What is a Trace Gimbal Assembly?

    Traditionally suspensions have used extremely fine wires to transmit the signals from the magnetic head to the disk drive's circuitry. Before the mid 90’s, electrical connections were made on suspensions using individual wires manually attached to disk drive suspensions. Starting in the mid 90’s the hard disk drive industry transitioned away from using individual wires to using flex circuit as the number of electrical interconnects increased from 2 to 4 on suspensions. The use of flex circuit’s on suspensions has evolved to what is referred to as a Trace Gimbal today. The Trace Gimbal design uses flex circuit processing technology to semi-additively build up a circuit on top of a stainless steel gimbal. During the suspension assembly process the Trace Gimbal is welded to the base plate and load beam components to make a suspension known as a Trace Gimbal Assembly (TGA).

Trace Gimbal (TG) Technology Benefits:

• Ability to reduce trace and space features through the years as more electrical interconnects are required. Today’s TG’s achieve leading edge 15um trace and space features with a path forward to 10um feature size in volume production in near future.

• Offer the ability to make very thin circuit constructions, which has allowed gimbal stiffness’s to be reduced over time. Current TG’s use stainless steel as thin as 15um with circuits as thin as 24-17um on top of the stainless steel.

• Uses polyimide base layer and covercoat for the following benefits:

  • CTE matched to Stainless Steel and Copper for low curl during thermal cycling.

  • High thermal Resistance > 350C allowing for high temperature processing.

  • Optimized for low CHE properties to provide improved stability to humidity changes.

• Uses photolithography and etching processes to create very complex stainless steel and circuit gimbal features. This provides suspension designers with a large amount of design flexibility to achieve the mechanical specifications of today’s suspensions.

• Have the ability to provide leading edge circuit constructions including interleave and stack trace, which will allow suspension designers to meet the high bandwidth and low impedance of future drive designs.

• Offers the ability to use metal via and direct gold plating onto the stainless steel gimbal for superior grounding connections which is a critical technology for gimbal based micro-actuation and HAMR.