Forums

MicroZED

Started by John Larkin October 19, 2013
On 10/22/2013 11:47 AM, John Larkin wrote:
> On Tue, 22 Oct 2013 10:48:09 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 10/22/2013 10:38 AM, Joerg wrote: >>> John Larkin wrote: >>>> On Mon, 21 Oct 2013 14:25:56 -0500, Jon Elson <jmelson@wustl.edu> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>> >>>>> >>>>>> We prefer BGAs to leaded parts. >>>>> OK, well, someday, I'm sure, I will be led kicking and screaming down >>>>> that path. The lack of ability to examine the solder balls worries me. >>>> >>>> The great thing about inspecting all those BGA balls is that you can't >>>> inspect them. >>>> >>> >>> That's why inspection is usually not done :-( >>> >>> >>>> Actually, there are some optical gadgets that let you peek under the >>>> chip, from the side, and see the first 3 or 4 rows of balls fairly >>>> well. And you can see through the entire array, for debris and such. >>>> We just bought a good one for around $30K. >>>> >>> >>> Can it reliably detect flux residue somewhere in the middle? It's hard >>> to clean under a large BGA and then a few years down the road something >>> might quit working. >>> >>> >>>>> I do all my own assembly using an aging P&P machine and a modified >>>>> toaster oven. >>>> >>>> People do BGAs at home, too. >>>> >>>> These are cool: >>>> >>>> http://www.stencilsunlimited.com/bga_rework_stencils_stencilquik.php >>>> >>>> We use them for rework, but they would be good for hand assembly, too. >>>> >>> >>> How do you get the flux back out? Do you use Kester 951 flux? >>> >>> >>>> I have overcome my fears of 1206s, 0805s, 0603s, SC70s and US8 >>>> packages (almost), TSSOPs, and BGAs. SC79s and 0402s still terrify me. >>>> >>> >>> Those are boulders. Some time around March next year I'll have to deal >>> with 01005. Not looking forward to that but as John Wayne said, man's >>> gotta do what man's gotta do. >>> >>> As I get older and SMT becomes smaller I have found that even the >>> Donegan 5x visor is sometimes not enough. >>> >> >> Big BGAs need underfill to reduce the stress on the balls. > > Would a thin layer of epoxy or whatever add any substantial strength to a > thousand soldered balls? How would you get it in there? > > We've had zero ball-joint failures in the field, must be many billion ball-hours > so far. > > >
Underfill makes a huge difference, like a factor of two in chip size for a given reliability. IBM uses lots of giant BGAs. They invented the ball grid array back around 1980, for the 3081 mainframe. The local name is C4, which has nothing to do with plastic explosives, but stands for Controlled Collapse Chip Connect. (I think the collapse that's in view is the solder balls coalescing with the solder on the board.) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
On Tue, 22 Oct 2013 14:32:38 -0500, Jon Elson <jmelson@wustl.edu>
wrote:

>John Larkin wrote: > > >> I have overcome my fears of 1206s, 0805s, 0603s, SC70s and US8 >> packages (almost), TSSOPs, and BGAs. SC79s and 0402s still terrify me. > >It took me a while to get the hang of TSSOP, but now those are pretty >much standard. I do automated placement and mass reflow of those >with only a little trouble. I've stuck to 0805 passives, as there >is not that much advantage to me to go smaller. (For microwave >or high speed stuff, there may be electrical advantages, but I'm not >in that regime.) I had a real bad experience with a chip-scale comparator >(AD CMP603) that was only available in that package, had 65 on each board, >and massive number of shorts under the chips. Soured me on the whole >concept.
0402s are a big win for QFP terminators and pull-downs. They also make great differential pads and filters. Two 0402 resistors and a 0603 cap lay out very nicely on QFP spacing. Of course, 0402s are our standard. They're cheaper, too.
