Photosensitive Resin Composition for Hard Disc Drive Circuit Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photosensitive resin compositions used for forming circuits in hard disc drives suffer from high water absorption, leading to warping and reduced alignment accuracy, and low solubility in developing solutions, making it difficult to form precise patterns.
Innovation Solution
A photosensitive resin composition comprising a polymer with a specific repeating unit, a dissolution accelerator, and a solvent, which reduces water absorption and enhances solubility in developing solutions, allowing for the formation of precise patterns through a pattern forming method involving application, exposure, and development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyimide resin layer with low water absorption (containing fluorine) is used, then water absorption is reduced, but solubility in organic solvent as developing solution becomes remarkably low making development difficult
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide resin by introducing specific side chain structures (formula 1 with R1-R6 groups) and controlling the ratio of different structural units (formula 2 and formula 3) to achieve optimal balance between water absorption resistance and solubility. The invention specifies that when the content of structural unit (2) is 20-80 mass% and structural unit (3) is 20-80 mass%, both properties are satisfied simultaneously.
Solution Approach 2:
The patent creates a composite photosensitive resin composition by combining modified polyimide resin with specific additives including dissolution accelerator (compounds with formula 4 or 5), photopolymerization initiator, and organic solvent. This composite formulation enables the resin to achieve both low water absorption and good solubility in developing solution through synergistic effects of the components.
2Ease of manufacture
If the polyimide resin layer has high water absorption, then solubility in developing solution is improved, but the substrate warps and alignment accuracy is reduced
Solution Approach 1:
The patent modifies the polyimide resin structure by introducing specific side chains (formula 1) and controlling the ratio of structural units (formula 2 and 3) to reduce water absorption while maintaining adequate solubility. This structural parameter optimization ensures that the resin absorbs minimal water (<5% by weight) preventing substrate warping while retaining manufacturability through controlled dissolution in developing solution.
3Length of moving object
If the line is made thin to connect head to disc main body, then wire thickness is reduced, but the wire is easily corroded and mounting becomes difficult
Solution Approach 1:
The patent employs a thin-film photosensitive resin coating (5-20 μm thickness) formed on the suspension substrate to create protective circuits and insulation layers. This thin film structure enables fine interconnection lines with adequate mechanical strength and corrosion resistance, replacing conventional thick wire connections while achieving the required electrical connectivity and protection.
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
The solution achieves low water absorption and improved solubility, enabling the formation of reliable electronic parts with high pattern accuracy and sensitivity, particularly suitable for hard disc drive applications.
Implementation Method 1
when the polyimide resin layer has a high water absorption and such a substrate for forming the circuit is incorporated as the suspension in the hard disc drive main body, a dimension is largely altered as the water is absorbed in the polyimide resin layer
Implementation Method 2
a photosensitive resin composition includes (a) a polymer mainly composed of a repeating unit represented by the following general formula (I)... at least one carbon-carbon unsaturated double bond is contained in all repeating units
Data Source
AI summary
A photosensitive resin composition includes (a) a polymer mainly composed of a repeating unit represented by the following general formula (I); (b) a dissolution accelerator for a developing solution; and (c) a solvent:wherein R1 is a trivalent or tetravalent organic group, R2 is a bivalent organic group, R is a monovalent organic group having a carbon-carbon unsaturated double bond or a group represented by O−M+ (M+ represents a hydrogen ion or a cation composed of hydrogen and a compound having the carbon-carbon unsaturated double bond) in which the compound having the carbon-carbon unsaturated double bond is ionically bonded, at least one carbon-carbon unsaturated double bond is contained in all repeating units, m is an integer of 2 or more, and n is 1 or 2.