Post-Adjacent Solder Joint Structure for Crack-Resistant Bumps
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Solution Overview
Problem
The reliability of solder bumps in semiconductor packages is compromised by high stress, leading to cracks and potential failure, which affects manufacturing yield and device performance.
Innovation Solution
A semiconductor device structure featuring a post on an under bump metallurgy (UBM) pad with a concave solder joint that minimizes stress and prevents crack propagation by forming a controlled wetting angle, thereby enhancing the durability of the solder bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder bumps are used to mount carriers, then electrical connection and integration are achieved, but high stress causes cracks and reliability failures
Solution Approach 1:
The invention divides the solder bump structure into two distinct parts: a spherical solder ball and a separate metal post. The metal post is embedded within the solder ball, creating a composite structure where the post acts as an internal reinforcement element. This segmentation allows the post to bear mechanical stress while the solder ball maintains electrical connection, thereby resolving the contradiction between reliability and stress resistance.
Solution Approach 2:
The invention creates a composite structure by combining two different materials: solder material (forming the spherical ball) and metal material (forming the post). The metal post is embedded within the solder ball, forming a composite solder bump that leverages the electrical conductivity of solder and the mechanical strength of metal. This composite approach directly addresses the stress resistance issue while maintaining reliability.
2Productivity
If smaller semiconductor devices are manufactured, then circuit board density increases, but solder bump stress concentration increases leading to higher failure rates
Solution Approach 1:
By segmenting the solder bump into a spherical solder ball and an embedded metal post, the invention creates a structure where the post provides internal reinforcement. This segmentation allows the solder bump to maintain small size for high density applications while the metal post prevents stress concentration and crack propagation, thereby maintaining reliability even in miniaturized devices.
Solution Approach 2:
The invention applies local quality by concentrating the metal post specifically at the base of the solder ball where stress concentration occurs during mounting. This localized reinforcement at the critical stress point allows the overall solder bump to remain small for high density circuits while providing enhanced durability where it is most needed.
3Ease of manufacture
If conventional solder bump structures are used, then manufacturing is simple, but crack propagation occurs reducing manufacturing yield
Solution Approach 1:
The invention applies preliminary action by pre-embedding the metal post into the spherical solder ball before the solder bump is applied to the substrate. This pre-formed composite structure ensures that the reinforcement is already in place before mounting, preventing crack initiation and propagation during subsequent manufacturing steps. The preliminary formation of the composite structure maintains manufacturing simplicity while improving yield.
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 design reduces the likelihood of crack formation and propagation, improving the reliability and longevity of the solder bumps and the overall semiconductor device by distributing stress effectively.
Implementation Method 1
disposing a joint adjacent to the post and the first pad to form a first contact interface between the first pad and the joint and a second contact interface between the post and the joint
Implementation Method 2
heat-treating the joint
Data Source
AI summary
A method of manufacturing a semiconductor device includes providing a carrier, disposing a first pad on the carrier, forming a post on the first pad, and disposing a joint adjacent to the post and the first pad to form a first entire contact interface between the first pad and the joint and a second entire contact interface between the first pad and the post. The first entire contact interface and the second entire contact interface are flat surfaces.