>
> Jerry Avins <jya@ieee.org> wrote in news:3F0AE1B4.9614B6F5@ieee.org:
>
> > Kenneth Porter wrote:
> >>
> >> Jerry Avins <jya@ieee.org> wrote in news:3F03A9C0.8C7949FA@ieee.org:
> >>
> >> > I use a binocular erect-image microscope with about 2.5" clearance.
> >> > I bought the body on eBay for about $40, refurbished it and mounted
> >> > it, using an old 1.25" eyepiece focuser meant for a Newtonian
> >> > telescope. A pair of 10X WF about doubled the cost. It's also great
> >> > for removing splinters.
> >>
> >> Which of course points to the other common practice of fine hand work
> >> under a microscope: Surgery. Which I'll leave to folk with steadier
> >> hands than mine!
> >>
> >> --
> >> Kenneth Porter
> >> http://www.sewingwitch.com/ken/
> >
> > A pair of 3X clip-on Gallilean telescopes is another gadget I use a
> > lot. It focuses about about 11 inches past my nose, much further than
> > a plain magnifier of the same power, so I can use it while silver
> > soldering. (I have a lightweight torch with a mouth bit that puts the
> > flame at the right spot, allowing me to use both hands on the work.
> > The whole get-up makes me look like a bug-eyed dragon.)
> >
> > Jerry
>
> Jerry, are these the eyeglass attachments that my dentist uses? He said
> they are expensive? What do they cost and where do you buy them? They
> look like they might work well for soldering 0805 parts, SO ICs etc. H
>
> --
> Al Clark
> Danville Signal Processing, Inc.
> --------------------------------------------------------------------
> Purveyors of Fine DSP Hardware and other Cool Stuff
> Available at http://www.danvillesignal.com
I got mine from Edmund Scientific years ago. Last I looked, they now
sell only monoculars, and I have one of those too for around $40. It
screws into a holder that is a pain. (With a Gallilean telescope, the
eye relief is negative, so the closer you get to it, the larger the
field of view.) I made a nut with the same thread as the holder, and one
of these days, I'll drill a cheap plastic lens and mount it. Doing it
twice requires a lot of cut and try to get the convergence right. Your
dentist's probably has optics not much better than what I've got. The
cost is in mounting them with equipment that can get it right most of
the time, and a surcharge to cover those times when it needs done over.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Al Clark●July 8, 20032003-07-08
Jerry Avins <jya@ieee.org> wrote in news:3F0AE1B4.9614B6F5@ieee.org:
> Kenneth Porter wrote:
>>
>> Jerry Avins <jya@ieee.org> wrote in news:3F03A9C0.8C7949FA@ieee.org:
>>
>> > I use a binocular erect-image microscope with about 2.5" clearance.
>> > I bought the body on eBay for about $40, refurbished it and mounted
>> > it, using an old 1.25" eyepiece focuser meant for a Newtonian
>> > telescope. A pair of 10X WF about doubled the cost. It's also great
>> > for removing splinters.
>>
>> Which of course points to the other common practice of fine hand work
>> under a microscope: Surgery. Which I'll leave to folk with steadier
>> hands than mine!
>>
>> --
>> Kenneth Porter
>> http://www.sewingwitch.com/ken/
>
> A pair of 3X clip-on Gallilean telescopes is another gadget I use a
> lot. It focuses about about 11 inches past my nose, much further than
> a plain magnifier of the same power, so I can use it while silver
> soldering. (I have a lightweight torch with a mouth bit that puts the
> flame at the right spot, allowing me to use both hands on the work.
> The whole get-up makes me look like a bug-eyed dragon.)
>
> Jerry
Jerry, are these the eyeglass attachments that my dentist uses? He said
they are expensive? What do they cost and where do you buy them? They
look like they might work well for soldering 0805 parts, SO ICs etc. H
--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com
Reply by Jerry Avins●July 8, 20032003-07-08
Kenneth Porter wrote:
>
> Jerry Avins <jya@ieee.org> wrote in news:3F03A9C0.8C7949FA@ieee.org:
>
> > I use a binocular erect-image microscope with about 2.5" clearance. I
> > bought the body on eBay for about $40, refurbished it and mounted it,
> > using an old 1.25" eyepiece focuser meant for a Newtonian telescope. A
> > pair of 10X WF about doubled the cost. It's also great for removing
> > splinters.
>
> Which of course points to the other common practice of fine hand work under
> a microscope: Surgery. Which I'll leave to folk with steadier hands than
> mine!
