Retaining Plate Chip Positioning in Reconstituted Boards
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Solution Overview
Problem
The displacement of chips during resin encapsulation and polymerization in the manufacturing of reconstituted wafers, which exceeds the positioning tolerances required, and the existing solutions, such as using a copper lattice, either fail to eliminate displacement or limit the number of chips due to space constraints and require additional processing steps.
Innovation Solution
A method involving the use of a retaining plate with a coefficient of expansion close to that of the chips, which is bonded to the chips before resin deposition and partially or totally removed after polymerization, to maintain chip positioning and act as heat transfer elements to manage thermal issues in 3D electronic modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a copper lattice is used as a template to reduce resin dilation, then chip displacement is reduced, but the lattice occupies space and limits the number of chips on the plate
Solution Approach 1:
The invention extracts and removes the copper lattice template after the resin has polymerized and the chips have been secured in their final positions. This allows the lattice to serve its temporary function of preventing resin dilation during molding, then be eliminated to maximize the usable area for chips on the reconstituted plate.
Solution Approach 2:
The copper lattice is placed on the adhesive support before the chips are positioned and before the resin is deposited. This preliminary placement ensures that the lattice is in position to control resin dilation from the start of the molding process, preventing chip displacement before it can occur.
2Manufacturing precision
If a copper lattice is used to maintain chip positioning, then displacement during resin deposition is reduced, but additional processing steps are required
Solution Approach 1:
The copper lattice is discarded after serving its temporary purpose of maintaining chip positioning during resin deposition and polymerization. The lattice is removed in a single additional step after the chips are securely encapsulated, eliminating the need for complex in-situ positioning mechanisms that would require multiple adjustment steps.
3Temperature
If the retaining plate material has a different expansion coefficient than the chips, then thermal management may be improved, but chip displacement during polymerization increases
Solution Approach 1:
The invention carefully selects the expansion coefficient parameter of the retaining plate material to be close to that of the chips (less than 10 ppm/°C). This parameter matching minimizes differential thermal expansion during polymerization, preventing chip displacement while still allowing the metallic plate to provide effective thermal management through its inherent heat conduction properties.
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 effectively maintains chip positioning during and after resin molding, reduces thermal hot spots, and allows for the creation of more densely packed reconstituted plates with improved thermal management in 3D modules.
Implementation Method 1
The material of the chips having an expansion coefficient of approximately 3 ppm/°C, the material of the retaining plate advantageously has an expansion coefficient close to that of the chips, that is to say less than 10 ppm/°C
Implementation Method 2
a step of polymerizing the resin to harden it and thus form a rigid and manipulable substrate in which the chips are fixed
Implementation Method 3
parts of the retaining plate, glued to the chips, are also heat transfer elements which will thus contribute to evacuating the heat emitted by the chips
Data Source
Figure 1~2d
Figure 2e~3c
Figure 4a~4e
AI summary
The invention relates to a method for producing a reconstituted board (1) that comprises chips (10) having connection pads (11) on a surface of said chip, referred to as a front surface (12), wherein the method includes the following steps: positioning the chips (10) on an adhesive substrate (20) with the front surface on the substrate, depositing a resin (50) onto the substrate (20) for encapsulating the chips, and polymerising the resin (50). Before the resin deposition step, the method includes a step of gluing a supporting plate (40) onto the chips for positioning the chips, said supporting plate (40) including portions provided on a surface (12, 13) of the chips.