Terminal Interposer Mold Flow Channels to Prevent Solder Bridging

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Solution Overview

Problem

Existing power amplifier modules face challenges in providing a thermal path for heat dissipation and ground reference when the thermal path needs to extend away from the system PCB, complicating signal, bias voltage, and ground reference provisioning for power transistor dies.

Innovation Solution

The implementation of circuit modules with terminal interposers that include a dielectric body and embedded terminals, featuring mold flow channels to enhance the connection between the terminal interposers and the module substrate, ensuring a robust and solid connection by allowing a thicker encapsulant layer, thus reducing solder bridging and weeping during assembly processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a thicker encapsulant layer is used to connect terminal interposers and module substrate, then connection robustness is improved, but solder bridging and weeping increase during assembly

Engineering Contradiction:
Improveconnection robustnessVSAvoidsolder bridging and weeping
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The patent introduces mold flow channels that divide the encapsulant material into distinct flow paths, segmenting the molding process to control where and how the encapsulant flows during injection. This prevents uncontrolled spreading that causes solder bridging while maintaining adequate encapsulant thickness for robust connections.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the physical state and flow parameters of the encapsulant material by introducing mold flow channels that control viscosity and flow direction during the molding process. This allows the encapsulant to flow in controlled paths rather than spreading uncontrollably, reducing solder bridging while maintaining connection robustness.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If thermal path extends away from system PCB, then thermal management flexibility is improved, but ground reference and signal provisioning complexity increase

Engineering Contradiction:
Improvethermal path configurationVSAvoidsignal and ground reference provisioning
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The terminal interposer acts as an intermediary component between the module substrate and external connections. It provides integrated signal, power, and ground connections while accommodating extended thermal paths, thereby simplifying the overall system complexity despite the flexible thermal management configuration.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The terminal interposer serves multiple functions simultaneously: electrical signal transmission, power delivery, ground reference provision, and thermal conduction. This multi-functionality allows the system to achieve flexible thermal path configuration without proportionally increasing complexity, as a single component handles multiple requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If encapsulant material is applied over terminal interposers, then connection stability is improved, but solder bridging occurs during molding

Engineering Contradiction:
Improveconnection stabilityVSAvoidsolder bridging
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The mold flow channels are pre-formed in the terminal interposer structure before the encapsulant molding process. This preliminary action creates predetermined flow paths that guide the encapsulant material away from solder joints, preventing solder bridging while still allowing the encapsulant to provide stable connections in controlled areas.

Inventive Principle:
Principle #10Preliminary action

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 configuration provides a robust connection between terminal interposers and the module substrate, eliminating or reducing solder bridging and weeping, ensuring reliable signal, bias voltage, and ground reference provisioning for power transistor dies, even when the thermal path extends away from the system PCB.

Implementation Method 1

mold flow channels extending into and/or through the dielectric body. After the terminal interposer is connected to the mounting surface of the module substrate, encapsulant material is applied over at least a portion of the mounting surface of the module substrate. This encapsulant material flows into the mold flow channel(s) of the terminal interposer.

Methodology Applied
Scientific EffectMold flow:

Data Source

PatentEP4485530A1Terminal interposers with mold flow channels, circuit modules including such terminal interposers, and associated methods
Publication Date: 2025.01.01 NXP USA INC
  • EP4485530A1 patent drawingFigure 1
  • EP4485530A1 patent drawingFigure 2~3
  • EP4485530A1 patent drawingFigure 4~5

AI summary

A circuit module includes a module substrate, a terminal interposer, and encapsulant material. The module substrate has a mounting surface and a plurality of conductive pads at the mounting surface. The terminal interposer is coupled to the mounting surface of the module substrate. The terminal interposer includes a dielectric body and a conductive terminal. The dielectric body has top, bottom, and side surfaces, and one or more mold flow channels extending from at least one of the side surfaces into the dielectric body. The conductive terminal is embedded within the dielectric body and extends between the top and bottom surfaces of the dielectric body. A proximal end of the conductive terminal is coupled to a first conductive pad of the plurality of conductive pads. The encapsulant material covers at least a portion of the mounting surface of the module substrate and extends into the one or more mold flow channels.