Basic Info  
Pull Test  
Die attach  

UK Wedge Bonding Forum 1_2015
UK Wedge Bonding Forum 2_2015
Detector Mechanics Workshop 2012
Bond Workshop 2003

Recommendations for the design of hybrids (from the bonder's perspective) : - Design and layout considerations -

The bond surface

The main criteria from the perspective of bonding:

The material and its structure are compatible with the available method of bonding. In the case of the Bondlab, the method used is Aluminium Wedge Bonding.

The bond surface should be clean and free from all contaminants. Contamination sources are many and varied, from the obvious such as a fingerprint to the more subtle and less obvious.

The bond surface should be flat and of a consistent thickness and quality with no surface damage or irregularities.

The bond surface metal should be of a comparable hardness to the bond wire used.

The bond surface metal is bondable. This can be tested using the bond pull test.

Shape and Size of Bond Pads

This aspect of bonding is very much dependant upon the method of bonding that is foreseen, Aluminium wedge bonds need a more rectangular bond pad form whereas gold ball bonds favour a more square form pad.
It is not to say a wedge bond cannot be bonded on a square pad, but one must keep in mind the pad size with respect to the size and form of the bondfoot in three dimensions.
From a Hybrid point of view it is prudent to make the bond pad as large as is realistically possible. This allows a greater flexibility with respect to placement of the bond, placement of the die and fiducial to bond pad repeatable registration.

Pitch and Placement of Bond Pads

A bond pitch of 60µm is possible with 25µm wire, but the loop will be limited in height due to the nature of the Double Side Relief Tool which is necessary for fine pitch Aluminum wedge bonding.

                         Double side relief tool                ... another view

The thermal stress effects on the first bond heel by the loop should also be considered when making this choice.
The minimum preferable in line distance between two bonds is 300µm, this is tool dependant and to a certain extent loop dependant.

Bondhead Height Tolerances

Severe complications can result from electronic components (like LEMO connectors) positioned too close to bond pads. Bonding clearance around the tool of the 6400 is shown on this page.
The geometry of the bond head (tool, clamp, wire feed tube, transducer etc., see below) poses restrictions on the height of electrical components or any other objects in the vicinity of the bond pads (side view, 3D view) made by Antoine Guipet).

Other Aspects:

Backside of Hybrid / Pcb
Shape and size of bond pads
Pitch and layout of bond pads
Passivation of PCB / dies
Distance to high components


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