Electronic Component Package Layout to Prevent Reflow Short Circuits

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Solution Overview

Problem

Electronic component packages with exposed conductive members, such as solder bumps, face short-circuit failures due to remelting during reflow processes when mounted on a different substrate, as the high-melting point alloy phases formed in these packages diffuse and disappear.

Innovation Solution

An electronic component package design where a conductor, made of solder or an alloy between solder and another metal, surrounds the outer circumference of lands on the mounting surface, forming a high-melting point alloy phase that maintains bonding reliability even after reflowing, by using a method involving a dummy substrate for solder application and resin sealing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If exposure parts with high-melting point alloy phases (Sn-Cu) are formed on the mounting surface, then initial bonding reliability is improved, but the alloy phases diffuse and disappear during reflow, causing short-circuit failure

Engineering Contradiction:

Improvebonding reliabilityVSAvoidalloy phase stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the material composition parameters of the exposure parts from conventional Sn-Cu alloy phases to intermetallic compounds with specific stoichiometric ratios (such as Ni3Sn4, Co3Sn4, Pd3Sn4). These intermetallic compounds have significantly higher thermal stability and melting points compared to conventional solder alloys, preventing them from diffusing and disappearing during reflow processes. The specific compositional parameters ensure the exposure parts maintain their structural integrity and bonding functionality through multiple reflow cycles.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite exposure parts consisting of a metal layer (Ni, Co, or Pd) and tin, forming intermetallic compound structures. This composite material approach combines the advantages of different metals: the base metal layer provides thermal stability and structural support, while the tin component ensures good solder wettability and bonding performance. The resulting intermetallic compounds exhibit enhanced thermal resistance and compositional stability during reflow processes.

Inventive Principle:

Principle #40Composite materials

2Reliability

If solder bumps are used as conductive members, then electrical connection is achieved, but remelting during reflow causes solder to flow to adjacent terminals, causing short-circuit failure

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidsolder flow and short-circuit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameters of the conductive members from conventional solder bumps to intermetallic compound-based exposure parts. These intermetallic compounds have melting points significantly higher than conventional solder alloys, preventing remelting during reflow processes. The elevated melting point parameter ensures that the conductive members maintain their shape and position, preventing solder flow to adjacent terminals and avoiding short-circuit failures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of low-melting-point solder material into a benefit by using it as a bonding layer between the intermetallic compound exposure parts and the substrate. The solder layer provides excellent wettability and bonding strength, while the underlying intermetallic compound exposure parts serve as a thermally stable skeleton that prevents remelting and deformation during reflow. This converts the weakness of low-melting-point material into a bonding advantage while the high-melting-point intermetallic structure prevents the harmful effects.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 prevents remelting and short-circuit failures during reflow processes, ensuring reliable bonding of the electronic component package when mounted on a different substrate.

Implementation Method 1

a sealing resin sealing the electronic component

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

a high-melting point alloy phase made of Sn and Cu is formed in each exposure part. This alloy phase diffuses and disappears when the electronic component package is mounted on a different substrate

Methodology Applied

Scientific EffectHigh-melting point alloy phase formation:

Implementation Method 3

a conductor made of solder or an alloy phase between the solder and another metal and surrounding at least a portion of an outer circumference of the land

Methodology Applied

Scientific EffectAlloy phase formation:

Data Source

PatentUS20240312856A1Electronic component package, circuit module and method for producing electronic component package

Publication Date: 2024.09.19 MURATA MFG CO LTD

AI summary

An electronic component package includes an electronic component and a sealing resin sealing the electronic component. In the electronic component package, one of main surfaces of the sealing resin defines a mounting surface used for mounting the electronic component package on a different substrate, and in a view of the mounting surface of the sealing resin, a land electrically connected to an electrode of an electronic component and a conductor made of solder or an alloy phase between the solder and another metal and surrounding at least a portion of an outer circumference of the land are exposed on the mounting surface.