Surface-Mount PCB Corner Mini-Pads for Warpage Mismatch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The warpage of surface-mount packages and printed circuit boards during attachment leads to reduced joint yield, board-level reliability, and system-level reliability due to the formation of solder bridges and short circuits, particularly at the corners where warpage exceeds a critical dimension.
Innovation Solution
Applying mini-pads or raised pads at the corners of the joint area on the printed circuit board to compensate for warpage, ensuring the degree of mismatch is reduced below the critical dimension of the ball grid array, thereby preventing solder bridges during the soldering process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface-mount packages and printed circuit boards are attached during soldering, then electrical connections are established, but warpage causes solder bridges and short circuits that reduce joint yield and reliability
Solution Approach 1:
The patent applies preliminary action by pre-positioning spacers at the corners of the printed circuit board before the soldering process. These spacers are strategically placed to anticipate and counteract the warpage that will occur during heating, thereby preventing solder bridges before they can form. This proactive measure ensures that even as the board warps during soldering, the critical corner regions remain properly aligned.
Solution Approach 2:
The patent introduces spacers as intermediary elements between the printed circuit board and the soldering environment. These spacers act as mediators that physically intervene to maintain proper spacing and alignment during the soldering process, preventing direct contact between solder and adjacent pads that would cause short circuits. The spacers are temporary structures that facilitate reliable joint formation.
2Productivity
If package size is increased to meet high-performance computing requirements, then computing capability is improved, but warpage of the package increases leading to reduced yield
Solution Approach 1:
The patent applies local quality by focusing corrective measures specifically at the corner regions of large packages rather than attempting to control warpage uniformly across the entire package. The spacers are strategically positioned at corners where warpage most critically affects solder joint quality. This localized approach addresses the most problematic areas without requiring complex global warpage compensation, making it feasible for large high-performance computing packages.
Solution Approach 2:
The patent employs parameter changes by modifying the physical state and positioning of corner elements through the introduction of spacers. By changing the vertical position and mechanical support parameters at critical corner locations, the system compensates for thermal expansion and warpage effects that increase with package size. This allows large packages to maintain manufacturing precision despite increased dimensions.
Data Source
AI summary
Methods for improving joinder between a surface-mount package and a printed circuit board are disclosed. The warpage at a corner of the surface-mount package and at a corresponding corner of a joint area on the printed circuit board are measured to determine the degree of mismatch. A mini-pad is applied to the corner between the surface-mount package and the joint area on the printed circuit board. The thickness of the mini-pad pushes against the surface-mount package and the printed circuit board, reducing the degree of mismatch below a critical dimension of a ball grid array of the surface-mount package. The surface-mount package can then be soldered to the joint area, reducing or preventing the formation of solder bridges and short circuits.