On 10/22/2013 12:21 PM, Joerg wrote:
> John Larkin wrote: >> On Tue, 22 Oct 2013 07:38:58 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> John Larkin wrote: >>>> On Mon, 21 Oct 2013 14:25:56 -0500, Jon Elson <jmelson@wustl.edu> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>> > > [...] > >>> >>>> Actually, there are some optical gadgets that let you peek under the >>>> chip, from the side, and see the first 3 or 4 rows of balls fairly >>>> well. And you can see through the entire array, for debris and such. >>>> We just bought a good one for around $30K. >>>> >>> Can it reliably detect flux residue somewhere in the middle? It's hard >>> to clean under a large BGA and then a few years down the road something >>> might quit working. >> >> It can see down the rows pretty well, so it would see a clump of flux, or some >> stray solder balls. We use rosin flux, so we aren't concerned about leakage and >> corrosion, like you might be with water soluble fluxes. >> >> We've found BGAs to be extremely reliable, both initially and in the field, way >> better than fine-pitch leaded parts. And there's no other way to get 780 or 1120 >> pins on a chip. >> > > BGA's fare a lot better in equipment that is mostly stationary. Less so > where things move or vibrate a lot. But yeah, if you absolutely need > many hundreds of connections there may be no choice. > >>> >>>>> I do all my own assembly using an aging P&P machine and a modified >>>>> toaster oven. >>>> People do BGAs at home, too. >>>> >>>> These are cool: >>>> >>>> http://www.stencilsunlimited.com/bga_rework_stencils_stencilquik.php >>>> >>>> We use them for rework, but they would be good for hand assembly, too. >>>> >>> How do you get the flux back out? Do you use Kester 951 flux? >> >> We don't. Rosin flux residue doesn't do any harm. >> > > I think that depends on the halides in there. > >> >>> >>>> I have overcome my fears of 1206s, 0805s, 0603s, SC70s and US8 >>>> packages (almost), TSSOPs, and BGAs. SC79s and 0402s still terrify me. >>>> >>> Those are boulders. Some time around March next year I'll have to deal >>> with 01005. Not looking forward to that but as John Wayne said, man's >>> gotta do what man's gotta do. >> >> Don't you ever get the feeling that playing with tiny parts on circuit boards >> isn't, well, a very macho way to make a living? Shouldn't we be out there >> chopping down trees or running ships aground or something? But on cold rainy >> days, I appreciate electronics more. >> > > To compensate for that I just dusted off my old mountain bike and ride > it after lunch. Those big tires feel very manly and make a manly noise > on paved roads. The main reason is that I found that a brisk 30-45min > walk every morning is not enough to keep the weight off. Seems the fuel > efficiency of a human goes up with age. > > >>> As I get older and SMT becomes smaller I have found that even the >>> Donegan 5x visor is sometimes not enough. >> >> As the parts get smaller, everybody needs optics. >> >> Reconsider a Mantis. If you set the IPD knob to match your anatomy, they are >> comfortable and the view is stunning. And you don't have to hunch over like you >> do with a visor. >> > > I don't have space for a Mantis here, mostly because I sometimes have > very large prototypes on the lab bench. There can't be anything big and > heavy in the way. When I want to avoid the hunch I use a Veho 20x USB > microscope. A Supereyes 500x if it gets really small but that one > doesn't allow several inches of vertical work space. Those are cheap > "toy scopes" but they work quite well. As I said before, the good old > days are today. >
I'm hoping to be able to get a Mitutoyo FS110 microscope, but I need a bit more bench space first. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Phil Hobbs wrote:
> On 10/22/2013 12:21 PM, Joerg wrote: >> John Larkin wrote: >>> On Tue, 22 Oct 2013 07:38:58 -0700, Joerg <invalid@invalid.invalid> >>> wrote: >>>
[...]
>>>> As I get older and SMT becomes smaller I have found that even the >>>> Donegan 5x visor is sometimes not enough. >>> >>> As the parts get smaller, everybody needs optics. >>> >>> Reconsider a Mantis. If you set the IPD knob to match your anatomy, >>> they are >>> comfortable and the view is stunning. And you don't have to hunch >>> over like you >>> do with a visor. >>> >> >> I don't have space for a Mantis here, mostly because I sometimes have >> very large prototypes on the lab bench. There can't be anything big and >> heavy in the way. When I want to avoid the hunch I use a Veho 20x USB >> microscope. A Supereyes 500x if it gets really small but that one >> doesn't allow several inches of vertical work space. Those are cheap >> "toy scopes" but they work quite well. As I said before, the good old >> days are today. >> > > I'm hoping to be able to get a Mitutoyo FS110 microscope, but I need a > bit more bench space first. >
For me it's not just bench space, I'd have to get more office space first. And I really don't want to move out from here because I thoroughly enjoy working from the house. Almost zero commute time, anytime I can take a break can be family time, on rainy days we can start a dog walk the millisecond it clears up, the younger Labrador checks on my work every 20 minutes, and so on. -- Regards, Joerg http://www.analogconsultants.com/
Joerg wrote:
For me it's not just bench space, I'd have to get more office space 
first. And I really don't want to move out from here because I 
thoroughly enjoy working from the house. Almost zero commute time, 
anytime I can take a break can be family time, on rainy days we can 
start a dog walk the millisecond it clears up, the younger Labrador 
checks on my work every 20 minutes, and so on.
