PCB Underfill Dispenser Shielding to Prevent Premature Curing
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Solution Overview
Problem
Existing underfill processes face challenges in applying consistent heat to large circuit boards, particularly those of odd shapes, leading to difficulties in accessing components and preventing heat contamination that causes premature crosslinking of underfill within the dispenser, resulting in clogging and improper dispensing.
Innovation Solution
An apparatus and method utilizing a dispensing end effector with a robotic arm, controlled by a dispense controller, and a protective enclosure, which includes a dispenser with heat shielding and cooling features to prevent premature curing of underfill, allowing for precise application and distribution on large circuit boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If heat is applied to large circuit boards for underfill process, then capillary action is enhanced and underfill flows under components, but heat contamination causes premature crosslinking of underfill within the dispenser, resulting in clogging
Solution Approach 1:
The system divides the heating process into spatially separated zones: the dispenser remains in a cool environment while the board is heated in a separate heating zone. This segmentation allows heat application to promote capillary action without exposing the underfill in the dispenser to premature crosslinking temperatures.
Solution Approach 2:
The system introduces an intermediary heating zone between the dispenser and the board components. This intermediary zone allows controlled heat application to the board without directly heating the dispenser, enabling capillary action while preventing premature underfill curing in the dispenser.
2Ease of operation
If conventional underfill processes are used on large boards, then components can be underfilled, but it becomes difficult to access components on large boards and apply consistent heat
Solution Approach 1:
The system replaces manual or simple mechanical heating methods with a controlled thermal field system. Multiple heating zones can be independently controlled to provide consistent heat distribution across large boards, ensuring uniform capillary action and underfill flow regardless of board size or component location.
Solution Approach 2:
The system transitions from point-to-point heat application to a distributed thermal field approach. By creating a controlled thermal environment that envelops the board, the system achieves consistent heat application across the entire board surface, enabling reliable underfilling of components anywhere on large boards.
3Stability of the object's composition
If underfill crosslinks within the dispenser, then the underfill hardens and can no longer move, but this causes clogging and prevents proper dispensing
Solution Approach 1:
The system applies preliminary cooling or heat shielding to the dispenser to prevent the underfill from reaching crosslinking temperatures before dispensing. This preliminary anti-action counteracts the natural tendency of underfill to cure, maintaining its fluid state for proper dispensing while still allowing crosslinking to occur after application to achieve structural stability.
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
Enables effective underfill dispensing on boards up to 48 inches in diameter, preventing crosslinking and clogging, ensuring consistent application and mechanical stability of components through controlled heating and cooling mechanisms.
Implementation Method 1
cooling features to prevent premature curing of underfill
Implementation Method 2
heat shielding and cooling features to prevent premature curing of underfill
Implementation Method 3
as underfill is the result, in most processes, of a capillary action by which the underfill flows under the component in the presence of heat
Data Source
AI summary
An apparatus, system and method for dispensing underfill to components on a printed circuit board. The apparatus, system, and method includes a dispensing end effector suitable for dispensing underfill to components on a printed circuit board within an underfill chamber. The dispensing end effector may include: an electromechanical connection to at least one dispensing robot arm capable of physically situating the dispensing proximate to the circuit board; a communicative connection to a dispense controller capable of communicatively controlling at least the dispensing; a dispenser which includes an underfill output port, which is capable of the dispensing, and which is removably mounted to the electromechanical association; and a protective enclosure at least substantially about the dispenser.