|
DDS kit
I bought one of these kits to make use of a sample AD9851 chip I got
from Analog Devices a few years ago. http://www.amqrp.org/kits/dds60/index.html I knew it was hopeless to bread board something with this chip, but even with a PC board soldering something with such close lead spacing is a challenge (especially when you're past 50 with failing close in vision and less than rock solid stable hands). Still I figured I'd give it a try. Armed with the smallest soldering tip available for my Weller PES51 soldering station, a good magnifier lamp AND a binocular microscope I gave it a try to solder the chip to the board. Well there is good news and bad news. The bad news is that it is impossible to solder the chip by hand without creating solder bridges. The good news is that I did a good enough job to get the chip 99% perfectly centered on the solder pads, and you can remove the solder bridges with solder wick without removing the chip from the PC board. It would have been easier with thiner solder (I had .021" dia solder) and a thiner soldering iron tip, but inspection with the microscope shows no shorts, and it looks like all the pins are properly soldered. Naked eye it doesn't look pretty but it should work. Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). |
DDS kit
In article ,
ken scharf wrote: Well there is good news and bad news. The bad news is that it is impossible to solder the chip by hand without creating solder bridges. The good news is that I did a good enough job to get the chip 99% perfectly centered on the solder pads, and you can remove the solder bridges with solder wick without removing the chip from the PC board. I've seen people recommend this as the preferred hand-soldering approach for dealing with small-pitch surface mount parts. Don't worry about creating bridges... use a bit of liquid flux on the pins, get a nice blob of fresh solder onto the tip of the iron, and then just gently drag the molten solder-ball along the pins and get them soldered to the traces. Then, go back over it with solder-wick and a bit more liquid flux, and wick away the excess. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
DDS kit
Dave Platt wrote:
In article , ken scharf wrote: Well there is good news and bad news. The bad news is that it is impossible to solder the chip by hand without creating solder bridges. The good news is that I did a good enough job to get the chip 99% perfectly centered on the solder pads, and you can remove the solder bridges with solder wick without removing the chip from the PC board. I've seen people recommend this as the preferred hand-soldering approach for dealing with small-pitch surface mount parts. Don't worry about creating bridges... use a bit of liquid flux on the pins, get a nice blob of fresh solder onto the tip of the iron, and then just gently drag the molten solder-ball along the pins and get them soldered to the traces. Then, go back over it with solder-wick and a bit more liquid flux, and wick away the excess. I did smear the pc lands under the chip with paste flux first. Not a heavy coat, just lightly applied. It does help. I've watched the technicians at work hand solder even finer pitch chips. One young woman has very good close in eyesight and works without a magnifier. She does have to clean up with the solder-wick, but makes machine like perfect solder connections. (she makes it look EASY!) Whats hard is doing an entire board in one sitting without getting a visual version of writer's cramp. (eye strain) |
DDS kit
One thing you might try "next time"...
Pre-tin the PC pads by heating them with a heat gun, (being careful to not overheat the board) and applying a very small amount of solder to each pad. If you can get the IC pins all lined up with their PC board pads, tack solder one of the corner pins (or one that is easiest to solder without bridging). Use a toothpick (or some other device) to apply gentle down pressure to the IC to keep it from moving. Use the heat gun again (carefully) until the solder melts and the chip should "settle" down into the molten solder. Keep the heat gun moving around all pins to be sure all get down into molten solder. If you happen to have a piece of copper clad PC board, you can practice by putting some solder blobs on it and putting the leads of some sort of junkbox parts on to the solder and heat it up with the heat gun, apply the down pressure to the component and you can get the feel of how far the heat gun should be away from the board and the length of time it takes to melt the solder... Scott N0EDV ken scharf wrote: I bought one of these kits to make use of a sample AD9851 chip I got from Analog Devices a few years ago. http://www.amqrp.org/kits/dds60/index.html I knew it was hopeless to bread board something with this chip, but even with a PC board soldering something with such close lead spacing is a challenge (especially when you're past 50 with failing close in vision and less than rock solid stable hands). Still I figured