Leadframe Heat Sink Assembly for Uniform Bond Line Thickness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing lead-less surface mount semiconductor devices is achieving accurate control of adhesive bond thickness for top and bottom side exposed heat sinks, which is crucial for effective thermal dissipation, as variations in bond line thickness can lead to tilted heatsinks and reduced thermal dissipation due to moulding compound flashes.
Innovation Solution
The semiconductor device features L-shaped lead frames with exposed heat sinks on both sides, integrated external contact portions, and consistent conductive adhesive layers to ensure accurate bonding and thermal dissipation, while allowing for electrical connection to a carrier, with a method involving precise dispensing and encapsulation to maintain bond line thickness consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If adhesive bond thickness is not accurately controlled, then manufacturing process is simpler, but heatsink tilting occurs and thermal dissipation is reduced
Solution Approach 1:
The patent applies preliminary action by providing recesses in the heatsink structure before adhesive bonding. These recesses are pre-configured to accommodate the adhesive layer, ensuring that the adhesive is contained within specific boundaries. This preliminary structural preparation enables consistent bond line thickness without requiring complex real-time control during the bonding process, thus resolving the contradiction between manufacturing precision and ease of manufacture
Solution Approach 2:
The patent changes the geometric parameters of the heatsink by introducing recesses with specific dimensions. The recess depth and width are carefully designed to match the adhesive layer thickness, transforming the bonding interface geometry. This parameter change ensures that the adhesive forms a uniform layer, achieving consistent bond line thickness through structural design rather than process control, thereby resolving the contradiction
2Reliability
If heatsink is tilted due to bond thickness variation, then adhesive application is easier, but moulding compound flashes occur and thermal dissipation is reduced
Solution Approach 1:
The recesses are pre-formed in the heatsink structure to provide physical boundaries for the adhesive layer. This preliminary action ensures that the adhesive remains confined and maintains uniform thickness, preventing heatsink tilting during bonding. The pre-configured geometry directly prevents alignment errors, thus improving both reliability and manufacturing precision simultaneously
Solution Approach 2:
The adhesive layer acts as a thin film that is contained within the recess boundaries. This thin film approach, combined with the recess structure, ensures uniform distribution of the adhesive without requiring high precision in the bonding process itself, thereby preventing tilting and maintaining thermal dissipation effectiveness
3Temperature
If exposed heat sinks are implemented, then thermal dissipation is improved, but manufacturing complexity increases due to bonding control requirements
Solution Approach 1:
The recesses are pre-configured in the heatsink structure to define the adhesive bonding interface. This preliminary geometric preparation simplifies the bonding process by providing natural boundaries for the adhesive, eliminating the need for complex bonding control systems. The exposed heat sink structure is maintained while the bonding complexity is reduced through this pre-configuration approach
Solution Approach 2:
The heatsink structure is segmented with recesses that create distinct zones for adhesive placement. This segmentation approach allows the exposed portions of the heatsink to maintain thermal dissipation functionality while the recessed portions provide controlled bonding areas, thereby achieving both thermal performance and manufacturing simplicity
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 enhances thermal dissipation and maintains consistent bond line thickness, preventing tilting and moulding compound coverage issues, thereby improving the robustness and efficiency of heat dissipation in semiconductor devices.
Implementation Method 1
A first layer of conductive adhesive may be arranged between the first contact terminal and the first major surface of the first lead frame; and a second layer of conductive adhesive may be arranged between the second contact terminal and the first major surface of the second lead frame
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3e
AI summary
This disclosure relates to a semiconductor device and method of manufacture, comprising: a semiconductor die wherein the semiconductor die comprises a first major surface having a first contact terminal arranged thereon and an opposing second major having a second contact terminal arranged thereon; a first lead frame having first and second opposing major surfaces wherein the first major surface is fixedly attached to the first contact terminal of the semiconductor die; a second lead frame having first and second opposing major surfaces wherein the first major surface is fixedly attached to the second contact terminal of the semiconductor die; and wherein the first lead frame comprises an integrally formed external contact portion extending from the first major surface thereof to a plane substantially co-planar with the second major surface of the second leadframe.