---
 
Frequent breaks like that are really good for your health, too.
No real estate to expand buildings onto?
Greegor wrote:
> Joerg wrote: > For me it's not just bench space, I'd have to get more office space > first. And I really don't want to move out from here because I > thoroughly enjoy working from the house. Almost zero commute time, > anytime I can take a break can be family time, on rainy days we can > start a dog walk the millisecond it clears up, the younger Labrador > checks on my work every 20 minutes, and so on. > --- > > Frequent breaks like that are really good for your health, too. > No real estate to expand buildings onto?
Nope. Plus getting a building permit in this area has become next to impossible. It took our church more than five (!) years for an education building and a ballfield, despite the fact that we declared it open for use by the whole community. -- Regards, Joerg http://www.analogconsultants.com/
On Tue, 22 Oct 2013 09:21:45 -0700, Joerg <invalid@invalid.invalid>
wrote:

>John Larkin wrote: >> On Tue, 22 Oct 2013 07:38:58 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> John Larkin wrote: >>>> On Mon, 21 Oct 2013 14:25:56 -0500, Jon Elson <jmelson@wustl.edu> >>>> wrote: >>>> >>>>> John Larkin wrote: >>>>> > >[...] > >>> >>>> Actually, there are some optical gadgets that let you peek under the >>>> chip, from the side, and see the first 3 or 4 rows of balls fairly >>>> well. And you can see through the entire array, for debris and such. >>>> We just bought a good one for around $30K. >>>> >>> Can it reliably detect flux residue somewhere in the middle? It's hard >>> to clean under a large BGA and then a few years down the road something >>> might quit working. >> >> It can see down the rows pretty well, so it would see a clump of flux, or some >> stray solder balls. We use rosin flux, so we aren't concerned about leakage and >> corrosion, like you might be with water soluble fluxes. >> >> We've found BGAs to be extremely reliable, both initially and in the field, way >> better than fine-pitch leaded parts. And there's no other way to get 780 or 1120 >> pins on a chip. >> > >BGA's fare a lot better in equipment that is mostly stationary. Less so >where things move or vibrate a lot. But yeah, if you absolutely need >many hundreds of connections there may be no choice. > >>> >>>>> I do all my own assembly using an aging P&P machine and a modified >>>>> toaster oven. >>>> People do BGAs at home, too. >>>> >>>> These are cool: >>>> >>>> http://www.stencilsunlimited.com/bga_rework_stencils_stencilquik.php >>>> >>>> We use them for rework, but they would be good for hand assembly, too. >>>> >>> How do you get the flux back out? Do you use Kester 951 flux? >> >> We don't. Rosin flux residue doesn't do any harm. >> > >I think that depends on the halides in there. > >> >>> >>>> I have overcome my fears of 1206s, 0805s, 0603s, SC70s and US8 >>>> packages (almost), TSSOPs, and BGAs. SC79s and 0402s still terrify me. >>>> >>> Those are boulders. Some time around March next year I'll have to deal >>> with 01005. Not looking forward to that but as John Wayne said, man's >>> gotta do what man's gotta do. >> >> Don't you ever get the feeling that playing with tiny parts on circuit boards >> isn't, well, a very macho way to make a living? Shouldn't we be out there >> chopping down trees or running ships aground or something? But on cold rainy >> days, I appreciate electronics more. >> > >To compensate for that I just dusted off my old mountain bike and ride >it after lunch. Those big tires feel very manly and make a manly noise >on paved roads. The main reason is that I found that a brisk 30-45min >walk every morning is not enough to keep the weight off. Seems the fuel >efficiency of a human goes up with age. > > >>> As I get older and SMT becomes smaller I have found that even the >>> Donegan 5x visor is sometimes not enough. >> >> As the parts get smaller, everybody needs optics. >> >> Reconsider a Mantis. If you set the IPD knob to match your anatomy, they are >> comfortable and the view is stunning. And you don't have to hunch over like you >> do with a visor. >> > >I don't have space for a Mantis here, mostly because I sometimes have >very large prototypes on the lab bench. There can't be anything big and >heavy in the way. When I want to avoid the hunch I use a Veho 20x USB >microscope. A Supereyes 500x if it gets really small but that one >doesn't allow several inches of vertical work space. Those are cheap >"toy scopes" but they work quite well. As I said before, the good old >days are today.
