Implant Header Bonding With Thermally Activatable Polyurethane Film
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Solution Overview
Problem
The challenge in bonding header assemblies made of thermoplastic polyurethanes to titanium or titanium alloy housings using liquid silicone adhesives is the difficulty in automating the process due to the liquid state, lengthy curing times, high temperatures, and low mechanical strength of the resulting materials.
Innovation Solution
A method involving a thermally activatable adhesive film, such as thermoplastic polyurethane films, is used to bond the header assembly to the housing by applying the film to the surfaces and joining them under heat and pressure, forming a structurally bonded composite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If liquid silicone adhesives are used to bond header assemblies to housing, then bonding between thermoplastic polyurethane and titanium is achieved, but the process is difficult to automate and has lengthy curing times
Solution Approach 1:
The patent changes the physical state of the adhesive from liquid to solid film form. This parameter change eliminates the need for complex mixing and dosing equipment, allowing simple automated application methods such as pick-and-place or roll-to-roll processes to be used instead of complex liquid handling systems.
Solution Approach 2:
The adhesive is applied in advance as a solid film on one of the bonding surfaces before the actual bonding process. This preliminary action eliminates the need for complex automated mixing and dosing equipment during the bonding process itself, as the adhesive is already prepared and positioned for bonding.
2Productivity
If liquid silicone adhesives are used, then bonding is achieved, but curing duration is typically in the range of hours
Solution Approach 1:
The patent utilizes phase transition of the adhesive from solid film state to bonded state through thermal activation. The solid adhesive film undergoes a phase change when heated, activating the bonding process rapidly in seconds rather than requiring hours of curing time associated with liquid adhesive systems.
Solution Approach 2:
The patent changes the temperature parameter to activate the adhesive bonding process. By heating the assembly to a specific temperature range, the solid adhesive film rapidly transitions to a bonded state, reducing curing time from hours to seconds and significantly improving productivity.
3Strength
If liquid silicone adhesives are used with high temperatures, then bonding is achieved, but the cured materials have low mechanical strength
Solution Approach 1:
The patent optimizes the temperature parameter for thermal activation, using controlled heating to activate the solid adhesive film. This parameter optimization enables the formation of strong, reliable bonds with high mechanical strength while ensuring media-tight connections, overcoming the limitation of low strength in conventionally cured liquid adhesives.
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 approach allows for automated application of a solid adhesive film, reduces curing time to seconds, and enhances mechanical strength, providing a media-tight connection between the components.
Implementation Method 1
applying an adhesive film that is thermally activatable to the first surface and/or to the second surface, and pressing the first and the second surface against one another with the respective film therebetween upon heating the respective film to join the header assembly to the housing
Data Source
Figure 1
AI summary
The present invention relates to a method for connecting a header assembly (1) to a housing (2) of an implantable medical device, the method comprising: providing a header assembly (1) having a first surface (1a) and providing a housing (2) of the implantable medical device, the housing (2) having a second surface (2a) to be connected to the first surface (1a), applying a film (3) that is thermally activatable to the first surface (1a) and/or to the second surface (2a), and pressing the first and the second surface (1a, 2a) with the film (3) therebetween against one another upon heating the film (3) to join the header assembly (1) to the housing (2).