>
> --
> Kenneth Porter
> http://www.sewingwitch.com/ken/
A pair of 3X clip-on Gallilean telescopes is another gadget I use a lot.
It focuses about about 11 inches past my nose, much further than a plain
magnifier of the same power, so I can use it while silver soldering. (I
have a lightweight torch with a mouth bit that puts the flame at the
right spot, allowing me to use both hands on the work. The whole get-up
makes me look like a bug-eyed dragon.)
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Kenneth Porter●July 8, 20032003-07-08
Al Clark <dsp@danvillesignal.com> wrote in
news:Xns93AC5F400B1DFaclarkdanvillesignal@66.133.130.30:
> BGAs are certainly a reality and if you want to build DSP boards you
> better get used to them. Of course, there are suppliers that would love
> to save you the trouble ;-)
For those lurkers who don't know, Al's company makes nice little PCB's with
the BGA DSP pre-mounted along with memory and other support stuff, and the
signals brought out to convenient connectors. The boards are still very
compact and the pricing was quite reasonable for incorporation in products
with small runs.
This actually wasn't the first time I saw this kind of product. I'd been
evaluating the PowerPC at one point and there's a German company making
similar boards with Motorola high-integration BGA PPC's. Their approach is
to standardize the connectors and sell various combinations of processor
boards and I/O boards to plug them into.
--
Kenneth Porter
http://www.sewingwitch.com/ken/
Reply by Kenneth Porter●July 8, 20032003-07-08
Jerry Avins <jya@ieee.org> wrote in news:3F03A9C0.8C7949FA@ieee.org:
> I use a binocular erect-image microscope with about 2.5" clearance. I
> bought the body on eBay for about $40, refurbished it and mounted it,
> using an old 1.25" eyepiece focuser meant for a Newtonian telescope. A
> pair of 10X WF about doubled the cost. It's also great for removing
> splinters.
Which of course points to the other common practice of fine hand work under
a microscope: Surgery. Which I'll leave to folk with steadier hands than
mine!
--
Kenneth Porter
http://www.sewingwitch.com/ken/
Reply by Eric Jacobsen●July 4, 20032003-07-04
On Wed, 02 Jul 2003 23:33:58 -0400, Jerry Avins <jya@ieee.org> wrote:
>Steve Underwood wrote:
>>
>> Al Clark wrote:
>> > Steve Underwood <steveu@dis.org> wrote in
>> > news:bduvmg$pm1$1@hfc.pacific.net.hk:
>> >
>> >>Al Clark wrote:
>> >
>> > Where did cleaning come in? Reballing is a process that remakes the BGA
>> > contacts.
>> >
>> > Profiling determines how fast the board heats, etc. for correct reflow.
>> > You only do it once for a given assembly type. If you did 6 identical
>> > boards you wou profile one and place 6 (cost = $80 + 6*$65)
>>
>> OK, a confusion of terms. I understand what you mean by profiling now.
>>
>> > Unless you have parts on both sides of the board, parts are not glued.
>>
>> Are you refering to QFP or BGA? QFPs are routinely glued by the robots
>> so the board is less susceptible to shaking as it passes through (maybe)
>> several other robot and shakey conveyer belt steps. I wish people
>> wouldn't use that concrete like red glue, though. It makes changing QFPs
>> a real pain. Perhaps that is the intention!
>>
>> > When I hand solder a QFP, I place a small amount of solder on a corner
>> > pad. I then heat this pad with the QFP pins absolutely perfectly aligned
>> > on the board. I then flip the board 180 degrees, and solder the opposite
>> > corner. The rest of the pins are then soldered in a kind of controlled
>> > bridging approach. FLUX IS YOUR FRIEND!!!
>>
>> In production environments the girls (its usually girls) tend to use a
>> soldering iron with a bit the whole width of one side of the QFP. In 4
>> goes (i.e. one on each side) they can put a QFP in place very
>> accurately. Messing around with corner pins is just for people like us,
>> who don't do this often enough [actually one in a while is often enough
>> for me :-\ ]
>>
>> > My technician uses a x-acto knife to help slide the part, I use tweezers.
>> > In all cases, this is done under a microscope.
>>
>> I can't image being able to solder with a microscope. I can't remember
>> seeing someone try. Doesn't the lens get in the way? Even low power
>> microscopes come quite close to the object. Doesn't it fog with flux, too?
