?
On Sunday, March 26, 2017 at 9:18:50 PM UTC-4, mike wrote:
I'd worry a lot about that. Transients from turning the electromagnet on and off can create voltage in nearby conductors. Sensitive inputs might not like that. Hall Effect sensors might not like magnetism either. Good to raise the question - which deserves an answer that addresses it directly. Magnetic fields are largely dissipated when bridged. Which is why horseshoe magnets, as one obvious example are bridged when shipped. A bar between N & S., that is. DO try this at home. Take the typical cartoon-type horseshoe magnet and iron filings (in a bag for the purposes of neatness). With the bar and without the bar. When a magnetic parts-picker is holding its part, it is bridged. The electromotive coil is sitting between the two poles which are gapped at the proper size to pick up the part in question. The part-in-place dissipates extraneous fields, is demagnetized by the shifting field applied to it, and when the system shuts off (dropping the part) also absorbs and dissipates the transient - which ain't much nohow, anyway. Thank goodness for high-school science. We learned things as they apply to real life every single day. And a lot of cool stuff, too. Such as making gunpowder (elementary), gun cotton (nitrocellulose, not so easy) and much more. The teacher ran the course parallel to our history courses with a little bit of physics thrown in. So, we made "Egyptian Ice" in hot weather, a Rhodesian hoist, Prince Rupert's drops, Archimedes' screw (as well as displacement and specific gravity experiments, split rocks without tools, and much much more. Teaching that kind of science is probably a lost art - who would let little Jilly or Johnny around glacial sulphuric acid, much less the 'fixins' for gunpowder these days? But I can tell you exactly how a Lift Pump works, how it is different from a Force Pump, and its lifting limits. And we learned about the differences between the Atkinson cycle and the Otto cycle in 1967. As well as the ten (10) reindeer... How you can tell an American anywhere under any conditions... much longer, but related stories. The former is disclosable to the general public, the latter not - for obvious reasons. Peter Wieck Melrose Park, PA |
#11
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Using magnets with tiny SMD devices - any electronic concerns?
On 25/03/2017 02:30, N_Cook wrote:
At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. Some RF ferrites probably wouldn't like it. I remember reading warnings about that. I doubt you would encounter those often. |
#12
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Using magnets with tiny SMD devices - any electronic concerns?
On 26/03/2017 05:55, N_Cook wrote:
On 24/03/2017 15:30, N_Cook wrote: At the moment only diodes , but what about more sophisticated stuff? Required a way of holding 2 of the tiniest (2mm long dimension) SMD devices in registration , to solder together . Used a 6 pole rare earth magnet from a VCR motor. Also broke a chip off to epoxy to the end of a matchstick as a manipulator, for transfering to pcb and holding in place while first solder dab. Any devices a definite no-no for high local magnetism? , presumably some SMD termination metal is not ferrous for one thing. While at it, any problems with fine chip geometries in cameras, fancy phones and computers, passing through airport X-ray scanners? http://www.intersil.com/content/dam/...n15/an1533.pdf |
#13
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Using magnets with tiny SMD devices - any electronic concerns?
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#14
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Using magnets with tiny SMD devices - any electronic concerns?
OK - a few things.
a) Airport and shipping security are facts of life whether one is from the back of beyond or downtown NYC. Every manufacturer on the planet understands this. b) Older devices would simply be immune to stray fields of the sorts found in airports, flying above 5,000 feet (cosmic rays), walking down the street (how many cell/bluetooth devices/routers/GPS devices and more do you think you are passing in, around and through on a moment-to-moment basis? Newer devices would be designed to be immune. After all, we are not discussing EMPs, just stray fields. c) Magnetic fields propagate by the inverse-square. Twice the distance = the ˆš of the first distance. And so forth. d) As previously noted, the magnetic field is bridged, and alternating. e) As previously noted, the field is released when the part is placed - so there is no, repeat, no induced field beyond the shield (part) itself. And as all sorts of these devices are already deployed all over the planet in many configurations without apparent untoward effects as of yet, I suggest that the need for paranoia is minimal. https://www.youtube.com/watch?v=gp5JCrSXkJY Peter Wieck Melrose Park, PA |
#15
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Using magnets with tiny SMD devices - any electronic concerns?
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#16
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Using magnets with tiny SMD devices - any electronic concerns?
On Saturday, April 1, 2017 at 12:02:43 PM UTC-4, Michael Terrell wrote:
The tools to pick up SMD components use vacuum. Both manual, and Pick-N-Place machines. Not all of them. http://hackaday.com/2011/02/24/magne...ick-and-place/ Peter Wieck Melrose Park, PA |
#18
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Using magnets with tiny SMD devices - any electronic concerns?
It ain't nohow the only one.
Peter Wieck Melrose Park, PA |
#19
Posted to sci.electronics.repair,sci.electronics.design
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Using magnets with tiny SMD devices - any electronic concerns?
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