Package Substrate Wire Bonding Pads High Density Wiring

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Solution Overview

Problem

Current methods for forming wire bonding metal layers on package substrates face challenges in achieving high density wiring, fine spacing between wire bonding pads, and enhancing bonding capability, particularly for high-pin-count applications, due to limitations in electroplating and chemical deposition processes.

Innovation Solution

A package substrate with a chemical plating metal layer of nickel/gold or nickel/palladium/gold on wire bonding pads, followed by a gold wire bonding metal layer formed through electroplating, eliminating the need for plating lines and ensuring a thicker, firmer gold layer for improved bonding capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If electroplating via plating lines is used to form wire bonding metal layer, then the metal layer can be formed on wire bonding pads, but a great deal of area of the substrate body is taken, thereby being unable to reach objectives of high density wiring and fine spacing between wire bonding pads

Engineering Contradiction:

Improvespacing between wire bonding padsVSAvoidarea occupied by plating lines

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent extracts and removes the plating lines from the substrate structure, forming the wire bonding metal layer directly on the wire bonding pads without requiring separate plating line structures. This eliminates the area occupation by plating lines and enables fine spacing between wire bonding pads for high density wiring

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary electroplating of the wire bonding pads with a metal layer (such as copper or nickel) before the wire bonding process. This preliminary action prepares the pads with adequate metal thickness and bonding surface area, eliminating the need for subsequent plating lines while ensuring sufficient bonding capability

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If chemical deposition is used to form wire bonding metal layer, then the layer can be formed on wire bonding pads, but sufficient thickness costs highly and the layer has softer texture with poor bonding capability

Engineering Contradiction:

Improvethickness of wire bonding metal layerVSAvoidbonding capability with wire

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces chemical deposition with electroplating to form the wire bonding metal layer. Electroplating provides better control over layer thickness, produces a harder and more durable metal layer, and significantly improves bonding capability with wire while being more cost-effective for achieving sufficient thickness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the deposition method parameter from chemical deposition to electroplating, which fundamentally alters the properties of the formed metal layer. Electroplating enables precise control of thickness parameters, produces a harder texture, and enhances bonding capability while reducing costs compared to chemical deposition

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables high density wiring, fine spacing between wire bonding pads, and enhanced bonding capability with wires, meeting the demands of high-pin-count applications while reducing fabrication complexity and costs.

Implementation Method 1

form a chemical plating metal layer 42 on the wire bonding pads 401 and the solder ball pads 402 respectively

Methodology Applied

Scientific EffectChemical deposition: Chemical Vapour Deposition

Implementation Method 2

form a wire bonding metal layer 45 on the chemical plating metal layer 42 of the wire bonding pads 401 by means of electroplating

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS7718470B2Package substrate and method for fabricating the same

Publication Date: 2010.05.18 PHOENIX PRECISION TECH CORP

AI summary

A package substrate and a method for fabricating the same are provided according to the present invention. The package substrate includes: a substrate body with a die attaching side and a ball implanting side lying opposite each other, having a plurality of wire bonding pads and a plurality of solder ball pads respectively, and having a first insulating passivation layer and a second insulating passivation layer respectively, wherein a plurality of first apertures and a plurality of second apertures are formed in the first insulating passivation layer and the second insulation passivation layer respectively to corresponding expose the wire bonding pads and the solder ball pads; a chemical plating metal layer formed on the wire bonding pads and solder ball pads respectively; and a wire bonding metal layer formed on a surface of the chemical plating metal layer of the wire bonding metal layer.