M02014 Datasheet, PDF (15/19 Pages) M/A-COM Technology Solutions, Inc. – CMOS Transimpedance Amplifier with AGC for Fiber Optic Networks up to 2.5 Gbps

Applications Information
4.4.1
Assembly
The M02014 is designed to work with a wirebond inductance of 1 nH ± 0.25 nH. Many existing TO-Can
configurations will not allow wirebond lengths that short, since the PIN diode submount and the TIA die are more
than 1 mm away in the vertical direction, due to the need to have the PIN diode in the correct focal plane. This can
be remedied by raising up the TIA die with a conductive metal shim. This will effectively reduce the bond wire
length. Refer to Figure 4-4 above for details.
Mindspeed recommends ball bonding with a 1 mil (25.4 µm) gold wire. For performance reasons the PINA pad is
smaller than the others and also has less via material connected to it. It therefore requires more care in setting of
the bonding parameters. For the same reason PINA has no ESD protection.
In addition, please refer to the Mindspeed Product Bulletin (document number 0201X-PBD-002). Care must be
taken when selecting chip capacitors, since they must have good low ESR characteristics up to 1.0 GHz. It is also
important that the termination materials of the capacitor be compatible with the attach method used.
For example, Tin/Lead (Pb/Sn) solder finish capacitors are incompatible with silver-filled epoxies. Palladium/Silver
(Pd/Ag) terminations are compatible with silver filled epoxies. Solder can be used only if the substrate thick-film
inks are compatible with Pb/Sn solders.
4.4.2
Recommended Assembly Procedures
For ESD protection the following steps are recommended for TO-Can assembly:
a. Ensure good humidity control in the environment (to help minimize ESD).
b. Consider using additional ionization of the air (also helps minimize ESD).
c. It is best to ensure that the body of the TO-can header or the ground lead of the header is grounded
through the wire-bonding fixture. The best solution will ensure that the V_CC lead of the TO-Can is also
grounded. When this is done and the procedure below is followed, the photodiode will help reduce the
impact to PINA of any positive charge on the wire bonder when bonding to PINA, which is the very last
bond placed. (Because the PD is already bonded to PINK and PINK has an internal ESD diode between
itself and V_CC, if V_CC is grounded, this will help protect PINA.)
d. The most reliable protection to prevent ESD damage on the die is to assure that the wirebonder (including
the spool, clamp, etc.) is properly grounded.
1. Wire bond the ground pad(s) of the die first.
2. Then wire bond the VCC pad to the TO-Can lead.
3. Then wire bond any other pads going to the TO-Can leads (such as DOUT, DOUT and possibly MON)
4. Next wire bond any capacitors inside the TO-Can.
5. Inside the TO-can, wire bond PINK.
6. The final step is to wire bond PINA.
02014-DSH-001-D
Mindspeed Technologies^®
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