Resin Binder Particles Prevent Pad Cratering in PWB Laminates
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Solution Overview
Problem
Printed wiring board (PWB) laminates experience thermal breakdowns and mechanical failures due to increased thermal exposures and the use of lead-free solder, leading to issues like resin fracture, tail cracking, eyebrowing, and pad cratering, especially with bismaleimide triazine (BT) resin systems.
Innovation Solution
Adding binding particles to the resin system, such as ground glass cloth powder, to reinforce the laminate and prevent adhesive and cohesive failures, while increasing thermal heat transfer and resistance to resin shrinkage and fracture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional resin systems are used in PWB laminates, then manufacturing cost is reduced and ease of manufacture is improved, but the laminate becomes susceptible to thermal breakdown, resin fracture, and pad cratering under increased thermal exposures and lead-free solder conditions
Solution Approach 1:
The patent applies composite materials by combining traditional resin systems with nanotechnology particles (such as silica, alumina, or titania particles in the 1-100 nanometer range) to create an enhanced laminate material. This composite approach maintains compatibility with existing manufacturing processes while providing improved thermal stability and resistance to resin fracture under lead-free solder conditions.
Solution Approach 2:
The patent changes the physical and chemical parameters of the resin system by incorporating nanotechnology particles with specific size ranges (1-100 nanometers) and surface treatments. These parameter changes enhance the resin's thermal stability, reduce shrinkage, and prevent pad cratering without requiring fundamental changes to manufacturing processes.
2Reliability
If lead-free solder is used instead of tin-lead solder, then environmental compliance is improved, but solder reflow temperatures increase by approximately forty degrees Celsius leading to increased thermal breakdown
Solution Approach 1:
The patent changes the thermal parameters of the resin system by incorporating nanotechnology particles that raise the glass transition temperature and improve thermal stability. This allows the laminate to withstand the higher solder reflow temperatures (approximately forty degrees Celsius higher than tin-lead) without experiencing thermal breakdown.
Solution Approach 2:
The patent converts the harmful effect of high solder reflow temperatures into a benefit by using nanotechnology particles to enhance the resin's thermal resistance. The same high temperatures that cause thermal breakdown in traditional resins are now tolerated or even beneficial for achieving proper cure in the enhanced material system.
3Adaptability or versatility
If the number of thermal exposures is increased for complex PWB designs, then design flexibility and functionality are improved, but cumulative thermal effects lead to resin shrinkage and fracture
Solution Approach 1:
The patent uses composite materials incorporating nanotechnology particles to create a resin system that maintains its structural integrity through multiple thermal cycles. The nanotechnology particles act as reinforcement that prevents cumulative thermal damage while allowing the PWB design to incorporate multiple layers and complex routing.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating nanotechnology particles into the resin system prior to manufacturing, which provide preemptive protection against cumulative thermal damage. This preventive approach allows the laminate to withstand multiple thermal exposures without developing resin shrinkage or fracture.
4Reliability
If binding particles are added to the resin system, then resistance to resin shrinkage and fracture is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent changes the particle size parameter to the nanotechnology range (1-100 nanometers), which allows the binding particles to be incorporated into the resin system using modified versions of existing mixing and lamination processes. The small particle size enables uniform distribution without requiring fundamentally new manufacturing equipment or procedures.
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 addition of binding particles enhances the laminate's resistance to thermal exposure and lead-free solder-related failures, reducing occurrences of pad cratering, delamination, and other forms of latent damage, thereby improving the reliability of PWBs.
Implementation Method 1
The binder reinforces the resin system by preventing adhesive and cohesive failure
Implementation Method 2
The binder reinforces the resin system by preventing adhesive and cohesive failure while increasing thermal heat transfer
Implementation Method 3
The addition of the binder increases resistance to resin shrinkage, fracture and embrittlement
Data Source
AI summary
A laminate for a printed wiring board (PWB) in which the laminate has a resin system containing a binder. The binder is made of ultra-fine binding particles that reinforce the resin system thereby reducing adhesive and cohesive failure of the laminate. The particles in addition to reducing occurrences such as pad cratering, eyebrowing, and tail-cracking, have the benefits of increasing thermal heat transfer and reducing resin shrinkage. The particles are preferably the same material as a reinforcing material contained in the laminate which can be a woven glass.