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Surface Roughness Measurement of Flexible Print Substrate using the Olympus OLS4100 Laser Confocal Microscope


As electronics become smaller and more sophisticated, the demand for miniaturized flexible printed boards continues to grow. In order to make a flexible printed board, one or more copper foil layers are attached to a dielectric resin substrate. The copper foil is then etched to create the desired wire patterns. Before being applied to the substrate, the copper surface is roughened to promote adhesion. If the copper surface does not have sufficient roughness, it will not hold to the resin strongly enough to survive the rigors of the manufacturing process. This leads to defects and the failure of electronic devices. Consequently, the roughness of copper foil must be carefully measured.

The Olympus solutions

The Olympus OLS4100 3D laser measurement microscope is capable of measuring surface roughness with plane and unevenness resolutions of 0.12 μm and 5 nm, respectively. The microscope has an ultra-high pixel density so that even subtle surface unevenness is accurately measured. Since the OLS4100 uses non-contact roughness measurement, the soft copper film will not be damaged. 

Features of the product

The Olympus OLS4100 gives you the ability to make 3D observations with ultra-high-resolution and a high pixel density. The microscope has high inclination sensitivity enabling it to make accurate measurements of complex geometric structures with steep sides. The non-contact roughness measurement feature ensures that sensitive copper surfaces are measured without damage.


A high-resolution image and 3D model of a copper surface

Figure 1: A high-resolution image and 3D model of a copper surface

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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