I'd give it a try. Armed with the smallest soldering tip available for my Weller PES51 soldering station, a good magnifier lamp AND a binocular microscope I gave it a try to solder the chip to the board. Well there is good news and bad news. The bad news is that it is impossible to solder the chip by hand without creating solder bridges. The good news is that I did a good enough job to get the chip 99% perfectly centered on the solder pads, and you can remove the solder bridges with solder wick without removing the chip from the PC board. It would have been easier with thiner solder (I had .021" dia solder) and a thiner soldering iron tip, but inspection with the microscope shows no shorts, and it looks like all the pins are properly soldered. Naked eye it doesn't look pretty but it should work. Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). |
DDS kit
ken scharf wrote:
Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). It's MUCH easier to begin with the easy parts! Start with the largest chip caps and resistors, continue with the rest of the simple passives, and then the largest ICs (largest pin spacing). Finally, when you've honed your SMD skills, solder the large ICs with the small pin spacings. And give up the industrial-strength coffee for the duration :-) -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
DDS kit
Ian White GM3SEK wrote:
ken scharf wrote: Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). It's MUCH easier to begin with the easy parts! Start with the largest chip caps and resistors, continue with the rest of the simple passives, and then the largest ICs (largest pin spacing). Finally, when you've honed your SMD skills, solder the large ICs with the small pin spacings. And give up the industrial-strength coffee for the duration :-) For some reason the instructions that came with the DDS-60 kit have you solder all the ic's on first, then the resistors and caps. After thinking I had done a good job on the AD9851 I put the board under my binocular microscope for a close in look. I saw what looked like microscopic solder bridges between the chip leads. I was able to remove these with a stiff piece of paper slid between the chip leads. I still see strange 'hair like' structures all over the board under the microscope. I may be seeing dust, bits of flux, who knows! The microscopic world is strange, especially in 3D. |
DDS kit
On 2006-12-28, ken scharf wrote:
I've watched the technicians at work hand solder even finer pitch chips. One young woman has very good close in eyesight and works without a magnifier. She does have to clean up with the solder-wick, but makes machine like perfect solder connections. (she makes it look EASY!) Whats hard is doing an entire board in one sitting without getting a visual version of writer's cramp. (eye strain) After you've done it enough under a microscope you learn what is going to happen and you can do a lot of it without even being able to see it, by timing and feel. Like you said in another post, there's also the part where you get used to how disgusting any solder joint looks under sufficient magnification... -- Ben Jackson AD7GD http://www.ben.com/ |
DDS kit
Personally, I'd do the DDS chip first, before the resistors and
capacitors. One of the tricks I use is to clean the IC pins with rubbing Alcohol after soldering and removing shorts. Then, I apply a hot air gun, SLOWLY bringing the temperature up on the pins of the IC. I try to get to barely melting the solder, but not burning the main board. A slow application allows the IC to heat up gradually. This tends to remove the hairline solder bridges and clean up between the pins of the IC. Since the main DDS chip is the only part on the board, I don't have to worry about heating up and blowing the resistors and capacitors clean off the board !!! I can, and have, used this same method on a completely assembled board, but I have to pay close attention to the small parts, the tend to want to blow away. In that case, I build a heat shield with tin foil and I press it down on the board all around the IC I want to solder flow and that usually keeps the other parts on the board where I want them. This all takes a delicate touch, it's pretty easy to get things too hot, but it does provide nice and clean solder joints. Jim Pennell N6BIU -- 23:10 Pacific Time Zone Dec 28 2006 International Time 07:10 UTC 29.12.2006 |
DDS kit
ken scharf wrote:
