How to implement Chip on Board (CoB) technology by using Allegro PCB Editor

CoB refers to the technology process where a bare die is mounted and electrically connected to a Printed Circuit Board (PCB). Typically, it is encapsulated with a silicone- or epoxy-based material (glob) in the PCB. This has the capability to support both wirebond and flip-chip die attachment methods across various substrate types like laminate, ceramic, and so on.  

Some advantages of COB are: 

• The bare die is directly attached to the PCB and hence, there is no packaging requirements. 
• Quick die replacement  
• Better thermal characteristics 

Allegro PCB Editor supports basic wirebond applications. 

After placing the bare die on the board, you can add, edit, and set the wirebond settings.  

A 3D view of a CoB is shown below:

Basic steps to build a  die symbol and add wirebonds from the die to the PCB by using the wirebond functionality in Allegro PCB Editor are: 

1. Create wirebond die symbol in the Allegro Symbol Editor.  
2. Place wirebond die in the Allegro PCB Layout Editor using Place > Manually. 
3. Add wirebonds.  

Set the application mode in Allegro PCB Editor to “Wire Bond Edit”, right mouse click over Die Pin and select “Add Wire Bond” to start adding the wire bonds. Left mouse click on the canvas will place the bondfingers. 

If required, move wirebond tack point. 

Make sure you turn on the visibility for Bond wire profiles >Top and Conductor > Bond_Top from Display > Color/Visibility.  

To know how to build a die symbol and add wirebonds from the die to the PCB by using the wirebond functionality in Allegro PCB Editor, click here.