Semiconductor Substrate Mold Lock Features for Adhesive Bonding
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Solution Overview
Problem
Current high power RF semiconductor packages face reliability issues due to expensive ceramic insulators with poor mechanical tolerances and potential mechanical failures at the polymer/metal interface, especially under new RoHS requirements, and high-temperature polymer materials that limit chip attach options.
Innovation Solution
A semiconductor packaging system with a substrate featuring mold lock features for improved organic adhesive bonding, including protrusions to inhibit crack propagation and moisture ingress, and an alignment feature for enhanced assembly precision, allowing high-temperature chip attach before attaching the electrical insulator structure, which reduces mechanical reliability concerns and supports multiple lead structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic insulators are used in high power RF semiconductor packages, then electrical insulation and RF performance are improved, but cost increases and mechanical tolerances worsen
Solution Approach 1:
The patent changes the material parameter from ceramic to polymer, and changes the joining method parameter from brazing/soldering to mechanical interlocking with mold lock features. This allows achieving adequate electrical insulation with improved mechanical tolerances and lower cost.
Solution Approach 2:
The patent replaces expensive ceramic insulators with cheaper polymer-based electrical insulators that can be molded directly onto the substrate, reducing cost while maintaining functional performance.
2Manufacturing precision
If polymer insulators are used in high power RF semiconductor packages, then cost decreases and mechanical tolerances improve, but reliability at the polymer/metal interface worsens
Solution Approach 1:
The patent incorporates mold lock features into the substrate before attaching the polymer insulator. These pre-formed features create mechanical interlocking that strengthens the bond and prevents interface failure under thermal and mechanical stress.
Solution Approach 2:
The patent creates a composite structure combining the substrate, mold lock features, and polymer insulator into an integrated assembly with improved interfacial strength and reliability.
3Ease of manufacture
If high-temperature polymer materials are used to complete the package before chip attach, then manufacturing integration is improved, but chip attach options are limited due to temperature constraints
Solution Approach 1:
The patent inverts the traditional sequence by allowing high-temperature chip attach to occur first, then attaching the polymer insulator afterward. This reversal enables the use of high-temperature chip attach processes without being constrained by polymer temperature limits.
Solution Approach 2:
The patent segments the manufacturing process into distinct stages: chip attach first, then polymer insulator attachment. This separation allows each process to be optimized independently, enabling high-temperature chip attach followed by lower-temperature polymer processing.
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 provides improved mechanical reliability, reduced costs, and better dimensional tolerances, enabling hermetic enclosures while allowing high-temperature chip attach without degrading the bond between the insulator and substrate, thus addressing the limitations of ceramic and polymer-based packages.
Implementation Method 1
an organic adhesive bond between the substrate and an electrical isolator structure
Implementation Method 2
mold lock features for an adhesive. The mold lock features are a mechanical reinforcement for an organic adhesive bond
Implementation Method 3
protrusions into recesses of the substrate that extend into the organic adhesive and inhibit crack propagation along an interface between the organic adhesive and the substrate
Implementation Method 4
protrusions into recesses of the substrate that extend into the organic adhesive and inhibit crack propagation along an interface between the organic adhesive and the substrate
Data Source
AI summary
A semiconductor structure (100) includes a substrate (110) having a first surface (111) with a mold lock feature (101). The semiconductor structure also includes a semiconductor chip (120) located over the first surface of the substrate. The semiconductor structure further includes an electrical isolator structure (340) located over the first surface of the substrate. The electrical isolator structure includes an electrical lead (341, 342) and an electrically insulative element (343) molded to the electrical lead. An optional portion (444) of the electrical isolator structure is located in the mold lock feature. The semiconductor structure additionally includes an adhesive element (450) located between and coupling the electrical isolator structure and the first surface of the substrate.