I bought one of these kits to make use of a sample AD9851 chip I got from Analog Devices a few years ago. http://www.amqrp.org/kits/dds60/index.html I knew it was hopeless to bread board something with this chip, but even with a PC board soldering something with such close lead spacing is a challenge (especially when you're past 50 with failing close in vision and less than rock solid stable hands). Still I figured I'd give it a try. Armed with the smallest soldering tip available for my Weller PES51 soldering station, a good magnifier lamp AND a binocular microscope I gave it a try to solder the chip to the board. Well there is good news and bad news. The bad news is that it is impossible to solder the chip by hand without creating solder bridges. The good news is that I did a good enough job to get the chip 99% perfectly centered on the solder pads, and you can remove the solder bridges with solder wick without removing the chip from the PC board. It would have been easier with thiner solder (I had .021" dia solder) and a thiner soldering iron tip, but inspection with the microscope shows no shorts, and it looks like all the pins are properly soldered. Naked eye it doesn't look pretty but it should work. Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). Be sure to more or less "drown" the pins to be soldered with flux. If you get solder bridges, you probably have to little flux applied - really slob the flux on the pins. When you think you have enough of flux, add more... Any bridges are corrected with solder wick. The AD98xx can be soldered with a 0.5mm ceramic tip. Get one of these cheap ( 10$ ) magnifying visors, especially if you are half blind as I am... The AD9851 is one of the easiest SMD IC's to solder as there are pins only on two sides. Besides... We have been using SMD's since the early eighties now so stop whinging over it, adapt! They wont go away and they actually improve most RF designs! //Dan, M0DFI |
DDS kit
On Dec 29, 3:37 pm, Dan Andersson wrote: Besides... We have been using SMD's since the early eighties now so stop whinging over it, adapt! They wont go away and they actually improve most RF designs! I've seen some suggestions go around that are very similar to hot-air rework. I just wanted to mention that SparkFun electronics sells some rework stations cheaply, and has useful tutorials on soldering SMD parts. Their site: http://www.sparkfun.com |
DDS kit
wackyvorlon wrote:
On Dec 29, 3:37 pm, Dan Andersson wrote: Besides... We have been using SMD's since the early eighties now so stop whinging over it, adapt! They wont go away and they actually improve most RF designs! I've seen some suggestions go around that are very similar to hot-air rework. I just wanted to mention that SparkFun electronics sells some rework stations cheaply, and has useful tutorials on soldering SMD parts. Their site: http://www.sparkfun.com When you have a proper pc board smt is easy (once you've mastered the new soldering techniques. I had no problem getting the AD9851 onto the board. I think the microscopic hairs I'm seeing are a result of using the solder braid wick. I may have not heated it enough and pulled it off too soon leaving solder hairs behind. Flux sure does help, and I'll use plenty when I solder the next few smt ic's down. I have some smt mounting boards that allow mixing smt parts with through hole on 100 mil grid proto boards. I fear that the extra long leads this adds to the smt parts will make rf performance a problem, especially with 100-400mhz clock signals to the dds chips (AD9951). I've heard of people designing their own pc boards using laser printer output and iron on toner for resit. I've tried this before but with 'bleeding' of the toner during application I don't think I can get better than 50 mil trace separation. Also I've had bad luck etching boards with very thin traces, the traces get etched away before larger areas of copper are finished etching. If I try designing boards for SMT parts I'll probably have to farm them out to a professional house, but this can be expensive for making but one board. (Unless you plan on writing a QST article and selling the extra boards....). |
DDS kit
All of my first year students can hold 20 mil traces and spaces, the C
students can hold 15 mil, and the really good ones can hold 10. Jim I've heard of people designing their own pc boards using laser printer output and iron on toner for resit. I've tried this before but with 'bleeding' of the toner during application I don't think I can get better than 50 mil trace separation. |
DDS kit
On 2006-12-30, ken scharf wrote:
I've heard of people designing their own pc boards using laser printer output and iron on toner for resit. I've tried this before but with 'bleeding' of the toner during application I don't think I can get better than 50 mil trace separation. Print your design on some kind of clay coated paper (people have used everything from magazine pages to photo paper intended for inkjets) and look at the print with a loupe. Cheap laser printers will produce a result full of pinholes. A nice Xerox will make a good, solid black. I haven't had any trouble with toner melting or running. In fact, once you transfer it onto the PCB it's hard to get off! If I try designing boards for SMT parts I'll probably have to farm them out to a professional house, but this can be expensive for making but one board. (Unless you plan on writing a QST article and selling the extra boards....). You've got to pick the right board house for each order. Some, like batchpcb.com, are particularly cheap if you want few, small boards. They don't have setup fees or even per-board fees, only a per-order charge. But their $2.50/in^2 grows faster than some other places which have bigger minimum size boards/minimum orders. -- Ben Jackson AD7GD http://www.ben.com/ |
