Through-Plating Printed Circuit Boards with Area-Dividing Screens
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Solution Overview
Problem
The existing through-plating methods for printed circuit boards with sintered ceramic substrates require multiple filling operations for holes of different diameters, leading to material excesses, increased costs, and thermal treatment complications, which complicates the filling process and reduces the reliability of the metallization.
Innovation Solution
A method using a printing screen with area-reducing and area-dividing geometry to fill multiple holes of varying diameters simultaneously under compression pressure, reducing the number of filling operations and thermal treatments, and utilizing a metal-containing sintering paste with palladium for improved bonding and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple filling operations are performed for holes of different diameters, then each hole can be filled with appropriate material amount, but the number of filling operations and thermal treatments increases, leading to process complexity and material excesses
Solution Approach 1:
The screen opening is divided into multiple independent filling zones (first filling zone, second filling zone, third filling zone) with different opening sizes. Each zone corresponds to holes of specific diameter ranges, allowing selective filling of appropriate material amounts for different hole sizes in a single operation, thereby avoiding material excesses while reducing process complexity
Solution Approach 2:
A single screen structure serves multiple functions by incorporating filling zones with different opening sizes that can simultaneously fill holes of various diameters. The screen structure acts as both a template for material deposition and a control mechanism for material distribution, eliminating the need for multiple separate filling operations
2Device complexity
If a single filling operation is used for all holes, then process complexity is reduced, but holes of different diameters cannot receive appropriate material amounts, leading to material excesses or deficiencies
Solution Approach 1:
Different regions of the screen structure have different opening sizes (first filling zone with larger openings, second filling zone with medium openings, third filling zone with smaller openings) that are locally optimized for specific hole diameter ranges. This local differentiation ensures that each hole receives the appropriate material amount based on its size, achieving high filling precision while maintaining a simple single-step process
3Manufacturing precision
If compression pressure is applied during filling, then material distribution is improved and material excesses are avoided, but additional equipment and process control are required
Solution Approach 1:
The filling process combines screen printing with compression pressure application in a single integrated operation. The screen structure guides material deposition while simultaneous compression ensures proper material distribution and eliminates excesses, merging two functions (pattern transfer and material consolidation) into one step that improves precision without requiring separate equipment
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 minimizes material and operational costs, ensures failsafe through-plating with sufficient conductive material, reduces thermal treatment operations, and prevents metal migration, resulting in a more reliable and efficient metallization process.
Implementation Method 1
a multitude of holes in the ceramic substrate of different hole diameters are filled simultaneously under compression pressure with a metallic sintering paste
Implementation Method 2
The ceramic substrate is then dried and fired in a sintering furnace, with the result that the thick-layer paste or sintering paste fully sinters and enters into a cohesive bond with the ceramic substrate
Data Source
AI summary
A method of through-plating a circuit board having conductors formed on two sides. At least two holes are filled under compression pressure with a sintering paste. Subsequently, the sintering paste is dried and fired to form a cohesive bond with the ceramic substrate and fill the holes. Simultaneous filling of multiple holes having different hole diameters is accomplished using a printing screen with screen holes of different diameters. A single print parameter set is used. The printing screen here has at least one screen hole for filling a hole larger than the reference hole. The screen hole has an area-reducing and area-dividing geometry that divides the screen hole into at least two hole sections.