My bench isn't very big either. My Mantis doesn't take much room. It tucks away when I'm not using it. And it can swing over/into pretty big rackmount boxes. https://dl.dropboxusercontent.com/u/53724080/Mantis/Mantis_Box.JPG -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Joerg wrote:

> There is a whole little industry that sprung up when BGAs were > introduced. People learned re-balling and other things and then repaired > game consoles, expensive laptops and such.
Exactly -- never heard of "repinning", while "reballing" is quite popular :-> Best regards, Piotr
John Larkin wrote:
> On Tue, 22 Oct 2013 09:21:45 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Tue, 22 Oct 2013 07:38:58 -0700, Joerg <invalid@invalid.invalid> wrote:
[...]
>>>> As I get older and SMT becomes smaller I have found that even the >>>> Donegan 5x visor is sometimes not enough. >>> As the parts get smaller, everybody needs optics. >>> >>> Reconsider a Mantis. If you set the IPD knob to match your anatomy, they are >>> comfortable and the view is stunning. And you don't have to hunch over like you >>> do with a visor. >>> >> I don't have space for a Mantis here, mostly because I sometimes have >> very large prototypes on the lab bench. There can't be anything big and >> heavy in the way. When I want to avoid the hunch I use a Veho 20x USB >> microscope. A Supereyes 500x if it gets really small but that one >> doesn't allow several inches of vertical work space. Those are cheap >> "toy scopes" but they work quite well. As I said before, the good old >> days are today. > > My bench isn't very big either. My Mantis doesn't take much room. It > tucks away when I'm not using it. And it can swing over/into pretty > big rackmount boxes. > > https://dl.dropboxusercontent.com/u/53724080/Mantis/Mantis_Box.JPG >
That's too big for me. My main lab bench is a large angled bench where one wing has a big equipment rack and the other needs to remain free from three side. It is a very heavy duty bench that can (and sometimes has to) take loads where the one in your picture would probably get bent in the frame or where it would snap the wood. -- Regards, Joerg http://www.analogconsultants.com/
Den onsdag den 23. oktober 2013 15.04.46 UTC+2 skrev Joerg:
> John Larkin wrote: > > > On Tue, 22 Oct 2013 09:21:45 -0700, Joerg <invalid@invalid.invalid> > > > wrote: > > > > > >> John Larkin wrote: > > >>> On Tue, 22 Oct 2013 07:38:58 -0700, Joerg <invalid@invalid.invalid> wrote: > > > > [...] > > > > >>>> As I get older and SMT becomes smaller I have found that even the > > >>>> Donegan 5x visor is sometimes not enough. > > >>> As the parts get smaller, everybody needs optics. > > >>> > > >>> Reconsider a Mantis. If you set the IPD knob to match your anatomy, they are > > >>> comfortable and the view is stunning. And you don't have to hunch over like you > > >>> do with a visor. > > >>> > > >> I don't have space for a Mantis here, mostly because I sometimes have > > >> very large prototypes on the lab bench. There can't be anything big and > > >> heavy in the way. When I want to avoid the hunch I use a Veho 20x USB > > >> microscope. A Supereyes 500x if it gets really small but that one > > >> doesn't allow several inches of vertical work space. Those are cheap > > >> "toy scopes" but they work quite well. As I said before, the good old > > >> days are today. > > > > > > My bench isn't very big either. My Mantis doesn't take much room. It > > > tucks away when I'm not using it. And it can swing over/into pretty > > > big rackmount boxes. > > > > > > https://dl.dropboxusercontent.com/u/53724080/Mantis/Mantis_Box.JPG > > > > > > > That's too big for me. My main lab bench is a large angled bench where > > one wing has a big equipment rack and the other needs to remain free > > from three side. It is a very heavy duty bench that can (and sometimes > > has to) take loads where the one in your picture would probably get bent > > in the frame or where it would snap the wood. >
something like this? http://www.inline.com.au/images/1252551884_Ceiling-Mount_3142.jpg -Lasse