Solder Mask Barrier Layout for Die Attach Resin Bleed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electronic device packages face issues with resin bleed out (RBO) during die attach adhesive application, leading to degraded bonding quality and contamination of sensitive surfaces like wire bond pads, which is exacerbated by reduced form factors and increased surface energy from substrate cleaning.
Innovation Solution
Incorporating a solder mask positioned between the die bond pad and wire bond pads to block adhesive material leakage, using non-electrically conductive epoxy material with a width of 0.1 mm to 0.2 mm, directly on the conductive regions connecting the pads, to prevent adhesive material from spreading onto wire bond pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive material is applied to bond the die to the die bond pad, then bonding strength is improved, but adhesive leakage contaminates the wire bond pads
Solution Approach 1:
A solder mask is introduced as an intermediary barrier element positioned between the die bond pad and wire bond pads. The solder mask has a first portion disposed directly on the conductive region and a second portion extending toward the wire bond pad, creating a physical barrier that prevents adhesive material from migrating from the die bond pad to the wire bond pad while allowing the adhesive to effectively bond the die to the die bond pad.
2Reliability
If substrate cleaning is performed to increase surface energy for better adhesion, then bonding quality is improved, but adhesive leakage is exacerbated
Solution Approach 1:
The solder mask is applied in advance to the conductive regions and wire bond pad areas before die attach adhesive application. This preliminary protective action creates a barrier that counteracts the adhesive bleed out effect that would otherwise be exacerbated by substrate cleaning processes performed to enhance surface energy and adhesion quality.
3Volume of moving object
If form factor is reduced to improve device compactness, then device size is improved, but adhesive leakage becomes more severe
Solution Approach 1:
The solder mask is selectively applied only to specific conductive regions and wire bond pad areas rather than uniformly across the entire substrate. This localized application provides targeted protection against adhesive contamination in critical areas while maintaining the compact form factor and not adding unnecessary material or space.
Data Source
AI summary
An electronic device package may include a solder mask that is positioned to mitigate leakage of resin or other adhesive material from the region of a die and die bond pad onto other surfaces of the package, such as surfaces of wire bond pads. One or more wire bond pads of the package may be formed from the same conductive layer as the die bond pad, and the solder mask may be positioned over a portions of the conductive layer located directly between such wire bond pads and the die bond pad. The solder mask may include portions disposed at one or more sides of the die bond pad. The solder mask may be formed over the package substrate prior to attachment of the die to the die bond pad.