Transistor Outline Package Thickened Metal Cap Welding

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Solution Overview

Problem

Existing TO packages face challenges in welding optical sub-assemblies due to stress introduction and risk of perforation, especially with thin metal caps, which affects hermetic sealing and compatibility with standard designs, and introduces dimensional and positional tolerances.

Innovation Solution

A TO package design with a metal cap featuring a thickened lateral or end wall portion for increased mechanical stability, allowing for secure welding of a metal optical sub-assembly without risking perforation, while maintaining compatibility with standard designs through a stepped wall thickness transition and reduced heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the wall thickness of the metal cap is increased to prevent perforation during welding, then the mechanical stability and hermetic sealing are improved, but the geometry of the housing changes so that it no longer corresponds to standard type housings

Engineering Contradiction:

Improvehermetic sealingVSAvoidcompatibility with standard designs

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The metal cap is designed with non-uniform wall thickness, featuring a thickened portion at the base and a thinner lateral wall portion. This local differentiation allows the base to withstand welding stresses and maintain hermetic sealing, while the thinner lateral walls preserve the standard housing geometry for compatibility with existing designs and mounting structures.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If laser welding is used to connect the optical sub-assembly, then the manufacturing precision and automation are improved, but stresses are introduced into the housing material causing geometric changes and risk of perforation

Engineering Contradiction:

Improvealignment precisionVSAvoidstress-induced geometric changes

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The metal cap is designed with a thickened base portion before the welding process, providing a stress buffer zone that absorbs welding-induced thermal stresses. This preemptive structural reinforcement prevents stress propagation to the thinner lateral walls, avoiding geometric changes and perforation risks during laser welding operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If an adapter ring is welded to the header to enable optical sub-assembly connection, then the adaptability is improved, but the device complexity and manufacturing precision requirements increase due to additional components and tolerances

Engineering Contradiction:

Improvewelding capabilityVSAvoidnumber of components

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The welding interface for the optical sub-assembly is integrated directly into the metal cap structure through the thickened base portion, eliminating the need for a separate adapter ring. This merging of functions reduces the total component count, simplifies the assembly structure, and decreases the accumulation of dimensional and positional tolerances that would arise from additional intermediate components.

Inventive Principle:

Principle #5Merging (Combining)

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 design enhances mechanical stability, reduces stress-induced geometric changes, and improves heat transfer, enabling reliable and precise alignment of optical components without compromising hermetic sealing or design compatibility.

Implementation Method 1

the thickened lateral or end wall portion for increased mechanical stability, allowing for secure welding of a metal optical sub-assembly without risking perforation, while maintaining compatibility with standard designs through a stepped wall thickness transition and reduced heat transfer

Methodology Applied

Scientific EffectStress distribution:

Implementation Method 2

maintaining compatibility with standard designs through a stepped wall thickness transition and reduced heat transfer

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 3

stresses are introduced into the housing material by the welding, in particular by laser welding

Methodology Applied

Scientific EffectLaser welding: Laser Beam Welding

Data Source

PatentUS10908371B2Transistor outline package and method for producing a transistor outline package

Publication Date: 2021.02.02 SCHOTT AG

AI summary

A transistor outline (TO) package including a header with at least one optoelectronic device. The header is bonded to a pot-shaped metal cap, which has a window that is transmissive to electromagnetic radiation, such that the at least one optoelectronic device is arranged in a hermetically sealed interior. The wall of the metal cap has at least one lateral wall portion and/or end wall portion which is thickened towards the interior compared to a portion of the lateral wall of the metal cap adjacent to the header.