Printed Wiring Board Via Hole Inversion for Warping Reduction
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Solution Overview
Problem
Existing printed wiring board manufacturing methods require numerous processes to achieve high-density conductor patterns, leading to inefficiencies and potential malconnections with semiconductor devices due to warping and thermal expansion issues.
Innovation Solution
A method involving the use of copper clad laminates or support plates, bonded with thermosetting resin or solder, and forming via holes in opposite directions within resin layers and core layers to minimize warping and enhance adhesion, allowing for efficient multilayer printed wiring board production without omitting essential manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If numerous manufacturing processes are used to form high-density conductor patterns, then manufacturing precision is improved, but productivity deteriorates
Solution Approach 1:
The manufacturing process is divided into two independent sets of processes, each set processing one surface of the laminate. By segmenting the processes this way, both surfaces can be processed simultaneously in parallel, effectively doubling productivity while maintaining the high precision required for dense conductor patterns through standardized process repetition.
Solution Approach 2:
The invention transitions from processing single surfaces sequentially to processing both surfaces simultaneously in the same process steps. This dimensional change in process execution allows parallel operation of manufacturing steps, improving productivity without compromising the precision achieved through multiple process repetitions.
2Stability of the object's composition
If via holes are formed in opposite directions, then warping is reduced, but device complexity increases
Solution Approach 1:
Instead of forming all via holes in the same direction, the invention deliberately forms via holes in opposite directions on opposite surfaces of the laminate. This inverted approach creates compensating thermal expansion effects that cancel out warping, and the complexity is managed through the systematic application of the same process steps to both surfaces.
Solution Approach 2:
The opposite-direction via hole formation exploits thermal expansion principles by creating stress compensation patterns. When the laminate undergoes thermal cycling, the via holes oriented in opposite directions experience compensating expansion and contraction forces that reduce overall warping of the board structure.
3Manufacturing precision
If copper plates are removed to form thin multilayer structure, then manufacturing precision is improved, but loss of substance increases
Solution Approach 1:
The invention extracts and removes copper plates from specific locations where they are not needed for the final thin multilayer structure. By strategically removing copper only from portions where it would create excessive thickness or interfere with precise conductor pattern formation, the process achieves the desired thin laminate structure while minimizing material loss.
Solution Approach 2:
Instead of removing copper plates uniformly from the entire laminate, the invention applies selective removal only to specific local areas where precise thickness control is required. This local quality approach maintains copper plates in areas where structural support or electrical connectivity is needed, thereby reducing overall material loss while achieving the required precision in critical regions.
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 enables the production of high-efficiency printed wiring boards with reduced warping and malconnection risks, maintaining structural integrity and thermal stability, thus improving the reliability of semiconductor device mounting.
Implementation Method 1
bonded with thermosetting resin or solder
Implementation Method 2
heating and pressing a glass woven fabric base material or a glass non-woven fabric base material with copper foils laminated on both sides or one side thereof
Data Source
AI summary
The present invention intends to provide a novel printed wiring board manufacturing method by which printed wiring boards can be manufactured with efficiency. A method of manufacturing a printed wiring board (FIG. 1B) according to the present invention includes a step for preparing two sets of copper clad laminates (FIG. 2A), a step for bonding the copper clad laminates (FIG. 2B), steps for forming lands on both surfaces of a bonded laminate (FIGS. 2C to 2E), steps for forming respective resin layers on both surfaces of the bonded laminate and forming via hole openings to form respective via holes (FIGS. 2F to 2L), a step for forming a resin layer and forming a via hole opening to form a via hole (FIG. 2M), a step for separating the bonded laminate from each other (FIG. 2N) and steps for forming via hole openings from the bonded surface of the separated laminate to form via holes (FIGS. 2O to 2T). Via holes (33-1, 33-2) formed on the resin layer and a via hole (42) formed on the laminate are opened in the opposite directions.