Thin Film Thickness

1. Thin Film Measurement solution Software, sensors, custom development and integration TOUCHSCREEN: EMULSION LAYER MEASUREMENT Touchscreen module manufacturing starts with a wire-grid placed on a conductive polymer. Anti-etch emulsion is deposited on top of the wiregrid. Fig.1. Wire grid with emulsion and subsequent silver paste printing and etching. The thickness of the emulsion needs to be measured for quality control, before the silver paste printing step. The screen is soft and semi-transparent; it requires a non-contact and fast approach for thickness measurement. MProbeHR-MSP systems (700-1100nm wavelength range) is well suited for this application for following reasons: 1.It uses spectroscopic reflectance – a non-contact optical methods 2.Measurement time < 1s (including data analysis) 3.Using 700-1100nm range excludes the effect of the material color (green color in this case) and reduce the effect of light scattering which maybe present at shorted wavelengths 4.Different measurement spot sizes (depending on selected objective) enable to select a proper measurement location. Measurement Summary MProbeHR-MSP system (700-1100nm wavelength range) was used to measure a touch panel sample. The sample was semi-transparent and had an emulsion/polymer deposited on a fine metal grid (290 lines/inch). The thickness of the emulsion/polymer was found to be ~ 15µm. The refractive index of 1.6 was used for the emulsion material. First the measurement was done using ~ 1 mm measurement spot size. It was found that within this area there are several thicknesses: 1.8 µm, 15 µm and 27 µm. The second measurement was done with the smaller spot size ~ 20 µm spot size that was positioned on the emulsion (dark) area. This measurement gave only 15 µm thickness reading. Measurements were done in the central area of the sample. Thick film algorithm (based on FFT) was used to determine the thickness of the films. 83 Pine Hill Rd. Southborough, MA 01772 Phone +1.617.388.6832 Fax. +1.508.858.5473 email: info@semiconsoft.com http://www.semiconsoft.com

2. Fig. 2. Sample from the emulsion side. Fig. 3. Sample under 20x magnification. 83 Pine Hill Rd. Southborough, MA 01772 Phone +1.617.388.6832 Fax. +1.508.858.5473 email: info@semiconsoft.com http://www.semiconsoft.com

3. Table 1. Measurement results Measurement point Point 1 Point 2 Point 3 Point 4 Point 5 * Absolute thickness value of substrate maybe not accurate because substrate refractive index was assumed 1.6 (the real R.I. is different) D Emulsion thickness, µm 15.7 15.3 16.2 14.9 15.2 *Substrate thickness, µm Comment 27.4 26.8 27.8 N/A N/A 1 mm spot 1 mm spot 1 mm spot 20 µm spot 20 µm spot ETAILS. 1.Large spot measurement. Fig.4 Measured reflectance spectrum (point 1) 83 Pine Hill Rd. Southborough, MA 01772 Phone +1.617.388.6832 Fax. +1.508.858.5473 email: info@semiconsoft.com http://www.semiconsoft.com

4. Fig. 5 Point 1 measurement - results of the data analysis. Peaks position correspond to the thicknesses: 1.8 µm (interface), 15.7 µm(emulsion) and 27.4 µm(substrate) 2. Small spot measurement (20 um) Fig. 6. Point 5 (20 µm spot size) reflectance spectrum. 83 Pine Hill Rd. Southborough, MA 01772 Phone +1.617.388.6832 Fax. +1.508.858.5473 email: info@semiconsoft.com http://www.semiconsoft.com

5. Fig. 7. Point 5 (20 µm spot size) measurement results. Peak position correspond to the emulsion film thickness of 15.2 µm 83 Pine Hill Rd. Southborough, MA 01772 Phone +1.617.388.6832 Fax. +1.508.858.5473 email: info@semiconsoft.com http://www.semiconsoft.com