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Roughness Evaluation of the Inner Lead of a Lead Frame / Surface roughness measurement of a micro area using a laser microscope


A lead frame is an important part that serves as a base for integrated circuit (IC) and large-scale integration (LSI) semiconductor packaging. The frame is a thin layer of metal that supports a semiconductor chip to connect it to outside wiring. The frame is comprised of a die pad that holds the chip, inner lead wires that connect to the chip, and outer lead wires. The inner leads are connected to the chip with gold wiring. The surface of the inner leads must be rough to ensure that the gold wire and inner lead join together adequately. Consequently, checking surface roughness is an important part of quality management.
As semiconductor packages become smaller and denser, the inner leads also become smaller. Manufacturers must employ tools that enable them to measure and evaluate surface roughness in a very small area.

The Olympus solution

Olympus' LEXT 3D scanning laser microscope enables high-resolution surface roughness measurement with a horizontal resolution of 0.12 μm and a step resolution of 5 nm. With traditional contact-type roughness measurement tools, placing the stylus directly on a single ultra-fine lead is very difficult. The OLS4100’s non-contact laser microscope can image an ultra-fine lead for measurement without damaging the sample surface. The microscope’s confocal optical system captures 3D visual data over small steps.

Inner lead


Objective lens 10X

Inner lead in 3D


Objective lens 20X

Surface roughness of the tip of an inner lead


Objective lens 100X, Zoom 2X

Olympus IMS

Products used for this application


With the Olympus LEXT OLS5000 laser scanning confocal microscope, noncontact, nondestructive 3D observations and measurements are easy to produce. Simply by pushing the Start button, users can measure fine shapes at the submicron level. Ease of use is combined with leading-edge features to deliver an acquisition speed four times faster than our previous model. For customers with larger samples, LEXT long working distance objectives and an extended frame option allow the system to accommodate samples as large as 210 mm.
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