Planar Solder Contacts for BGA Mechanical Stress Reduction
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Solution Overview
Problem
Ball Grid Array (BGA) connectors with small solder balls experience mechanical stress and are prone to failure due to short connection height, and the reflowing process for applying solder is complex and time-consuming.
Innovation Solution
A method involving a strip of electrical contacts with tail portions that are attached to an elongate reflowable member, such as solder, which is then cut into separate reflowable elements for secure attachment to the contacts, allowing for a more stable and efficient connection to a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If small solder balls are used in BGA connection, then the connection size is reduced and component density is increased, but the connection height is shortened and mechanical stress resistance is reduced
Solution Approach 1:
The patent transitions from spherical solder balls to planar contact elements with extended tail portions. This dimensional change from 3D spheres to 2D-like planar contacts with extended tails increases the effective connection area and length, providing better mechanical stress resistance while maintaining small footprint.
Solution Approach 2:
The solder connection is segmented into multiple parts: a contact portion for electrical connection and an extended tail portion for mechanical reinforcement. This segmentation allows the tail to bear mechanical stress while the contact portion maintains electrical functionality, resolving the contradiction between small size and stress resistance.
2Reliability
If solder balls are applied by reflowing liquid solder, then secure attachment is achieved, but the process complexity and time consumption increase
Solution Approach 1:
The solder is pre-formed into planar contact elements with integrated tail portions before assembly. This preliminary formation eliminates the need for complex reflow processes during manufacturing, as the pre-formed elements can be directly attached to substrates through simpler heating or mechanical bonding processes.
Solution Approach 2:
The complex reflow process is extracted and replaced by using pre-formed solder elements. The patent removes the liquid solder reflow step entirely, instead using solid pre-formed contact elements that require simpler attachment processes, thereby reducing process complexity while maintaining attachment security.
3Reliability
If solder balls are applied by reflowing liquid solder, then secure attachment is achieved, but the production time increases
Solution Approach 1:
Solder elements are pre-formed off-line before final assembly. This preliminary preparation allows the main assembly process to proceed faster, as the time-consuming liquid solder reflow is replaced by quicker attachment of pre-formed elements, thereby increasing production speed while maintaining attachment reliability.
Solution Approach 2:
The patent skips the time-consuming liquid solder reflow process by using pre-formed solid solder elements. This skipping of the intermediate liquid phase process reduces production time significantly while still achieving secure attachment through the pre-formed elements' design.
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 method provides a stable and efficient electrical connection with reduced mechanical stress and simplifies the solder application process by pre-attaching reflowable elements to the contacts before assembly, enhancing reliability and reducing production time.
Implementation Method 1
The elongate reflowable member is pushed onto the tail portions of the plurality of contacts
Implementation Method 2
reflowable member, such as solder
Data Source
AI summary
A method of fixing reflowable elements on electrical contacts. The method includes providing a strip having a number of electrical contacts, each contact including a contact body and a tail portion extending away from the contact body. The tail portions of the contacts are then disposed adjacent an elongate reflowable member. The elongate reflowable member is pushed onto the tail portions of the plurality of contacts. Subsequently, the elongate reflowable member is cut into a plurality of separate reflowable elements, each reflowable element corresponding to one of the tail portions. The electrical contacts with the reflowable element attached thereto are separated from the strip.