Smart Wire - Automatic Wiring

Once the die has been placed into the package it must be wirebonded.

There are two separate approaches to wirebonding - a rule based approach and a connection list approach. Depending on the nature of your data, one or the other will be preferred.

    Rule Based - the user defines a series of rules such as: All Die Pads with Net GND go to Ring GND. To follow this rule the program examines the net property of each die pad, and if the net property is equal to GND then it attempts to wirebond to a ring with name GND.

    Connection List - in many cases the user knows exactly which die pad goes to which package finger. A table is created with the die pad in column 1 and the finger number in column 2 and the program reads this to drive the wirebonding.

In actual operation a connection list is treated by the program as merely a long list of rules i.e. if the first line of the connection list has 1   5 in it, then it could be converted to a rule: die pad with number 1 goes to finger with number 5.

Wirebonding Setup

Prior to defining the rules and running them, the user must first set up the basic wirebonding parameters. This is done from the setup tab.

pads and rings tabs for setting up wirebonding parameters

In this dialog you define which layers your die pads lie on, which layer your fingers lie on and which layers represent ring or paddles for downbonding. You also define the wire diameter and how far apart wires will be spaced when multiple wires are placed on a single finger. Once all the basics are set, you move over to the Connection Rules tab



Rule Based Wiring

A series of "rules" can be defined that drive the wirebonding. The program attempts to follow these rules. Rules can be based on: tier to tier bonding, net to net bonding, pin number to pin bonding, net to ring bonding.

For example, the simplest rule would be merely to bond all die pads on the left side of the die to fingers on the left side of the package (repeat for top, bottom and right side)

simple tier based rules

Assuming your die pads have nets associated with them, you might want all die pads with net name VSS downbonded to the "paddle" (a layer on the package we created). In this case you might apply the following rule prior to the tier based rules.

You would make sure this rule was "first" so that these were not bonded to fingers using the other rule.

simple tier based rules


Connection List Wiring

For many leadframe applications the package designer has put together a table that maps each die pad to the desired package pin (or to the paddle). We call this a connection list. Details on on this page ....



 Page Topic
  1  Overview of Wirebond
  2  Importing GDSII
  3  Die Pad Recognition and Numbering
  4  Placing the Die
  5  Smart Wire
  6  How Downbonds are Handled
 
 Page Topic
  7  Wire Connection List
  8  Wire DRC
  9  Sorting Wires by Tiers
  10  Auto Documentation
  11  Title Border Template
  12  Filling Out the Title Border




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