>>
>> > Its been a long time since I laid out pcbs on a light table with tape. I
>> > remember when plated thru holes were troublesome.
>> >
>> > Now even a "down & dirty" house can etch 5/5 multilayer boards (5 mil min
>> > trace, 5 mil clearance).
>>
>> They always seem to get them bubble free too. Most places used to give
>> you a few bubbles a few years ago.
>> >
>> >>>BGAs are certainly a reality and if you want to build DSP boards you
>> >>>better get used to them. Of course, there are suppliers that would
>> >>>love to save you the trouble ;-)
>> >>
>> >>If you want to build practically anything above the simple MCU level
>> >>you'd better get used to them.
>> >
>> > What's a DIP? This term seems vaguely familiar.....
>>
>> Cheese DIP? Lets go for a DIP? They seem familiar.....
>>
>> Regards,
>> Steve
>
>There are some pretty nice skinny DIPS around.
>
>Jerry
I used to have some PALs that were DIPs...
...actually think I still do...
;)
Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org
Reply by Jerry Avins●July 3, 20032003-07-03
Al Clark wrote:
>
...
>
> I use a microscope that has a range of 7x - 30x. The microscope is
> mounted on a boom stand. With a bit of practice you learn exactly where
> your hands are under the scope. There is a real incentive for learning
> this skill quickly since the tip of the soldering iron is maybe 700
> degrees F. Soldering is best done with the microscope set to 7-8x.
> Sometimes, I inspect the connections at 20-30x, especially if I have
> identified a problem.
>
> Clay is right that the focal length should be long. There are optical
> systems for this purpose aimed at electronics that are very nice, I use
> an old Baush & Lomb which is OK. My tech uses an Olympus that is better.
>
...
I use a binocular erect-image microscope with about 2.5" clearance. I
bought the body on eBay for about $40, refurbished it and mounted it,
using an old 1.25" eyepiece focuser meant for a Newtonian telescope. A
pair of 10X WF about doubled the cost. It's also great for removing
splinters. It has two powers, about 7.5 and 15. It's good enough.
jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Jerry Avins●July 3, 20032003-07-03
Steve Underwood wrote:
>
> Al Clark wrote:
> > Steve Underwood <steveu@dis.org> wrote in
> > news:bduvmg$pm1$1@hfc.pacific.net.hk:
> >
> >>Al Clark wrote:
> >
> > Where did cleaning come in? Reballing is a process that remakes the BGA
> > contacts.
> >
> > Profiling determines how fast the board heats, etc. for correct reflow.
> > You only do it once for a given assembly type. If you did 6 identical
> > boards you wou profile one and place 6 (cost = $80 + 6*$65)
>
> OK, a confusion of terms. I understand what you mean by profiling now.
>
> > Unless you have parts on both sides of the board, parts are not glued.
>
> Are you refering to QFP or BGA? QFPs are routinely glued by the robots
> so the board is less susceptible to shaking as it passes through (maybe)
> several other robot and shakey conveyer belt steps. I wish people
> wouldn't use that concrete like red glue, though. It makes changing QFPs
> a real pain. Perhaps that is the intention!
>
> > When I hand solder a QFP, I place a small amount of solder on a corner
> > pad. I then heat this pad with the QFP pins absolutely perfectly aligned
> > on the board. I then flip the board 180 degrees, and solder the opposite
> > corner. The rest of the pins are then soldered in a kind of controlled
> > bridging approach. FLUX IS YOUR FRIEND!!!
>
> In production environments the girls (its usually girls) tend to use a
> soldering iron with a bit the whole width of one side of the QFP. In 4
> goes (i.e. one on each side) they can put a QFP in place very
> accurately. Messing around with corner pins is just for people like us,
> who don't do this often enough [actually one in a while is often enough
> for me :-\ ]
>
> > My technician uses a x-acto knife to help slide the part, I use tweezers.
> > In all cases, this is done under a microscope.
>
> I can't image being able to solder with a microscope. I can't remember
> seeing someone try. Doesn't the lens get in the way? Even low power
> microscopes come quite close to the object. Doesn't it fog with flux, too?
>
> > Its been a long time since I laid out pcbs on a light table with tape. I
> > remember when plated thru holes were troublesome.
> >
> > Now even a "down & dirty" house can etch 5/5 multilayer boards (5 mil min
> > trace, 5 mil clearance).
>
> They always seem to get them bubble free too. Most places used to give
> you a few bubbles a few years ago.
