中龙集团
Dragon Group China Limited
BIRD
®
(1) Mounting: The main purpose of mounting to make every BGA solder align to the
PCB pad with special equipment.
(2)Hot air reflow: Hot air reflow soldering is the key to the whole BGA Rework.
①
The curve of reflow soldering of BGA Rework should be similar with the original
soldering one. Hot air reflow soldering curve can be divided into four zones, including
preheat zone, heating zone, recirculation zone and cooling area. These four zones
’
temperature and time parameter can be set respectively, when it connects with the
computer, these programs can be saved and transferred at any moment.
②
In
reflow soldering
process, we must choose the right heating temperature and time of
different zones; at the same time, we should notice the heating speed. Commonly, the
maximal heating rate is not more than 6
℃
/s before 100
℃
, and the maximal heating rate is not
more than 3
℃
/s after 100
℃
. In the cooling zone, the maximal cooling rate is not more than 6
℃
/s, because both of the exorbitant heating rate and cooling rate may cause damage to PCB
and BGA, which sometimes cannot be observed by unaided eyes. For different BGA and
different
solder pastes
, we should choose different heating temperature and time. For
example,
reflux temperature
of CBGA BGA should be higher than that of PBGA
…
choose
the higher
reflux temperature
. For
no clean solder paste
, its
activity
is lower than non-
no
clean solder paste
, so the soldering temperature should not be too high, and the soldering
time should not be too long, so as to prevent the oxidation of solder
particle
.
③
In hot air reflow soldering, the bottom of PCB board should be heated. There are two
purposes for this kind of heating. First, avoid the warping and deformation in one-side
heated PCB board; second, shorten the time of the solder paste melting. For the
dimension pad of BGA rework, this kind of heating on the bottom of PCB is especially
important. There are two ways of heating on the bottom of BGA rework equipment. One
of them is hot air heating, and the other is infrared ray heating. The advantage of hot air
heating is the homogeneous heating, which common Rework Techniques suggest to adopt
this way of heating. What opposite with it is the disadvantage of infrared ray
’
s
inhomogeneous heating.
④
We should choose the right hot air reflux suction nozzle. The hot air reflux nozzle is
non-contact heating, which depend on the high temperature air current make every solder
of joint on BGA melt synchronously. For that reason, it ensures the steady temperature
circumstance in the whole of reflux process, and it protects the adjacent parts from
damaging by the convective hot air
’
s regeneration.
B.
Installation
1. Place
In order to ensure the validity of BGA Rework Station, the installation should meet the
following requirements.
a. Away from inflammable and explosives;
Summary of Contents for Bird AC-5K
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