DDS kit
On Sun, 31 Dec 2006 04:22:42 -0600, Ben Jackson wrote:
You've got to pick the right board house for each order. Some, like batchpcb.com, are particularly cheap if you want few, small boards. They don't have setup fees or even per-board fees, only a per-order charge. But their $2.50/in^2 grows faster than some other places which have bigger minimum size boards/minimum orders. I have been using an off-shore fab for years and they seem to do just what i want, but have setup fees that make protos expensive. So I went and looked at batchpcb.com but they do mention a $US10 setup fee in their FAQ. http://www.batchpcb.com/faq.php?osCs...a389ad75decda8 Do they actually charge it? |
DDS kit
Ben Jackson wrote:
On 2006-12-30, ken scharf wrote: I've heard of people designing their own pc boards using laser printer output and iron on toner for resit. I've tried this before but with 'bleeding' of the toner during application I don't think I can get better than 50 mil trace separation. Print your design on some kind of clay coated paper (people have used everything from magazine pages to photo paper intended for inkjets) and look at the print with a loupe. Cheap laser printers will produce a result full of pinholes. A nice Xerox will make a good, solid black. I haven't had any trouble with toner melting or running. In fact, once you transfer it onto the PCB it's hard to get off! If I try designing boards for SMT parts I'll probably have to farm them out to a professional house, but this can be expensive for making but one board. (Unless you plan on writing a QST article and selling the extra boards....). You've got to pick the right board house for each order. Some, like batchpcb.com, are particularly cheap if you want few, small boards. They don't have setup fees or even per-board fees, only a per-order charge. But their $2.50/in^2 grows faster than some other places which have bigger minimum size boards/minimum orders. My problem with the iron on transfers wasn't being able to print thin, close spaced lines on to the transfer medium. The problem was that when ironed on the toner lines 'spread out' so adjacent lines touched. Also a problem was timing just how long to leave the board in the soup to etch. I did heat the etchant up first and used an IR lamp to try and keep it warm, but even so the thin close spaced traces were close to being over etched long before larger and wider spaced traces were 'done'. (maybe a problem with 'Radio Shack' etchant?) |
DDS kit
RST Engineering wrote:
All of my first year students can hold 20 mil traces and spaces, the C students can hold 15 mil, and the really good ones can hold 10. Yeah, but I'll bet your first year students' eyesight is 30 years younger than that of the average participant in this NGgrin! -- Doug Smith W9WI Pleasant View (Nashville), TN EM66 http://www.w9wi.com (I was a first-year student 29 years ago) |
DDS kit
On 2006-12-31, quandong nut wrote:
I have been using an off-shore fab for years and they seem to do just what i want, but have setup fees that make protos expensive. So I went and looked at batchpcb.com but they do mention a $US10 setup fee in their FAQ. http://www.batchpcb.com/faq.php?osCs...a389ad75decda8 Do they actually charge it? There's a $10 fee per order. But it's not per board or even per design. It's more like a "shipping and handling" fee. So if you keep some boards on file with them you can always throw in a few (smt adapters, or proto boards) with another order for only the sq in cost. -- Ben Jackson AD7GD http://www.ben.com/ |
DDS kit
I've been working on a high-power HF autotuner design that I'd just
about shelved because of the necessity of soldering the DDS chip. (it uses an internal RF source to power the phase detector) This thread has helped a lot. When time permits I may order up some parts and give it a try. I have a good-quality magnifier lamp and a fine-point temp-controlled pencil, what I don't have is OEM eye lenses and flexible finger joints... ;-) Jim, N7CXI ken scharf wrote: Ian White GM3SEK wrote: ken scharf wrote: Now to solder those chip caps and resistors! (They should be easier, the AD9851 was the worst part to place with the tight spacing, all the other parts have lead spacing at least twice as wide). It's MUCH easier to begin with the easy parts! Start with the largest chip caps and resistors, continue with the rest of the simple passives, and then the largest ICs (largest pin spacing). Finally, when you've honed your SMD skills, solder the large ICs with the small pin spacings. And give up the industrial-strength coffee for the duration :-) For some reason the instructions that came with the DDS-60 kit have you solder all the ic's on first, then the resistors and caps. After thinking I had done a good job on the AD9851 I put the board under my binocular microscope for a close in look. I saw what looked like microscopic solder bridges between the chip leads. I was able to remove these with a stiff piece of paper slid between the chip leads. I still see strange 'hair like' structures all over the board under the microscope. I may be seeing dust, bits of flux, who knows! The microscopic world is strange, especially in 3D. |
