M02011

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18

CMOS Transimpedance Amplifier with AGC

for Fiber Optic Networks up to 622 Mbps

Rev V5

4.6.1

Assembly

The M02011 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 for details.

MACOM 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 MACOM Product Bulletin (document number 0201x-PBD-002-A). 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.

4.6.2

Recommended Assembly Procedures

For ESD protection the following steps are recommended for TO-Can assembly:

•

Ensure good humidity control in the environment (to help minimize ESD).

•

Consider using additional ionization of the air (also helps minimize ESD).

•

As a minimum, 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 for the following steps. The wire bonder itself should also be

grounded.

1. Wire bond the ground pad(s) of the die first.

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.