Shielded Module Mounting on PCB With Depressed Solder Layer
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Solution Overview
Problem
Miniaturization of DC-DC converters leads to increased fragility of common ground electrode layers, making reliable grounding and mounting of shielded modules on printed wiring boards challenging, and variations in solder paste application can result in irregular component mounting.
Innovation Solution
A structure and method involving a mounting substrate with a shielding layer and a solder layer, where the solder layer is depressed to reduce solder volume while maintaining bonding strength, and a ground terminal connected to a surface electrode for improved grounding and shielding, along with a solder rejecting layer to prevent solder climbing and ensure reliable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the common ground electrode layer is miniaturized to reduce module size, then the module size is reduced, but the ground electrode layer becomes more likely to be broken and harder to connect reliably to the metal casing
Solution Approach 1:
The ground electrode layer is extended from a two-dimensional planar structure to a three-dimensional structure by forming protrusions that extend toward the metal casing. This vertical extension in the third dimension increases the connection area and reliability without increasing the planar footprint, thus maintaining miniaturization while improving grounding reliability.
Solution Approach 2:
The ground electrode layer is pre-formed with protrusions that extend toward the metal casing before assembly. This preliminary structuring ensures that when the module is assembled, the protrusions automatically provide reliable connection points to the metal casing, eliminating the need for additional grounding measures and ensuring consistent grounding reliability.
2Quantity of substance
If a depressed portion is formed in the solder layer to reduce solder volume, then solder usage is reduced, but the bonding strength between module and printed wiring board may be compromised
Solution Approach 1:
The solder layer is designed with non-uniform thickness, featuring a depressed portion in the central area and thicker edges. This local variation in quality allows the solder to concentrate bonding material at the critical edge regions where bonding is most needed, while reducing material usage in the less critical central area, thus maintaining bonding strength while reducing overall solder volume.
Solution Approach 2:
The solder layer is formed as a composite structure combining a depressed central portion with raised edge portions. This composite configuration optimizes the distribution of bonding material, ensuring adequate bonding strength at the interfaces while minimizing total solder consumption through the strategic placement of solder material in high-stress regions.
3Reliability
If variations in solder paste application occur, then module mounting becomes irregular and reliability is impaired, but increasing solder paste application control may increase manufacturing complexity
Solution Approach 1:
The solder layer is pre-formed with a depressed portion configuration before module assembly. This preliminary structuring creates a self-aligning feature that compensates for variations in solder paste application, as the depressed portion naturally guides and accommodates solder flow during reflow, ensuring consistent bonding regardless of initial solder paste variations, thus maintaining mounting reliability without increasing manufacturing complexity.
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 configuration enhances the reliability and stability of module mounting by reducing solder usage, improving bonding strength, and ensuring reliable grounding and shielding, while preventing irregular mounting and solder climbing, thus providing a high-shielding effect and liquid tightness.
Implementation Method 1
connecting, by melting and solidifying the pre-applied solder, the shielding layer to a surface electrode located on the printed wiring board via the melted and solidified pre-applied solder
Data Source
AI summary
In a structure for mounting a shielded module on a printed wiring board, the shielded module includes a mounting substrate, a shielding layer, and a solder layer. Electronic components are mounted on a main surface of the mounting substrate. The shielding layer is provided in an area from above the mounting substrate to a side surface of the mounting substrate and covers the electronic components. The solder layer is provided on a side surface of the shielding layer. The shielding layer is connected to a surface electrode located on the printed wiring board via the solder layer. The surface of the solder layer is depressed.