Surface Mount
Chip Capacitors
X7R
Polymer Termination
- a lead free termination
in ceramic devices that may not always be evident during the board
assembly process. Sometimes it may be the end customer who
finds out - when equipment fails!
Capacitor Body and Electrodes
Termination
MLCC’s are widely used in electronic circuit design for a multitude of
applications. Their small package size, technical performance and
suitability for automated assembly makes them the component of
choice for the specifier.
However, despite the technical benefits, ceramic components are brittle
and need careful handling on the production floor. In some
circumstances they may be prone to mechanical stress damage if not
used in an appropriate manner. Board flexing, depanelisation,
mounting through hole components, poor storage and automatic
testing may all result in cracking.
Careful process control is important at all stages of circuit board
assembly and transportation - from component placement to test and
packaging. Any significant board flexing may result in stress fractures
Solder Fillet
Force
Crack Initiation
Substrate
Fig 1. Typical Mechanical Crack
Ca
pa
cit
03
06
05
08
10
12
08
18
06
12
10pF
12
15
18
22
27
33
39
47
56
68
82
100pF
120
150
180
220
270
330
390
470
560
680
820
1.0nF
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
10
12
15
18
22
27
33
39
47
56
68
82
100
120
150
180
220
270
330
390
470
560
680
820
1.0µF
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
10
12
15
an
ce
500V
630V
1KV
2KV
500V
500V
1KV
2KV
630V
250V
500V
630V
1KV
2KV
3KV
200V
200V
200V
250V
250V
50/63V
100V
250V
50/63V
25V
25V
100V
16V
16V
100V
16V
25V
50/63V
200V
250V
50/63V
100V
25V
16V
X7R
28
Surface Mount
Chip Capacitors
X7R
With traditional termination materials and assembly, the chain of
materials from bare PCB to soldered termination, provides no
flexibility. In circumstances where excessive stress is applied - the
weakest link fails. This means the ceramic itself, which may fail
short circuit.
Fired ceramic
dielectric
Syfer has the solution -
FlexiCap
TM
has been developed as a result of listening to customers’
experiences of stress damage to MLCC’s from many manufacturers,
often caused by variations in production processes.
Our answer is a proprietary flexible epoxy polymer termination
material, that is applied to the device under the usual nickel barrier
finish. FlexiCap
TM
will accommodate a greater degree of board
bending than conventional capacitors.
Tin outer
layer
Intermediate
nickel layer
TM
FlexiCap
TM
termination
base
Metal
electrodes
Fig 2. FlexiCap MLCC cross section
12
18
500V
630V
1KV
2KV
3KV
50/63V
100V
20
22
630V
1KV
2KV
3KV
500V
25
22
500V
630V
1KV
3KV
2KV
500V
630V
X7R
2KV
3KV
1KV
4KV
50/63V
100V
200V
25V
250V
16V
25V
50/63V
100V
200V
250V
16V
40
36
10pF
12
15
18
22
27
33
39
47
56
68
82
100pF
120
150
180
220
270
330
390
470
560
680
820
1.0nF
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
10
12
15
18
22
27
33
39
47
56
68
82
100
120
150
180
220
270
330
390
470
560
680
820
1.0µF
1.2
1.5
1.8
2.2
2.7
3.3
3.9
4.7
5.6
6.8
8.2
10
12
15
25V
200V
notes
16V
250V
Shown above are standard and high voltage ranges of X7R chip capacitors
which are available with FlexiCap
TM
terminations. Please refer to our sales
office if you require other products in our range with this new termination.
For all other mechanical and electrical details please refer to the relevant
sections of this catalogue.
For ordering information see page 30.
29
Surface Mount
Chip Capacitors
Application Notes
benefits
The benefit to the user is to facilitate a wider process window -
giving a greater safety margin and substantially reducing the typical
root causes of mechanical stress cracking.
FlexiCap
TM
may be soldered using your traditional wave or reflow
solder techniques and needs no adjustment to equipment or current
processes.
Syfer has delivered millions of FlexiCap
TM
components and during
that time has collected substantial test and reliability data, working
in partnership with customers world wide, to eliminate mechanical
cracking.
Summary of PCB bend test results
The bend tests conducted have proved that the FlexiCap
TM
termination withstands a greater level of mechanical stress before
mechanical cracking occurs.
Typical examples:
Product
Mean bend
(mm)
Standard Term.
1.6
3.6
3.4
3.2
3.2
Mean bend
(mm)
FlexiCap
TM
6.4
6.3
6.4
6.0
6.1
Improvement
with
FlexiCap
TM
+ 400%
+ 75%
+ 88%
+ 88%
+ 91%
0603 X7R
0805 X7R
1206 X7R
1812 X7R
2220 X7R
Application Notes
FlexiCap
TM
may be handled, stored and transported in the same
manner as standard terminated capacitors. The requirements for
mounting and soldering FlexiCap
TM
are the same as for standard
SMD capacitors.
For customers currently using standard terminated capacitors there
should be no requirement to change the assembly process when
converting to FlexiCap
TM
.
Based upon board bend tests in accordance with IEC 60384-1 the
amount of board bending required to mechanically crack a polymer
terminated capacitor is significantly increased compared with
standard terminated capacitors.
It must be stressed however, that capacitor users must not assume
that the use of FlexiCap
TM
terminated capacitors will totally eliminate
mechanical cracking. Good process controls are still required for this
objective to be achieved.
●
Picture taken at 1,000x magnification using a SEM to demonstrate the fibrous
nature of the FlexiCap
TM
termination that absorbs increased levels of mechanical
stress.
Ordering Information
0805
Type No
Chip Size
Y
Termination
Y = FlexiCap
TM
100
Voltage
016 =16V
025 =25V
050 = 50V
063 = 63V
100 = 100V
200 = 200V
250 = 250V
500 = 500V
630 = 630V
1K0 =1kV
2K0 =2kV
3K0 =3kV
4K0 =4kV
5K0 =5kV
0101
Capacitance
First digit - 0
Second digit - First significant
figure of
capacitance value
Third digit - Second significant
figure of
capacitance value
Fourth digit - Number of zeros
following.
For values that do not fit the
model above, insert the
capacitance code letter for the
decimal point
e.g. 13N6 = 13.6nF
J
Tolerance
Stable class
J = ±5%
K = ±10%
M = ±20%
X
Dielectric
X = X7R
T
Packaging
T =178mm
(7”) reel
R =330mm
(13”) reel
B =Bulk pack
tubs
Suffix Code
Used for
specific
customer
requirements
© Copyright/Design right, Syfer Technology Limited, 2003.
FlexiCap
TM
is a registered trade mark of Syfer Technology Limited.
1. For details of the FlexiCap™ range see pages 28/29.
30
notes
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