PCB Pad Recesses for Passive Element Adhesion
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Solution Overview
Problem
The adhesive force between passive elements and pads on semiconductor modules is relatively weak due to the conventional reflow process using solder, leading to potential disconnections under mechanical stress.
Innovation Solution
The design incorporates pads with recesses on a printed circuit board that match the size and shape of passive element electrodes, allowing for secure insertion and bonding with a solder layer that surrounds the passive element, enhancing the adhesion force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflow process using solder is used to bond passive elements to pads, then the bonding process is simple and efficient, but the adhesive force between passive elements and pads is relatively weak
Solution Approach 1:
The invention transitions from a two-dimensional surface bonding approach to a three-dimensional embedded structure. Recesses are formed on the pad surfaces, allowing passive elements to be inserted and bonded in a volumetric manner rather than merely on the surface, thereby significantly enhancing adhesive force while maintaining bonding efficiency
Solution Approach 2:
The passive elements are nested within recesses formed on the pad surfaces. This nesting structure allows the passive elements to be embedded into the pad structure, creating a more robust mechanical interlock and stronger adhesive bonding compared to surface-level attachment
2Ease of manufacture
If conventional surface mounting is used without recesses, then the manufacturing process is simpler, but displacement under load is significant and reliability is reduced
Solution Approach 1:
The invention adds vertical depth to the bonding interface by forming recesses on pad surfaces. This dimensional addition creates mechanical interlocking that significantly reduces displacement under load, thereby improving reliability while maintaining ease of manufacture through standard PCB fabrication processes
Solution Approach 2:
Recesses are pre-formed on the pad surfaces during PCB manufacturing before passive element assembly. This preliminary action prepares the bonding interface in advance, ensuring optimal alignment and reducing displacement during subsequent assembly and operation, thereby improving reliability without complicating the overall manufacturing 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 configuration significantly reduces displacement under load, reinforcing the adhesion between passive elements and pads, thereby improving the reliability of semiconductor modules.
Implementation Method 1
the passive element on the pads may be typically bonded to the pads by a reflow process using a solder
Data Source
AI summary
A printed circuit board (PCB) includes: an insulation substrate; a first pad on the insulation substrate; and a second pad on the insulation substrate and spaced apart from the first pad, wherein the second pad has a size substantially the same as a size of the first pad, wherein the first pad includes a first recess configured to receive a first electrode of a passive element, wherein the second pad includes a second recess receiving a second electrode of the passive element, wherein the first recess has a depth substantially the same as a thickness of the first pad, wherein the second recess has a depth substantially the same as a thickness of the second pad, wherein each of the first recess and the second recess exposes an upper surface of the insulation substrate.