Molding Tape Elevated Sidewalls Glob Top Encapsulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional glob top molding processes for IC devices, such as smart cards, face issues with non-uniform size and shape control, incomplete encapsulation, exposed die or wirebonds, and dimensional inaccuracies due to the difficulty in controlling low viscosity resin materials.
Innovation Solution
A molding tape with a die receiving area cut-out and elevated sidewalls is used to adhere to the lead frame, creating a cavity that retains the encapsulant and controls its application, ensuring uniform coverage over the IC die and bond wires while preventing spillage onto the lead frame surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If low viscosity resin material is used for glob top molding, then the encapsulation process is simpler and more automated, but the size and shape control of the glob top becomes poor
Solution Approach 1:
A molding tape with a cavity is introduced as an intermediary tool between the resin dispensing system and the lead frame. The molding tape contains the low viscosity resin material within its cavity during dispensing, preventing spread beyond the desired area. After curing, the molding tape is removed, leaving a precisely shaped glob top. This mediator enables the use of simple low viscosity resin while achieving precise dimensional control.
2Productivity
If low viscosity resin material is dispensed without containment, then the dispensing process is faster and easier, but the resin spreads uncontrollably causing incomplete encapsulation or spillage
Solution Approach 1:
The molding tape is pre-positioned on the lead frame before resin dispensing. The cavity in the molding tape pre-defines the exact area where resin should be deposited. This preliminary action creates a physical boundary that guides the resin flow during rapid dispensing, ensuring the resin fills the cavity completely without spilling outside, thus maintaining both high productivity and precise boundary control.
3Device complexity
If no molding tape is used, then the device structure is simpler, but the glob top dimensions do not conform to package outline specifications
Solution Approach 1:
The molding tape is a disposable, low-cost component that is used once per encapsulation process. It is attached to the lead frame, used to form the glob top, and then removed after curing. This disposable approach provides precise dimensional control during the critical forming stage without requiring complex permanent molding structures, achieving specification conformity with minimal added complexity.
Data Source
AI summary
A lead frame used to assemble a semiconductor device, such as a smart card, has a first major surface including exposed leads and a second major surface including a die receiving area and one or more connection pads surrounding the die receiving area. The connection pads enable electrical connection of an Integrated Circuit (IC) die to the exposed leads. A molding tape sized and shaped like the lead frame is adhered to and covers the second major surface of the lead frame. The molding tape has a die receiving area cut-out that exposes the die receiving area and the connection pads on the second major surface of the lead frame and forms a cavity for receiving an encapsulant. The cut-out has an elevated sidewall for retaining the encapsulant within the cavity.