Surface Mounting Guide
MLC Chip Capacitors
General
APPLICATION NOTES
Surface mounting chip multilayer ceramic capacitors
are designed for soldering to printed circuit boards or other
substrates. The construction of the components is such that
they will withstand the time/temperature profiles used in both
wave and reflow soldering methods.
Storage
Good solderability is maintained for at least twelve months,
provided the components are stored in their “as received”
packaging at less than 40°C and 70% RH.
Solderability
Handling
Terminations to be well soldered after immersion in a 60/40
tin/lead solder bath at 235 5°C for 2 1 seconds.
Chip multilayer ceramic capacitors should be handled with
care to avoid damage or contamination from perspiration
and skin oils. The use of tweezers or vacuum pick ups
is strongly recommended for individual components. Bulk
handling should ensure that abrasion and mechanical shock
are minimized. Taped and reeled components provides the
ideal medium for direct presentation to the placement
machine. Any mechanical shock should be minimized during
handling chip multilayer ceramic capacitors.
Leaching
Terminations will resist leaching for at least the immersion
times and conditions shown below.
Solder
Tin/Lead/Silver Temp. °C
60/40/0 260 5
Solder
Immersion Time
Seconds
Termination Type
Nickel Barrier
30 1
Preheat
It is important to avoid the possibility of thermal shock during
soldering and carefully controlled preheat is therefore
required. The rate of preheat should not exceed 4°C/second
and a target figure 2°C/second is recommended. Although
an 80°C to 120°C temperature differential is preferred,
recent developments allow a temperature differential
between the component surface and the soldering temper-
ature of 150°C (Maximum) for capacitors of 1210 size and
below with a maximum thickness of 1.25mm. The user is
cautioned that the risk of thermal shock increases as chip
size or temperature differential increases.
Recommended Soldering Profiles
Reflow
300
Natural
Cooling
Preheat
250
200
220°C
150
100
50
to
250°C
Soldering
Mildly activated rosin fluxes are preferred. The minimum
amount of solder to give a good joint should be used.
Excessive solder can lead to damage from the stresses
caused by the difference in coefficients of expansion
between solder, chip and substrate. AVX terminations are
suitable for all wave and reflow soldering systems. If hand
soldering cannot be avoided, the preferred technique is the
utilization of hot air soldering tools.
0
1min
(Minimize soldering time)
10 sec. max
1min
Wave
Cooling
Natural cooling in air is preferred, as this minimizes stresses
within the soldered joint. When forced air cooling is used,
cooling rate should not exceed 4°C/second. Quenching
is not recommended but if used, maximum temperature
differentials should be observed according to the preheat
conditions above.
300
Preheat
Natural
Cooling
250
200
150
100
50
T
230°C
to
Cleaning
250°C
Flux residues may be hygroscopic or acidic and must be
removed. AVX MLC capacitors are acceptable for use with
all of the solvents described in the specifications MIL-STD-
202 and EIA-RS-198. Alcohol based solvents are acceptable
and properly controlled water cleaning systems are also
acceptable. Many other solvents have been proven successful,
and most solvents that are acceptable to other components
on circuit assemblies are equally acceptable for use with
ceramic capacitors.
0
1 to 2 min
3 sec. max
(Preheat chips before soldering)
T/maximum 150°C
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