> >
> >>>BGAs are certainly a reality and if you want to build DSP boards you
> >>>better get used to them. Of course, there are suppliers that would
> >>>love to save you the trouble ;-)
> >>
> >>If you want to build practically anything above the simple MCU level
> >>you'd better get used to them.
> >
> > What's a DIP? This term seems vaguely familiar.....
>
> Cheese DIP? Lets go for a DIP? They seem familiar.....
>
> Regards,
> Steve
There are some pretty nice skinny DIPS around.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Al Clark●July 3, 20032003-07-03
"Clay S. Turner" <physicsNOOOOSPPPPAMMMM@bellsouth.net> wrote in
news:T7MMa.5048$Sy1.78@fe02.atl2.webusenet.com:
>
> "Steve Underwood" <steveu@dis.org> wrote in message
> news:bdvu5a$nqq$1@hfc.pacific.net.hk...
>> I can't image being able to solder with a microscope. I can't
>> remember seeing someone try. Doesn't the lens get in the way? Even
>> low power microscopes come quite close to the object. Doesn't it fog
>> with flux, too?
>>
>
> Hello Steve,
>
> I have had the priviledge of soldering under a microscope. And I know
> quite a few others who do it that routinely with TQFPs. The trick is
> to use a scope with a very long focal length objective. This will give
> you several inches of working space. This trick has been exploited for
> years in macrophotography so as to have more working room. The 6x
> objective gives somthing like 4 or 5 inches of working room. The
> scope I used is set up so you look horizontally into the unit and your
> work is underneath the unit. This takes a little getting use to.
I use a microscope that has a range of 7x - 30x. The microscope is
mounted on a boom stand. With a bit of practice you learn exactly where
your hands are under the scope. There is a real incentive for learning
this skill quickly since the tip of the soldering iron is maybe 700
degrees F. Soldering is best done with the microscope set to 7-8x.
Sometimes, I inspect the connections at 20-30x, especially if I have
identified a problem.
Clay is right that the focal length should be long. There are optical
systems for this purpose aimed at electronics that are very nice, I use
an old Baush & Lomb which is OK. My tech uses an Olympus that is better.
>
> A few months back I was was at a client's where they do quite a bit of
> work with BGAs, and they had a neat optical camera that could see
> three rows of balls on a soldered BGA. The head of the camera was
> about a 1/4 inch wide and would be manouvered about by having the
> board on a translation table. Their production engineer showed me a
> bunch of stuff about their manufacturing capability, and I was duly
> impressed. I had done a BGA design for them, and they were building
> it. BGAs are not for the home assembling environment! I've heard many
> claims that BGA soldering has better reliability than TQFP soldering.
> Of course this assumes one possesses a full production type of setup.
>
> Clay
>
>
>
The house I use for BGAs have many years experience as a rework center
for Silicon Graphics. They have individual screen stencils for most BGAs
which is great for prototyping.
You can equip a bench for 1-2K dollars (or euros) to solder most SMT
parts. BGAs are SUBSTANTIALLY more expensive. I can't see ever having our
own equipment for this purpose.
--
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com
Reply by Clay S. Turner●July 2, 20032003-07-02
"Steve Underwood" <steveu@dis.org> wrote in message
news:bdvu5a$nqq$1@hfc.pacific.net.hk...
> I can't image being able to solder with a microscope. I can't remember
> seeing someone try. Doesn't the lens get in the way? Even low power
> microscopes come quite close to the object. Doesn't it fog with flux, too?
>
Hello Steve,
I have had the priviledge of soldering under a microscope. And I know quite
a few others who do it that routinely with TQFPs. The trick is to use a
scope with a very long focal length objective. This will give you several
inches of working space. This trick has been exploited for years in
macrophotography so as to have more working room. The 6x objective gives
somthing like 4 or 5 inches of working room. The scope I used is set up so
you look horizontally into the unit and your work is underneath the unit.
This takes a little getting use to.
A few months back I was was at a client's where they do quite a bit of work
with BGAs, and they had a neat optical camera that could see three rows of
balls on a soldered BGA. The head of the camera was about a 1/4 inch wide
and would be manouvered about by having the board on a translation table.
Their production engineer showed me a bunch of stuff about their
manufacturing capability, and I was duly impressed. I had done a BGA design
for them, and they were building it. BGAs are not for the home assembling
environment! I've heard many claims that BGA soldering has better
reliability than TQFP soldering. Of course this assumes one possesses a full
production type of setup.
Clay