Solder Bump Height Stabilization via Intermediary Plate
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Solution Overview
Problem
Conventional solder bump production techniques struggle to form consistent and uniform solder bumps for electrically connecting head sliders to suspension assemblies in hard disk drives, especially with the increasing number of small electrode pads and decreasing gap widths, leading to yield decline due to poor and open solder joints.
Innovation Solution
The use of a height stabilizer plate composed of heat-resistant materials like glass, ceramic, or stainless steel to stabilize and contain low-density, low-viscosity solder paste during the reflow process, ensuring uniform solder bump formation and shape control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional solder bump production techniques are used, then the process is simple, but the solder bump formation becomes inconsistent and non-uniform, leading to poor and open solder joints
Solution Approach 1:
A height stabilizer plate is introduced as an intermediary tool during the reflow process. This plate contacts the solder paste and prevents excessive spreading and height variation, thereby producing uniform solder bumps. The plate acts as a mediator between the solder paste and the electrode pads, controlling the solder bump geometry without requiring complex equipment.
Solution Approach 2:
The invention changes the physical parameters of the solder paste by using low-density, low-viscosity material that flows differently during reflow. Combined with the height stabilizer plate, this parameter change enables precise control of solder bump height and shape, achieving consistent results across multiple bumps.
2Reliability
If the number of electrode pads increases and gap widths decrease, then the electrical interconnection density improves, but the solder joint reliability declines due to poor and open solder joints
Solution Approach 1:
The height stabilizer plate serves as a mediator that ensures consistent solder bump formation even at small dimensions. By controlling the solder paste spreading and height uniformly across all electrode pads, the plate enables reliable solder joints at high interconnection densities where conventional methods fail.
Solution Approach 2:
Using low-density, low-viscosity solder paste changes the material parameters to enable precise control at micro-scale dimensions. This parameter change allows the solder paste to flow appropriately under the height stabilizer plate, creating reliable joints even when gap widths are small and interconnection density is high.
3Ease of manufacture
If low-density, low-viscosity solder paste is used, then the solder paste spreads more easily, but the solder bump height becomes unstable and non-uniform
Solution Approach 1:
The height stabilizer plate acts as a mediator that provides mechanical constraint to the low-density, low-viscosity solder paste during reflow. This constraint prevents excessive spreading and height variation, thereby achieving uniform solder bump heights while still benefiting from the ease of application of the low-viscosity paste.
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 the reliable and repeatable formation of uniform solder bumps with desired shapes and heights, addressing the challenges of small pad sizes and gap widths, thereby improving the electrical interconnection yield and reliability in hard disk drives.
Implementation Method 1
The use of a height stabilizer plate composed of heat-resistant materials like glass, ceramic, or stainless steel to stabilize and contain low-density, low-viscosity solder paste during the reflow process
Implementation Method 2
a height stabilizer plate composed of heat-resistant materials like glass, ceramic, or stainless steel
Data Source
AI summary
Approaches to pre-forming solder bumps, such as for use in electrically connecting a head slider and a suspension assembly for a hard disk drive, involves applying a height stabilizer plate over a shared solder paste applied over a substrate housing electrode pads, and reflowing the solder paste with the plate applied to create solder bumps electrically coupled to the pads. Use of such a plate functions to stabilize and contain the solder paste and create uniform solder bumps across the series of pads, where the plate may be composed of a heat-resistant and anti-solder-wetting material. The solder bump pre-forming techniques generally enable solder bonding of extremely small electrical interconnection pads.