VXR-5000
Replacing Chip Components
Chip
components
are installed at the fac-
tory
by
a series of robots. The first one places
a spot of
adhesive
resi:tl
at
the
location where
each
part
is to
b-=
installed,
and
later robots
handle
and
place
parts
using
vacuum
suc-
tion.
For single-sided
boards,
solder
paste is ap-
plied to the
board
is t
hen
baked
to
harden
the
resin
and
flow
the
so
lde
r.
For d
ou
ble-sided
boards,
no
solder
paste
is applied,
but
the
board is
baked
(or
exposed
to
UV light) to
cure the resin before dip-solderin
g.
In
our
laboratories
and
service
sh
op
s,
small
quantities
of
c
hip
components
ar
e
mounted
manually
by
applying
a
spo
t of
resin, placing
with
tweezers,
and
then
solder-
ing
by
very small
dual
s
tr
eams
of
hot
air
(without
physica
l contact d
urin
g solderin
g).
We
remove
the
parts
by
first removing solder
using a
vacuum
suction iron,
whi
ch applies a
light, steady v
acu
um
at
the
iron tip,
and
then
breaking the adhesive with
twe
ezer
s.
The special
vacuum
sol
der
ing/
de-solder-
ing
equipment
is r
ecommen
de
d if y
ou
expect
to
do
a lot of chip replaceme
nt
s. Otherwise, it
is
usually possible to
remo
ve
and
replace chip
ccmponents
wit
h
on
ly a tapered, temp
er
a-
ture controlled solde
rin
g iron, a set of tweez-
ers
and
braided
copper
solder
wick.
Solder
ing
iron
temperatu
re should
be
below
280°C (536°F
).
5-2
Precautions
for
Chip Repla
ce
ment
K Do
not
disconnect a chip forcefully,
or
tne
foil
pattern
may
peel off
the
board.
K
Ne
ver re-use a chip
component.
Dispose
of all
removed
chip
components
immedi-
ately to avo
id
mix
ing
with
new
parts.
K Li
mi
t s
olderin
g time to 3 seconc.s
oL'
less to
av
oi
d
damaging
the
com
p
cnent
and
board.
Removing Chip Components
o Remove the solder
at
each
joint,
one
joint
at a time, using solder
wick
wetted
with
non-acidic flux as s
ho
wn
below. A
void
ap-
plying press
ur
e,
and
do
not
atte
mpt
to re-
move
th
e tinning from
the
chip's
electrode.
o Grasp the chip
on
both
si
de
s
with
tweez-
ers,
and
gen
tly twist t
he
tweezers back
and
fo
rth (to break
th
e
adhesive
bond)
wh
ile
alternately
he
ati
ng
each
electrode. Be care-
ful to avoid
pee
ling the foil traces from
the
bo
ard
. Dis
po
se
of
th
e chip w
hen
remov
ed.
o After removing
the
chip,
use
the
copper
braid
and
soldering iron to wick
away
any
excess solder
and
smooth
the
land
for in-
stallation of
the
replacement
part.
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