icebear
16.03.2006, 18:54
Тема не новая, есть некоторая информация По BGA есть вот это:
http://www.lrr.in.tum.de/~acher/bga/
на немецком, если будет спрос, я могу перевести.
Второе, пролетало в comp.arch.fpga следующее:
"Contrary to others experience, I've done BGA parts pretty successfully
in "hobby mode", as well as with professional rework equipment. I've
developed a few "tricks" that help.
First, solder paste is very difficult to manage with hand placement.
Instead, use water soluable flux on the board pads, and push a large
solder ball over all the boards pads till you have a small shinny
solder mound on each pad with a fairly uniform size to attach the BGA
with. Clean the board well to remove the used flux, and apply fresh
flux to both the board and the BGA balls.
Second, position the BGA part on top of the pcb pads. It's very useful
at this point to have a silk screened outline of the package to center
the part with, that is very close to the real package size.
Third, carefully place in a preheated convection oven, and bake. The
correct time for this takes some practice and calibration of YOUR
setup. Visually verify that the balls have a uniform "squat" on all
four sides ... this generally means the parts wetted fine, and the part
settled down on the balls at reflow temp.
Read the lit about recommended profiles for various packages ... you
may not be able to exactly do those profiles, but you can come close
with some practice.
I've had pretty good luck using several different table top forced air
"convection ovens" with digital controls. These are fairly inexpensive,
and typically can regulate temps within 10 degrees F or so. Their
problem, is uneven air flow which may result in uneven board heating if
you do not give this some thought. Two of the ovens I used, required
setting the board on a soda can near the center of the oven, with the
turn table removed. A third oven required fashioning a foil air duct to
make sure the hot air flow evenly covered the board.
I suggest getting a non-contact IR thermometer with a spot capability
... these can be had fairly cheaply from a number of discount sources,
including Harbor frieght. Using a salvage pcb of similar size and mass
as your "test board" you can experiment with your "profile". I would
suggest starting with the oven preheated to about 10-25F higher than
your expected solder temp, quickly inserting your test board, and
letting it bake for 2-3 minutes, open the door and quickly read several
spots on the test board with the IR thermometer before the cool air
drops the temp too much. Let the test board cool back to room temp, and
repeat several times increasing the bake time about a minute each time.
When you find the point where the board just reaches the solder temp,
you can then program the oven to turn off 2 min after reaching that
temp, and slowly cool the board back down without thermal shocking the
BGA.
Another process, is to pickup some slavage BGA parts with a similar
package, and make a test board with the on die thermal diode brought
out to test points, so you can run the wires out the door and monitor
the die temp as you develop your thermal profile. You can also do this
with your own board and FPGA's. You can also epoxy attach several
thermal diodes to a test board, and monitor the profile in real time at
several points.
Pickup some Solderquik reballing preforms for the parts you plan to
use. That way you can clean off your mistakes, and reball the parts to
try again.
The one thing you do not want to do, is get the newer BGA's too hot, or
thermal shock them with cold air. Older parts in BG432 and BG560
packages are much more forgiving. I would suggest learning this
process with XC4K, Virtex, or Virtex-E parts in BG432/BG560 packages,
and once mastered move on to newer high density packages."
Это тут за меня переведут :)
И третье, что касается SMD воощбе, есть видеофайл (к сожалению текстовые комменты там на немецком, но их мало, как в немом кино прямо), где показано, как шаг за шагом припаять SMD деталь, т.е. xQFP.
Интерес по первому и по третьему пунтку есть. Видео кстати взял вот отсюда: http://www.ulrichradig.de/gfx/video/SMD_einloeten.wmv
http://www.lrr.in.tum.de/~acher/bga/
на немецком, если будет спрос, я могу перевести.
Второе, пролетало в comp.arch.fpga следующее:
"Contrary to others experience, I've done BGA parts pretty successfully
in "hobby mode", as well as with professional rework equipment. I've
developed a few "tricks" that help.
First, solder paste is very difficult to manage with hand placement.
Instead, use water soluable flux on the board pads, and push a large
solder ball over all the boards pads till you have a small shinny
solder mound on each pad with a fairly uniform size to attach the BGA
with. Clean the board well to remove the used flux, and apply fresh
flux to both the board and the BGA balls.
Second, position the BGA part on top of the pcb pads. It's very useful
at this point to have a silk screened outline of the package to center
the part with, that is very close to the real package size.
Third, carefully place in a preheated convection oven, and bake. The
correct time for this takes some practice and calibration of YOUR
setup. Visually verify that the balls have a uniform "squat" on all
four sides ... this generally means the parts wetted fine, and the part
settled down on the balls at reflow temp.
Read the lit about recommended profiles for various packages ... you
may not be able to exactly do those profiles, but you can come close
with some practice.
I've had pretty good luck using several different table top forced air
"convection ovens" with digital controls. These are fairly inexpensive,
and typically can regulate temps within 10 degrees F or so. Their
problem, is uneven air flow which may result in uneven board heating if
you do not give this some thought. Two of the ovens I used, required
setting the board on a soda can near the center of the oven, with the
turn table removed. A third oven required fashioning a foil air duct to
make sure the hot air flow evenly covered the board.
I suggest getting a non-contact IR thermometer with a spot capability
... these can be had fairly cheaply from a number of discount sources,
including Harbor frieght. Using a salvage pcb of similar size and mass
as your "test board" you can experiment with your "profile". I would
suggest starting with the oven preheated to about 10-25F higher than
your expected solder temp, quickly inserting your test board, and
letting it bake for 2-3 minutes, open the door and quickly read several
spots on the test board with the IR thermometer before the cool air
drops the temp too much. Let the test board cool back to room temp, and
repeat several times increasing the bake time about a minute each time.
When you find the point where the board just reaches the solder temp,
you can then program the oven to turn off 2 min after reaching that
temp, and slowly cool the board back down without thermal shocking the
BGA.
Another process, is to pickup some slavage BGA parts with a similar
package, and make a test board with the on die thermal diode brought
out to test points, so you can run the wires out the door and monitor
the die temp as you develop your thermal profile. You can also do this
with your own board and FPGA's. You can also epoxy attach several
thermal diodes to a test board, and monitor the profile in real time at
several points.
Pickup some Solderquik reballing preforms for the parts you plan to
use. That way you can clean off your mistakes, and reball the parts to
try again.
The one thing you do not want to do, is get the newer BGA's too hot, or
thermal shock them with cold air. Older parts in BG432 and BG560
packages are much more forgiving. I would suggest learning this
process with XC4K, Virtex, or Virtex-E parts in BG432/BG560 packages,
and once mastered move on to newer high density packages."
Это тут за меня переведут :)
И третье, что касается SMD воощбе, есть видеофайл (к сожалению текстовые комменты там на немецком, но их мало, как в немом кино прямо), где показано, как шаг за шагом припаять SMD деталь, т.е. xQFP.
Интерес по первому и по третьему пунтку есть. Видео кстати взял вот отсюда: http://www.ulrichradig.de/gfx/video/SMD_einloeten.wmv