DDS kit
Jim Barber wrote:
I've been working on a high-power HF autotuner design that I'd just about shelved because of the necessity of soldering the DDS chip. (it uses an internal RF source to power the phase detector) This thread has helped a lot. When time permits I may order up some parts and give it a try. I have a good-quality magnifier lamp and a fine-point temp-controlled pencil, what I don't have is OEM eye lenses and flexible finger joints... ;-) Most of my SMD work is done using half-moon reading glasses - the strongest and cheapest available from the drugstore - in front of my normal glasses. When not in use, they hang from a neck cord. After publishing this suggestion, a very generous person *gave* me a professional-quality binocular microscope. This is wonderful for big jobs like assembling a whole new board... but to be honest, I still tend to use the double glasses more, because the "setup process" is much quicker. You will find that the tip of the soldering iron becomes much steadier when seen under the magnifier. This feedback loop is a wonderful thing, especially if you give it the best possible chance to work: * "Use the scope, Luke!" - learn to concentrate exclusively on what you're SEEING. This is harder than it seems, because for normal soldering we also rely a lot on our sense of touch, and automatically tend to press the tip of the iron against the parts being soldered. With SMD this is a disaster - it simply pushes the parts out of position - so you need to break that habit and concentrate on using ONLY your eyes. * Steady your arm against the edge of the bench, so you're not trying to stabilize your whole body. * Stay off the caffeine - it creates a fine tremor that the brain cannot stabilize (too much "noise" in the feedback loop). -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
DDS kit
Ian White GM3SEK wrote:
Jim Barber wrote: I've been working on a high-power HF autotuner design that I'd just about shelved because of the necessity of soldering the DDS chip. (it uses an internal RF source to power the phase detector) This thread has helped a lot. When time permits I may order up some parts and give it a try. I have a good-quality magnifier lamp and a fine-point temp-controlled pencil, what I don't have is OEM eye lenses and flexible finger joints... ;-) Most of my SMD work is done using half-moon reading glasses - the strongest and cheapest available from the drugstore - in front of my normal glasses. When not in use, they hang from a neck cord. After publishing this suggestion, a very generous person *gave* me a professional-quality binocular microscope. This is wonderful for big jobs like assembling a whole new board... but to be honest, I still tend to use the double glasses more, because the "setup process" is much quicker. You will find that the tip of the soldering iron becomes much steadier when seen under the magnifier. This feedback loop is a wonderful thing, especially if you give it the best possible chance to work: * "Use the scope, Luke!" - learn to concentrate exclusively on what you're SEEING. This is harder than it seems, because for normal soldering we also rely a lot on our sense of touch, and automatically tend to press the tip of the iron against the parts being soldered. With SMD this is a disaster - it simply pushes the parts out of position - so you need to break that habit and concentrate on using ONLY your eyes. The problem with a 10x microscope is first FINDING the soldering iron tip in the field of view. If I am looking into the microscope and trying to place the iron on the work often the iron ends up way in left field (or I push it into my other hand OUCH!) TOO much magnification can be TOO much of a good thing. I wish I had another set of eye piece lenses (or an other objective) so I could go down to 5X sometimes. My microscope is a true binocular with poro prisms and dual objective and eyepiece lenses. It was a 'gift' from a former employer (they were cleaning up the lab and threw it out). I did have to jury rig a stand since only the optic head was found in the trash, the unit originally mounted on a long spring loaded 'gooseneek', like those circleline magnifier lamps. (One of the focus knobs is cracked in half, but I can live with that). * Steady your arm against the edge of the bench, so you're not trying to stabilize your whole body. * Stay off the caffeine - it creates a fine tremor that the brain cannot stabilize (too much "noise" in the feedback loop). Damn Cuban Coffee (Well, I work in Miami!) |
DDS kit
Thanks for the tips, gents.
