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Publication Number
US-11571692-B2
Publication Date
2023-02-07
Expiration Date
Abstract
A microfluidic device includes a silicon device and a metallic component. The silicon device and the metallic component are attached by preparing a surface of a silicon device to be solderable, preparing a corresponding surface of a metallic component to be solderable, and soldering the prepared surface of the silicon device to the corresponding prepared surface of the metallic component with a solder of a pre-defined composition and thickness to accommodate strain due to co-efficient of thermal expansion (CTE) mismatch between the silicon device and the metallic component.
Core Innovation
The invention relates to an attachment method for a microfluidic device that includes a silicon device and a metallic component joined by a solder joint. The silicon device includes a first solderable surface and the metallic component includes a second solderable surface, and the solder joint attaches the first solderable surface to the second solderable surface using a homogenous single composition solder.
The solder joint has a pre-defined thickness configured to accommodate strain due to co-efficient of thermal expansion (CTE) mismatch between the silicon device and the metallic component without breaking apart. The disclosed approach specifies that the homogenous single composition solder is an indium silver solder, including silver-indium solder with 97% indium by weight in the recited example, and the melting point or solidus point is less than or equal to 160 C.
The document further describes hermetically joining a silicon MEMS microfluidic pump to a metallic manifold using a metallurgical connection that is sized for CTE mismatch strain accommodation. Because silicon and titanium are difficult to directly wet or solder, the disclosed concept includes metallizing both mating surfaces before forming the solder joint, and it also describes redundant sealing concepts and multiple surface-preparation approaches.
Claims Coverage
The partial content includes two independent claims that both focus on the same core device structure: a silicon device with a solderable surface joined to a metallic component by a homogenous single composition indium-silver solder joint having a pre-defined thickness for CTE-mismatch strain accommodation. Across the independent claims, the coverage centers on the solder joint thickness/CTE-mismatch relationship and the low-melting indium-silver solder selection defined by melting point/solidus point.
Microfluidic device with homogenous indium-silver solder joint thickness for CTE mismatch accommodation
A microfluidic device comprising a silicon device including a first solderable surface, a metallic component including a second solderable surface, and a solder joint attaching the first solderable surface to the second solderable surface, the solder joint comprising a homogenous single composition solder and having a pre-defined thickness configured to accommodate strain due to co-efficient of thermal expansion (CTE) mismatch between the silicon device and the metallic component without breaking apart.
Indium-silver solder joint with low solidus point for microfluidic device CTE mismatch accommodation
A microfluidic device comprising a silicon device including a first solderable surface, a metallic component including a second solderable surface, and a solder joint connected to the first solderable surface and to the second solderable surface, the solder joint comprising a homogenous single composition solder and having a pre-defined thickness configured to accommodate strain due to co-efficient of thermal expansion (CTE) mismatch between the silicon device and the metallic component, wherein the homogenous single composition solder is an indium silver solder, the pre-defined thickness is greater than or equal to 25 μm, and the solidus point of the solder is less than or equal to 160 C.
Across the independent claims, the inventive focus is the use of a homogenous single composition indium-silver solder joint with a pre-defined thickness selected to accommodate CTE-mismatch strain between silicon and a metallic component without breaking apart, with the solder limited to a low melting/solidus point (<=160 C).
Stated Advantages
Accommodate strain due to CTE mismatch between the silicon device and the metallic component without breaking apart.
Documented Applications
No documented applications found
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