Cap Soldering with Wettable Core and Non-Wettable Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional soldering methods for caps on support layers in electronic packaging often result in voids within the solder joint, leading to incomplete sealing and potential unsealing of packages due to mechanical shocks or reflows.
Innovation Solution
A method involving caps with a wettable core and a non-wettable coating layer, where the cap is coupled with a support layer using a solder paste, with the side surface of the core being the only exposed wettable surface to prevent solder flow into the cap's inner surface, ensuring a void-free sealing ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire surface of the core is covered with a solderable coating layer, then the cap can be soldered to the support layer, but the solder extends along the inner wall of the cap causing voids in the solder joint
Solution Approach 1:
The patent applies local quality by making the coating layer non-uniform: the bottom surface of the cap has a wettable coating layer to promote solder adhesion, while the inner wall has a non-wettable coating layer to prevent solder from climbing up. This spatial differentiation of coating properties ensures the solder fills the gap completely without extending along the inner wall, eliminating voids and ensuring sealing ring integrity.
2Strength
If conventional solder reflow technique is used, then the cap can be made integral with the support layer, but the package may become unsealed due to mechanical shocks or reflows
Solution Approach 1:
The patent uses local quality by applying different coating properties to different surfaces of the cap. The bottom surface has a wettable coating that ensures strong solder bonding to the support layer, while the inner wall has a non-wettable coating that prevents solder from climbing and forming voids. This creates a robust sealing ring that maintains package integrity under mechanical shocks and reflow conditions.
Solution Approach 2:
The patent employs composite materials by combining wettable and non-wettable coating layers on the cap. This composite coating structure allows the cap to simultaneously achieve strong solder adhesion at the bonding interface and prevent solder infiltration into the cap interior, resulting in a reliable sealed package that withstands mechanical stress and thermal reflows.
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 method forms a resilient, void-free sealing ring between the cap and support layer, enhancing package sealing and resistance to mechanical shocks and multiple reflows.
Implementation Method 1
The coating layer 5 is made up of a so-called 'wettable material', which, upon contacting a solder paste and following a thermal treatment, can form an intermetallic compound with the solder contained in the solder paste.
Data Source
AI summary
One embodiment discloses a method for soldering a cap for an integrated electronic device to a support layer, including the steps of: providing a support layer; providing a cap including a core of a first material and a coating layer of a second material, the first and second material being respectively wettable and non-wettable with respect to a solder, the coating layer being arranged so as to expose a surface of the core; coupling the cap with the support layer; and soldering the surface of the core to the support layer, by means of the solder.