Sounds like a binocular microscope would be a great tool; otherwise I suspect depth perception might be an issue. I'll keep an eye out for one. Jim, N7CXI ken scharf wrote: Ian White GM3SEK wrote: Jim Barber wrote: I've been working on a high-power HF autotuner design that I'd just about shelved because of the necessity of soldering the DDS chip. (it uses an internal RF source to power the phase detector) This thread has helped a lot. When time permits I may order up some parts and give it a try. I have a good-quality magnifier lamp and a fine-point temp-controlled pencil, what I don't have is OEM eye lenses and flexible finger joints... ;-) Most of my SMD work is done using half-moon reading glasses - the strongest and cheapest available from the drugstore - in front of my normal glasses. When not in use, they hang from a neck cord. After publishing this suggestion, a very generous person *gave* me a professional-quality binocular microscope. This is wonderful for big jobs like assembling a whole new board... but to be honest, I still tend to use the double glasses more, because the "setup process" is much quicker. You will find that the tip of the soldering iron becomes much steadier when seen under the magnifier. This feedback loop is a wonderful thing, especially if you give it the best possible chance to work: * "Use the scope, Luke!" - learn to concentrate exclusively on what you're SEEING. This is harder than it seems, because for normal soldering we also rely a lot on our sense of touch, and automatically tend to press the tip of the iron against the parts being soldered. With SMD this is a disaster - it simply pushes the parts out of position - so you need to break that habit and concentrate on using ONLY your eyes. The problem with a 10x microscope is first FINDING the soldering iron tip in the field of view. If I am looking into the microscope and trying to place the iron on the work often the iron ends up way in left field (or I push it into my other hand OUCH!) TOO much magnification can be TOO much of a good thing. I wish I had another set of eye piece lenses (or an other objective) so I could go down to 5X sometimes. My microscope is a true binocular with poro prisms and dual objective and eyepiece lenses. It was a 'gift' from a former employer (they were cleaning up the lab and threw it out). I did have to jury rig a stand since only the optic head was found in the trash, the unit originally mounted on a long spring loaded 'gooseneek', like those circleline magnifier lamps. (One of the focus knobs is cracked in half, but I can live with that). * Steady your arm against the edge of the bench, so you're not trying to stabilize your whole body. * Stay off the caffeine - it creates a fine tremor that the brain cannot stabilize (too much "noise" in the feedback loop). Damn Cuban Coffee (Well, I work in Miami!) |
DDS kit
Jim Barber wrote:
Thanks for the tips, gents. Sounds like a binocular microscope would be a great tool; otherwise I suspect depth perception might be an issue. It still is an issue, because a microscope prevents you from using one of the most natural ways of perceiving depth, by looking at the board from a few different angles. Only a head-mounted viewer allows this. A large lens on a spring arm is a kind of half-way option, but it rapidly loses quality at off-axis angles. Another problem that needs to be mentioned is focusing and depth of focus. With a microscope, you have to put down the iron or the solder in order to adjust the focus. With a head-mounted viewer, you simply move your head to re-focus... but by the end of the day you'll probably have neck strain. Also we haven't mentioned lighting. All microscopes tend to suffer from poor light-gathering power, so the work area needs to be very brightly lit. While we're on the subject, a friend has come up with yet another option. Like many of us, he has a very good detachable zoom lens for a 35mm camera that he doesn't use any more. He has fixed this onto a low-cost colour CCTV camera, and positioned it about 4 feet above the workbench, looking straight down. This gives a moderately magnified view of the work area on a TV monitor directly in front of him. This has the big advantage of leaving the workspace completely unobstructed, so he can switch very easily and naturally between the monitor and the direct view. He reports that it avoids a lot of the eye and neck strain. The main practical problem that he still has to solve is "camera shake", because of viewing from such a long distance. In his case, the camera is mounted from the roof of a wooden shack, so he can't do SMD work on a windy day. If you have a suitable lens and a CCTV camera, this option would be well worth trying. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
DDS kit
Now that has potential:
By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Jim, N7CXI Ian White GM3SEK wrote: Jim Barber wrote: Thanks for the tips, gents. Sounds like a binocular microscope would be a great tool; otherwise I suspect depth perception might be an issue. It still is an issue, because a microscope prevents you from using one of the most natural ways of perceiving depth, by looking at the board from a few different angles. Only a head-mounted viewer allows this. A large lens on a spring arm is a kind of half-way option, but it rapidly loses quality at off-axis angles. Another problem that needs to be mentioned is focusing and depth of focus. With a microscope, you have to put down the iron or the solder in order to adjust the focus. With a head-mounted viewer, you simply move your head to re-focus... but by the end of the day you'll probably have neck strain. Also we haven't mentioned lighting. All microscopes tend to suffer from poor light-gathering power, so the work area needs to be very brightly lit. While we're on the subject, a friend has come up with yet another option. Like many of us, he has a very good detachable zoom lens for a 35mm camera that he doesn't use any more. He has fixed this onto a low-cost colour CCTV camera, and positioned it about 4 feet above the workbench, looking straight down. This gives a moderately magnified view of the work area on a TV monitor directly in front of him. This has the big advantage of leaving the workspace completely unobstructed, so he can switch very easily and naturally between the monitor and the direct view. He reports that it avoids a lot of the eye and neck strain. The main practical problem that he still has to solve is "camera shake", because of viewing from such a long distance. In his case, the camera is mounted from the roof of a wooden shack, so he can't do SMD work on a windy day. If you have a suitable lens and a CCTV camera, this option would be well worth trying. |
