Dual-Side Molded Package Substrate for Heat Dissipation and Warpage

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Solution Overview

Problem

Transitioning FCBGA packages from Ajinomoto build-up film (ABF) to prepreg dielectric materials for larger body sizes presents assembly manufacturing yield and thermal performance challenges, including warpage and insufficient thermal dissipation in conventional FCCSP solutions.

Innovation Solution

A dual side molded package substrate with no solder mask, featuring first and second molded package structures made of high thermal conductivity epoxy molding compound, attached to a multilevel package substrate with semiconductor die, providing improved thermal performance and reduced warpage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If FCBGA packages transition from ABF to prepreg dielectric materials for larger body sizes, then manufacturing cost is reduced, but thermal performance deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidthermal performance

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent uses a composite material structure combining prepreg dielectric layers with high thermal conductivity epoxy molding compound (EMC) having thermal conductivity of 3-10 W/mK. This composite approach allows the package to maintain the cost benefits of prepreg materials while incorporating thermally conductive EMC to improve heat dissipation performance, thereby resolving the contradiction between manufacturing cost and thermal performance.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If conventional FCCSP solutions are used for larger body sizes, then cost is reduced, but warpage increases during manufacturing

Engineering Contradiction:

Improvemanufacturing costVSAvoidsubstrate warpage

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material parameters by selecting prepreg dielectric materials and epoxy molding compounds with matched thermal expansion coefficients and controlled moisture content. This parameter optimization reduces differential stress during temperature cycling and manufacturing processes, thereby minimizing substrate warpage while maintaining the cost advantages of prepreg-based FCCSP structures.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If ABF substrate material is used for larger body sizes, then thermal performance is maintained, but manufacturing cost increases

Engineering Contradiction:

Improvethermal performanceVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies local quality by using standard cost-effective prepreg dielectric materials for the substrate layers while concentrating high thermal conductivity EMC specifically in the molded package structures that directly contact and encapsulate the semiconductor die. This localized application of high-performance thermal material maximizes heat dissipation where it is most needed while minimizing overall material costs.

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If solder mask is applied to package substrate, then manufacturing process is complete, but additional processing steps and cost are added

Engineering Contradiction:

Improveprocess completionVSAvoidprocessing steps

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the functions of the molding compound and traditional solder mask by using the epoxy molding compound to provide both package encapsulation and surface protection functions. The EMC is applied during the molding process to form a continuous protective layer over the conductive features, eliminating the need for separate solder mask application, patterning, and curing steps, thereby reducing device complexity and processing steps.

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 solution enhances thermal conductivity by 1.8-8.4%, reduces substrate warpage by up to 85%, and lowers manufacturing costs by eliminating solder mask processing steps, while maintaining high I/O density interconnection.

Implementation Method 1

a first molded package structure on the first side and a second molded package structure on the second side and spaced apart from the first molded package structure

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS20250273535A1Electronic device dual side molded soldermaskless package substrate package for improved thermal dissipation and thermomechanical integrity

Publication Date: 2025.08.28 TEXAS INSTRUMENTS INC

AI summary

An electronic device includes a multilevel package substrate having opposite first and second sides, a semiconductor die attached to the first side, a first molded package structure on the first side, and a second molded package structure on the second side and spaced apart from the first molded package structure. A method of fabricating an electronic device includes attaching a semiconductor die to a first side of a soldermaskless multilevel package substrate, forming a first molded package structure on the first side of the multilevel package substrate, and forming a second molded package structure on an opposite second side of the multilevel package substrate and spaced apart from the first molded package structure.