dm00048151

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Application note
EnFilm™ micro battery EFL700A39
recommendations for manual assembly on PCB
Introduction
This document provides recommendations to manually mount EnFilmTM micro battery
EFL700A39 on printed circuit board (PCB) for prototyping purposes (mount 1 to 6 micro
batteries to assemble in one step on PCB).
This prototype mounting process is intended for use at room temperature (glue
polymerization has to be done at room temperature).
STMicroelectronics has developed micro battery packaging with reduced thickness and
weight.
Micro battery package overview
En
Fil
m
EF
L7
700 00A
µA 39
h/3
V9
Figure 1.
®
- anode
+ cathode
March 2012
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PCB design recommendations
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PCB design recommendations
For optimum electrical performance and highly reliable solder joints, STMicroelectronics
recommends the PCB design guidelines listed in Table 1.
Note:
A too thick gold layer finishing on the PCB pad is not recommended (low joint reliability).
1.1
Micro vias
An alternative to routing on the top surface is to route on buried layers. To achieve this, the
pads are connected to the lower layers using micro vias.
.
Table 1.
PCB design recommendations
PCB pad design
Micros vias under pad are not allowed
PCB pad size (NSMD design)
Same pad size as micro battery (see Figure 2)
Solder mask opening (SMD design)
Same pad size as micro battery (see Figure 2)
PCB pad finishing
Cu-Ni (2-6µm max) or Cu OSP (organic substrate
protection)
Figure 2.
Contact dimensions
R 0.75
5.46
4.21
0.25
Pink colour:
contact pad Pt
5.46
4.21
0.25
25.4
3.45
5.46
R 0.75
3.71
R 0.75
5.46
25.4
Dimensions in mm
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Conductive glue assembly recommendations
Conductive glue assembly recommendations
Circuit Works® Conductive epoxy CW 2400.
Suppliers: Radio Spares n° 496265 or Farnell n° 604057.
3
Mounting procedure
1.
Read conductive epoxy MSDS carefully prior to use.
2.
Use surgical gloves and goggles.
3.
Clean surface to be contacted with cotton bud soaked with isopropyl alcohol (IPA).
Figure 3.
Clean contact surface
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Mounting procedure
4.
Mix equal amounts (1:1) by volume of 2 dots 4 mm diameter only. Mix thoroughly for at
least 2 minutes with plastic stick supplied with Conductive epoxy CW 2400.
Figure 4.
5.
Dot sizing
Apply a small quantity, 1mm diameter dot, on each contact of PCB maximum 12 dots.
Glue pot life is 10 minutes at 24 °C (75°F).
Figure 5.
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Application of 1mm dot glue
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Mounting procedure
6.
Flip the micro battery.
Figure 6.
7.
Placement of the micro battery
Put a weight of 30 g (for example a nut M16 mm) on the micro battery.
Figure 7.
Place a weight on the micro battery
Room temperature curing can be achieved in 4 hours at or above 24 °C (75°F). Do not use
temperature higher than room temperature to accelerate curing.
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Underfilling
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Underfilling
Underfilling is not needed.
5
Manual rework
The conductive glue doesn’t allow micro battery assembly rework.
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Gauge for glue dot dimension optimization
Appendix A
Gauge for glue dot dimension optimization
Print paper and laminate it with plastic coating.
Figure 8.
Gauge for glue dot dimension optimization
DOT TEST
4 mm
1 mm
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Revision history
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Revision history
Table 2.
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Document revision history
Date
Revision
15-Mar-2012
1
Changes
Initial release.
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