ST AN4046 Application note
AN4046
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.
Figure 1. Micro battery package overview
EnFilm
®
EFL700A39
700µAh/3V9
- anode
+ cathode
March 2012 Doc ID 022792 Rev 1 1/9
www.st.com
PCB design recommendations AN4046
1 PCB design recommendations
For optimum electrical performance and highly reliable solder joints, STMicroelectronics
recommends the PCB design guidelines listed in Tab l e 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
Figure 2. Contact dimensions
R 0.75
4.21
0.25
3.45
R 0.75
4.21
3.71
Cu-Ni (2-6µm max) or Cu OSP (organic substrate
protection)
0.25
5.46
25.4
5.46
R 0.75
Dimensions in mm
5.46
5.46
Pink colour:
contact pad Pt
25.4
2/9 Doc ID 022792 Rev 1
AN4046 Conductive glue assembly recommendations
2 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
Doc ID 022792 Rev 1 3/9
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