Signal Pad Solder Mask Geometry for Lead Self-Alignment

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Solution Overview

Problem

Existing device packages face misalignment issues between leads and pads during the solder reflow process, leading to faulty devices that cannot be tested or shipped.

Innovation Solution

The device package incorporates a solder mask material on the pads to promote self-alignment of leads by configuring the pad width and solder mask dimensions to enhance alignment during solder reflow, utilizing surface tension of molten solder.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional solder reflow process is used to attach leads to pads, then the attachment process is simple and efficient, but lead misalignment with pads occurs during soldering

Engineering Contradiction:

Improvelead alignment precisionVSAvoidpad structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The solder mask is pre-applied to the pads before the solder reflow process, creating predetermined alignment features that guide lead placement. This preliminary action establishes the alignment geometry in advance, allowing leads to self-align during soldering without requiring complex real-time adjustment mechanisms

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The solder mask material serves as an intermediary element between the pad and the lead. It provides a physical barrier and alignment reference that mediates the interaction between lead and pad during solder reflow, enabling precise alignment while keeping both the pad and lead structures relatively simple

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If lead alignment construction with solder mask material is implemented, then lead alignment precision is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvelead alignment precisionVSAvoidmanufacturing process ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The solder mask material changes its physical parameters (from solid to liquid to solid) during the solder reflow process. This parameter change allows the mask to initially provide alignment guidance and then flow to accommodate the lead, finally re-solidifying to secure the aligned position, thereby maintaining ease of manufacture through a single reflow process

Inventive Principle:

Principle #35Parameter changes

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

The solution ensures consistent lead placement, reducing misalignment and improving the functionality of device packages by centering leads accurately on pads, thereby enhancing production efficiency and quality.

Implementation Method 1

configuring the pad width and solder mask dimensions to enhance alignment during solder reflow, utilizing surface tension of molten solder

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Data Source

PatentUS20250316565A1Device package having signal pads configured to promote self alignment of leads and process of implementing the same

Publication Date: 2025.10.09 MACOM TECH SOLUTIONS HLDG INC

AI summary

A device package includes a plurality of leads comprising lead structures configured as part of a leadframe during manufacturing. The plurality of leads include attachment pads and a lead alignment construction comprising one or more of the attachment pads being implemented with a solder mask material configured to promote alignment of all of the plurality of leads attached to the leadframe during solder reflow.