Semiconductor LDS Packaging with Fiducial Alignment Through Mold Compound
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Solution Overview
Problem
Conventional laser direct structuring (LDS) in semiconductor manufacturing is performed as a 'blind' process due to the light-impermeable LDS compound masking the semiconductor chips, leading to misalignment and low yield, especially for devices with small pads, and requires additional strip mapping and AOI, increasing time and cost.
Innovation Solution
Employing laser-induced forward transfer (LIFT) to create markers (fiducials) on semiconductor dice, which are optically detectable through the LDS material, allowing precise laser beam processing to form electrically conductive formations without modifying the dice structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDS compound is molded onto the leadframe to encapsulate semiconductor chips, then electrical connections can be provided via laser direct structuring, but the light-impermeable LDS compound masks the chips making alignment impossible
Solution Approach 1:
Markers are formed on the semiconductor chips before the LDS compound is molded onto the leadframe. This preliminary action ensures that reference points are available before encapsulation, enabling precise alignment during subsequent laser direct structuring despite the light-impermeable nature of the LDS compound.
Solution Approach 2:
Markers serve as intermediary reference points that bridge the gap between the chip positions and the laser direct structuring process. These markers remain visible through the LDS compound or are positioned such that they provide alignment references without being obscured by the encapsulating material.
2Measurement precision
If strip mapping and AOI equipment are used to detect chip positions, then alignment information can be obtained, but assembly time and cost increase
Solution Approach 1:
The semiconductor chips themselves provide the alignment information through markers that are formed as part of the chip structure. This eliminates the need for separate AOI equipment and strip mapping processes, as the chips self-identify their positions and orientations through the embedded markers.
Solution Approach 2:
The alignment detection function is extracted from external AOI equipment and integrated directly into the chip structure through markers. This removes the need for separate measurement devices and processes, streamlining the assembly flow.
3Adaptability or versatility
If conventional wire bonding is used to provide electrical connections, then reliable connections can be established, but the process is replaced by LDS technology requiring new alignment methods
Solution Approach 1:
The invention adapts the alignment approach from conventional wire bonding to LDS technology by introducing markers that are specifically designed for optical detection. These markers enable the laser direct structuring process to achieve the precision needed for modern semiconductor interconnection, matching or exceeding conventional wire bonding accuracy.
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
Facilitates accurate alignment and reduces misalignment issues, enhancing yield and reducing assembly time and cost by enabling precise laser structuring directly on the semiconductor devices.
Implementation Method 1
applying laser-induced forward transfer (LIFT) processing to the at least one semiconductor die to form at least one marker on the second surface of the at least one semiconductor die
Implementation Method 2
laser beam processing the laser direct structuring material molded onto the substrate having at least one semiconductor die arranged thereon to provide electrically conductive formations therein. The laser beam processing of the laser direct structuring material comprises applying laser beam energy to the surface of the laser direct structuring material
Data Source
AI summary
One or more semiconductor dice are arranged on a substrate. The semiconductor die or dice have a first surface adjacent the substrate and a second surface facing away from the substrate. Laser-induced forward transfer (LIFT) processing is applied to the semiconductor die or dice to form fiducial markers on the second surface of the semiconductor die or dice. Laser direct structuring (LDS) material is molded onto the substrate. The fiducial markers on the second surface of the semiconductor die or dice are optically detectable at the surface of the LDS material. Laser beam processing is applied to the molded LDS material at spatial positions located as a function of the optically detected fiducial markers to provide electrically conductive formations for the semiconductor die or dice.