Bonding, Handling, and Mounting Procedures for

Chip Diode Devices

M/A-COM Products

Rev. V3

Application Note

M541

7

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Acceptable Bonds

Wire or strap does not separate when tested.

No fractures in bond.

No separation of metallization.

Wire breaks before bonds

Bad Bonds

Wire separates from bond.

Bond fractures at weld

Separation of metallization

Bond Strength Pull Test

It is extremely important to maintain good quality control

procedures in order to ensure good bonding. The follow-

ing figures and tables illustrate criteria for visual inspec-

tion and for testing of bond strength.

Bonding to Small Mesas

When bonding to a small mesa type diode, it is sug-

gested to always use a strap. The strap, in many cases,

may be larger than the top of the mesa (the larger the

cross section area of the strap, the lower the parasitic

inductance). In the case, it is advisable to bond all or as

much to the entire top of the mesa as possible.

Good Bonding Criteria

When testing a mesa diode, if the bond is good, the

mesa will usually break off before the bond or strap

breaks. For all other bonds, the bonds should be as

strong as the wire or strap when tested by pulling. Im-

proper top bonding usually results in one of the following

problems:

Cracking or stressing the die through excessive pres-

sure.

Weak bonds from inadequate cleanliness or

improper

bonding conditions.

Excessive parasitic capacitance from overlapping wire or

strap.