Multilayer Wiring Board Inspection Using Temporary Support to Prevent Warpage
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Solution Overview
Problem
Existing methods for electrical inspection of thin multilayer wiring boards face challenges such as warpage, making accurate positioning and probing difficult, and are limited to continuity tests, unable to perform insulation tests without releasing support layers.
Innovation Solution
A method involving a laminated sheet with a first support, first release layer, and metal layer, alternately stacking wiring and insulating layers, bonding a second support with an opening to the multilayer laminate, releasing the first support, and using conductors to contact connection pads for inspection, which reduces warpage and enables accurate probing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If thin multilayer wiring boards are used to reduce weight and miniaturize boards, then weight and size are reduced, but strength decreases leading to warpage that makes accurate positioning and probing difficult
Solution Approach 1:
A support layer is bonded to the multilayer laminate before electrical inspection to prevent warpage. This preliminary support structure maintains the flatness and dimensional stability of the thin multilayer board during the inspection process, enabling accurate probing without compromising the final lightweight design.
2Productivity
If thin multilayer wiring boards are used to increase mounting density, then mounting density increases, but handling properties deteriorate due to reduced strength
Solution Approach 1:
The support layer is attached in advance to provide mechanical strength and improve handling properties during inspection operations. This allows high-density multilayer boards to be handled and inspected accurately without compromising the mounting density achieved through thinning.
3Device complexity
If conventional inspection methods with flat plate jigs are used, then inspection setup is simple, but accurate positioning fails due to warpage of thin boards
Solution Approach 1:
The support layer is bonded to the multilayer laminate before inspection to maintain flatness and enable accurate positioning. This preliminary reinforcement allows the use of simple flat plate jig structures while achieving high positioning accuracy that would otherwise require complex positioning systems.
4Adaptability or versatility
If support layers and high-resistance conductive layers are removed to perform insulation tests, then insulation testing becomes possible, but warpage occurs making inspection difficult
Solution Approach 1:
The support layer is bonded in advance to prevent warpage that would occur after removing the high-resistance conductive layer. This allows insulation tests to be performed on fully processed multilayer boards with both surfaces accessible, maintaining flatness throughout the inspection process.
Solution Approach 2:
The support layer acts as an intermediary structure that enables insulation testing by providing mechanical stability. It allows probes to access both surfaces of the multilayer board for insulation testing without causing warpage, serving as a temporary structural mediator during the inspection process.
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 ensures accurate electrical inspection by reducing warpage and allowing for both continuity and insulation tests on thin multilayer laminates, improving connection reliability and flatness.
Implementation Method 1
bonding a second support having an opening on a surface, remote from the laminated sheet, of the multilayer laminate with a second release layer therebetween
Data Source
AI summary
Provided is a method of manufacturing a multilayer wiring board, in which electrical inspection can be performed with accurate probing while warpage of a multilayer laminate is reduced. This method includes providing a laminated sheet including a first support, a first release layer and a metal layer; alternately stacking wiring layers and insulating layers on a surface of the metal layer, wherein an n-th wiring layer being the uppermost layer includes an n-th connection pad; bonding a second support having an opening on a surface, remote from the laminated sheet, of the multilayer laminate with a second release layer therebetween such that at least a part of the n-th connection pad is disposed within the opening; releasing the first support from the reinforced multilayer laminate at the first release layer; and putting conductors into contact with the n-th connection pads of the reinforced multilayer laminate to perform electrical inspection.