DDS kit
On Mon, 08 Jan 2007 12:18:36 -0800, Jim Barber wrote in :
Now that has potential: By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Jim, N7CXI One can find similar devices on the used market from time to time, made for folks who are visually-impaired. My late wife left me one, but it's up in Canada. I hope to retrieve it this coming summer. -- "The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary." -- James D. Nicoll |
DDS kit
Jim Barber wrote:
Now that has potential: By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Not my own idea, but a friend's. He particularly likes having the camera a long way above the work, so the area in front of him is completely clear. Come to think, my dentist has very a similar system as part of his fancy new workstation, which is styled like the bridge of the Starship Enterprise. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
DDS kit
"Ian White GM3SEK" wrote in message ... Jim Barber wrote: Now that has potential: By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Not my own idea, but a friend's. He particularly likes having the camera a long way above the work, so the area in front of him is completely clear. Come to think, my dentist has very a similar system as part of his fancy new workstation, which is styled like the bridge of the Starship Enterprise. Speaking of the dentist, I visited the dentist yesterday and quizzed the hygienist about her glasses with the special lenses mounted out front. She said the had a magnification of 2.5 and focus length around 18". Always thought I wanted a pair of those but 2.5 magnification doesn't seem like enough and she reported the cost as $800.00. The dentist had a flip down style that mounted to his regular glasses. They cost less but still expensive. Mike |
DDS kit
amdx wrote:
"Ian White GM3SEK" wrote in message ... Jim Barber wrote: Now that has potential: By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Not my own idea, but a friend's. He particularly likes having the camera a long way above the work, so the area in front of him is completely clear. Come to think, my dentist has very a similar system as part of his fancy new workstation, which is styled like the bridge of the Starship Enterprise. Speaking of the dentist, I visited the dentist yesterday and quizzed the hygienist about her glasses with the special lenses mounted out front. She said the had a magnification of 2.5 and focus length around 18". Always thought I wanted a pair of those but 2.5 magnification doesn't seem like enough and she reported the cost as $800.00. The dentist had a flip down style that mounted to his regular glasses. They cost less but still expensive. I should have said that the TV camera was mostly for the education and amusement(?) of the patients, and to allow images to be captured for the records. For his own use, my dentist has exactly the same kinds of flip-up compound lenses that give a reasonably magnified view from a long focal distance. This allows him to sit more upright and avoid back strain. Such lenses would be fine for SMD work too, because they would give us an unobstructed work area, and would reduce back and neck strain for us too. But as you say, they are low on magnification for our needs, and very expensive. People's eyes and preferences vary, so there's no one 'best' magnification. Personally I find x10 is plenty for SMD, and might even trade down to x5 for a system that gave me more clear space to wave the soldering iron... and of course if the price was right. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
DDS kit
I use these:
http://www.harborfreight.com/cpi/cta...emnumber=38896 Also, I've soldered literally hundreds of fine-pitch SMD ICs using the simplest method of all: just bridge all the pins with solder and wick off the excess with solder-wick. Never had any problems with residual solder bridging or whiskers of solder-wick. You folks have made a mountain out of a molehill on this subject. Joe W3JDR "amdx" wrote in message ... "Ian White GM3SEK" wrote in message ... Jim Barber wrote: Now that has potential: By pure coincidence, I already have a Sony HDR-SR1 high-def (1080i) camcorder and a 21" 16:9 LCD display with HDMI input in the lab. Putting those two devices together and adding an appropriate macro lens would seem to be a natural thing for this kind of work. Great idea, Ian! Not my own idea, but a friend's. He particularly likes having the camera a long way above the work, so the area in front of him is completely clear. Come to think, my dentist has very a similar system as part of his fancy new workstation, which is styled like the bridge of the Starship Enterprise. Speaking of the dentist, I visited the dentist yesterday and quizzed the hygienist about her glasses with the special lenses mounted out front. She said the had a magnification of 2.5 and focus length around 18". Always thought I wanted a pair of those but 2.5 magnification doesn't seem like enough and she reported the cost as $800.00. The dentist had a flip down style that mounted to his regular glasses. They cost less but still expensive. Mike |
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