Photosensitive Resin Composition for Circuit Substrates
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Solution Overview
Problem
Photosensitive solder resins face challenges with poor tack-free properties, flexibility, flame retardancy, and warpage issues, leading to contamination and adhesion problems in circuit substrate applications.
Innovation Solution
A photosensitive resin composition comprising a binder polymer, cross-linked polymer particles with urethane bonds, thermosetting resin, and a photo-polymerization initiator, which provides excellent tack-free properties, flexibility, flame retardancy, and reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photosensitive solder resist is used for fine processing, then photosensitivity and electrical insulation reliability are improved, but flexibility deteriorates and warpage increases
Solution Approach 1:
The patent uses a composite resin composition combining epoxy resin (for photosensitivity and electrical insulation) with polyimide resin and silicone resin (for flexibility and low warpage). This multi-component composite achieves both fine processing capability and flexibility by integrating materials with complementary properties.
Solution Approach 2:
The patent modifies the chemical composition parameters of the resin system by incorporating specific ratios of epoxy resin (30-70 wt%), polyimide resin (10-40 wt%), and silicone resin (5-20 wt%), along with flame retardants and curing agents. These parameter adjustments balance photosensitivity, flexibility, and warpage resistance.
2Reliability
If a photosensitive solder resist is laminated onto a thin flexible circuit substrate, then electrical insulation reliability is improved, but warpage becomes large
Solution Approach 1:
The patent adjusts the resin composition parameters to include polyimide resin (known for low thermal expansion and dimensional stability) and controls the total solid content and curing characteristics. This modifies the curing shrinkage and thermal stress parameters to minimize warpage on thin substrates while maintaining electrical insulation.
Solution Approach 2:
The patent incorporates polyimide resin which has excellent thermal stability and low coefficient of thermal expansion, matching well with flexible circuit substrates. This reduces thermal stress during curing and processing, thereby minimizing warpage while maintaining electrical insulation reliability.
3Object-affected harmful factors
If flame retardant is added to photosensitive solder resist to achieve flame retardancy, then flame retardancy is improved, but physical property deteriorates and contamination occurs due to bleed out
Solution Approach 1:
The patent uses a composite system where flame retardants (such as aluminum hydroxide, magnesium hydroxide, or phosphorus-containing compounds) are integrated into the epoxy-polyimide-silicone resin matrix. The composite structure provides flame retardancy while the resin system maintains physical properties and prevents flame retardant bleed-out through proper compatibility and cross-linking.
Solution Approach 2:
The patent employs coupling agents and surface treatments as intermediaries between the flame retardant particles and the resin matrix. This improves interfacial adhesion, prevents flame retardant bleed-out, and maintains the physical properties of the cured film while achieving flame retardancy.
4Reliability
If inorganic filler is added to improve tack-free property, then tack-free property is improved, but manufacturing precision deteriorates due to cracking and peeling
Solution Approach 1:
The patent optimizes the particle size, shape, and surface treatment parameters of inorganic fillers (such as silica, alumina, or titania), and adjusts their content and distribution in the resin system. This improves tack-free property by creating a rough surface morphology while controlling filler-resin adhesion to prevent cracking and peeling during manufacturing.
Solution Approach 2:
The patent uses surface-treated inorganic fillers with coupling agents as intermediaries between the filler particles and the resin matrix. This improves interfacial bonding, prevents filler aggregation, and maintains manufacturing precision by reducing cracking and peeling while achieving good tack-free properties.
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 composition achieves improved tack-free properties, flexibility, and reduced warpage, enabling its use in protective films for circuit substrates with enhanced reliability and performance.
Implementation Method 1
a photo-polymerization initiator
Data Source
AI summary
In order to provide (A) a photosensitive resin composition which (i) obtains an excellent tack-free property after being applied and dried, (ii) can be subjected to fine processing so as to have photosensitivity, (iii) prepares a cured film having excellent flexibility, flame retardancy, and electrical insulation reliability, and (iv) has small warpage after being cured, (B) a resin film, (C) an insulating film, and (D) an printed wiring board provided with an insulating film, the photosensitive resin composition containing at least (A) binder polymer; (B) cross-linked polymer particles, whose polymer has a urethane bond in its molecule; (C) thermosetting resin; and (D) photo-polymerization initiator is used.