Novel bonding structure for a hard disk drive suspension using anisotropic conductive film

Abstract

A plurality of bonding structures and their forming methods for bonding a FPC to a bonding pad, in particular a bonding pad of a wireless suspension in a head gimbal assembly, using anisotropic conductive adhesive; such structures eliminate the spring-back force in typical anisotropic bonding to ensure durable bonding. At the same time, these structures also allow for reworkability under which the bonded parts can be separated easily.

Description

BACKGROUND OF THE INVENTION [0001] This invention generally relates to the field of disk drives, and more particularly to forming optimal structures for bonding in a head gimbal assembly using anisotropic conductive adhesive. [0002] With the rapid progress of miniaturizing and thinning technology for electronic devices, high-density inner wiring systems including flex-print circuit (FPC) have become essential. At the same time, micro-connecting technology for the connection of FPC with other electronic parts, such as the traces on a magnetic head suspension assembly, is indispensable. [0003] Traditionally the FPC is capable of adopting ultrasonic bonding. The connecting terminals of the FPC are plated with gold; the flying leads of the FPC are aligned with and pressed to the bonding pad on the suspension with sufficient force to keep the alignment and atomic interdiffusion of the flying leads and the underlying metallization, which process ensures the intimate contact between the tw...

AI Technical Summary

Benefits of technology

"The present invention provides a new way to bond parts in a head gimbal assembly (HGA) using an anisotropic conductive adhesive. This method simplifies the bonding process and reduces the size of the bonding pads, which helps to accommodate the trend towards miniaturization of the disk drives and the head assemblies. The invention also improves capacity in the bonding process and reduces parasitic capacitance, which will increase the data rate of the hard disk drive. Additionally, the invention allows for direct bonding of the FPC to the contact pad without an overcoat layer, or by using a conductive structure shaped like a ball and plated with gold or other conductive materials. Overall, the invention provides a more efficient and reliable method for bonding parts in an HGA."

Problems solved by technology

However, the pressing of the flying leads of the FPC entails complex processing, and ultrasonic bonding to different bonding pads is very difficult to contact.

Moreover, bonded parts cannot be separated in the future to be reworked without damaging the FPC or the suspension.

However, this process requires forming metal cores and solder bumps for soldering.

The metal cores incur extra expenses, and soldering has to be performed at high temperatures typically over 180 degrees Celsius.

Furthermore, both ultrasonic bonding and soldering are becoming increasingly expensive because of high cost of labor and parts of the FPC.

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