Semiconductor Recess Design for Warping Control

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Solution Overview

Problem

Semiconductor devices with flip-chip mounted elements experience warping issues due to thermal expansion differences between the semiconductor element, circuit substrate, and sealing resin, leading to electrical connection defects when mounted on a mother board.

Innovation Solution

A semiconductor device design featuring a recess portion in the sealing resin on the surface opposite to the mounting surface of the semiconductor element, formed by intersecting straight line-shaped grooves with specific dimensions, using a sealing resin with a higher coefficient of thermal expansion than the circuit substrate but lower than the underfill resin, and a glass transition temperature lower than the circuit substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If the whole surface of the sealing resin is ground to reduce device thickness, then the device thickness is reduced, but the sealing resin on the rear surface and surrounding the semiconductor element is reduced, causing warping to persist

Engineering Contradiction:

Improvedevice thicknessVSAvoidwarping stability

Core Design Contradiction:

Length of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent segments the sealing resin into two functional zones: a ground portion (first region) that reduces thickness and a remaining portion (second region) that maintains warping control. The recess portion creates this segmentation, allowing the front surface to be thin while the rear surface retains enough sealing resin to prevent warping.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sealing resin are given different qualities: the first region (front surface) is ground to reduce thickness for mounting requirements, while the second region (rear surface) is preserved to maintain warping control. This local differentiation resolves the contradiction between thickness reduction and warping stability.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the sealing resin is applied by a dispenser to the side surface of the semiconductor element, then the sealing resin can be applied without grinding, but the height or width becomes unstable and production time increases

Engineering Contradiction:

Improvesealing resin applicationVSAvoidsealing resin dimensions

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The sealing resin is applied in advance to cover the entire upper surface of the semiconductor element before mounting. This preliminary application ensures uniform coverage and stable dimensions, avoiding the instability associated with side-surface application during the mounting process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the dispenser application method with a grinding method that uses a precision grinding wheel. This mechanical substitution provides more stable and controllable sealing resin dimensions compared to the dispenser method, while reducing production time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Temperature

If the center of the circuit substrate is mounded upwards under normal temperature or depressed under high temperature due to warping, then thermal expansion differences cause the problem, but electrical connection defects occur when mounted on a mother board

Engineering Contradiction:

Improvethermal expansionVSAvoidelectrical connection

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent changes the physical parameters of the sealing resin, specifically its coefficient of thermal expansion, to match or coordinate with the circuit substrate. This parameter adjustment ensures that thermal expansion and contraction occur uniformly, preventing warping that would cause electrical connection defects during temperature variations.

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

This design effectively reduces warping and associated electrical connection defects by stabilizing the semiconductor device's thickness and weight, enhancing mounting reliability.

Implementation Method 1

using a sealing resin with a higher coefficient of thermal expansion than the circuit substrate but lower than the underfill resin

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the bond is maintained by the contraction of the underfill resin 5

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS8207618B2Semiconductor device and method of manufacturing the same

Publication Date: 2012.06.26 PANASONIC HOLDINGS CORP

AI summary

This semiconductor device is a semiconductor device in which a semiconductor element is flip-chip mounted onto a circuit substrate and the semiconductor element is covered and sealed with a sealing resin. A recess portion is formed in the sealing resin on a surface opposite to the mounting surface of the semiconductor element. Warping of the semiconductor device is reduced by the action of this recess portion.