Chip Assembly Carrier Cavities Die Attach Liquid Evaporation
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Solution Overview
Problem
The existing methods for forming chip assemblies are time-consuming and costly, particularly when dealing with a small number of chips on a large leadframe, as they require individual placement and fixing, and often necessitate the use of an intermediate carrier, which increases material costs.
Innovation Solution
A method involving the formation of cavities in a carrier, where a die attach liquid is arranged, and chips with rear side metallization and interconnect material are placed on the liquid, with the liquid then evaporated before the chips are fixed to the carrier, allowing for simultaneous placement and fixation without an intermediate carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual chip placement and fixing is performed sequentially, then each chip can be precisely positioned, but the processing time becomes very long
Solution Approach 1:
The carrier is pre-heated to a temperature between 20°C and 50°C before chip placement. This preliminary heating prevents hot air convection during the fixing process, allowing multiple chips to be placed and fixed simultaneously without image distortion, thereby reducing processing time while maintaining placement precision
Solution Approach 2:
Multiple chip placement and fixing operations are merged into a single simultaneous process. Instead of treating each chip individually, the method allows multiple chips to be placed on the pre-heated carrier and fixed in one batch, combining what were previously separate sequential steps into a unified operation
2Productivity
If an intermediate carrier with adhesive tape is used to hold chips, then multiple chips can be placed at once, but material costs increase due to single-use adhesive tape
Solution Approach 1:
The intermediate carrier and adhesive tape are completely removed from the process. The method places chips directly onto the final carrier (leadframe) using a pick-and-place machine, extracting the unnecessary intermediate step and its associated material costs while maintaining the ability to place multiple chips simultaneously
Solution Approach 2:
The carrier itself serves the dual function of both the placement surface and the final mounting substrate. By pre-heating the carrier and allowing direct chip placement, the system eliminates the need for separate adhesive tapes or intermediate carriers, making the carrier self-sufficient for both placement and fixation functions
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 reduces processing time and costs by enabling the simultaneous placement and fixation of multiple chips on a common carrier, eliminating the need for an intermediate carrier and minimizing material expenses, while maintaining electrical and thermal conductivity.
Implementation Method 1
evaporating the die attach liquid
Data Source
AI summary
A method of forming a chip assembly may include forming a plurality of cavities in a carrier; The method may further include arranging a die attach liquid in each of the cavities; arranging a plurality of chips on the die attach liquid, each chip comprising a rear side metallization and a rear side interconnect material disposed over the rear side metallization, wherein the rear side interconnect material faces the carrier; evaporating the die attach liquid; and after the evaporating the die attach liquid, fixing the plurality of chips to the carrier.