DOI: 10.7795/720.20240726
title: Supplemental material to the article "Sub-nm precise measurement of adhesive gaps by imaging interferometry"

description: This dataset contains experimental data from length measurements of adhesive gaps in substrates with and without adhesives at different pressure, temperature, air moisture and time.

The measurements are performed using PTB's Precision Interferometer on a standard material (ULE®) together with a common adhesive (3MTM Scotch-WeldTM DP-460EG), gap thickness approx. 100 µm.

Measurements on the sample without adhesive reveal that the length changes without adhesive are within approx. 0.1 nm under comparable 
conditions. On the adhesive sample, on the other hand, drying in a vacuum and water vapor treatment lead to shrinkage and swelling. These long-term process processes can be described very well by simple but empirical fitting functions. 

The measurement uncertainty budget results in typical values of approx. 0.3 nm for changes of the adhesive gap thickness. This is 
orders of magnitude more accurate than was previously possible using traditional methods on adhesive samples.
description: - block: "sample_01_length change vs pw.csv" 
 research object: Data of Figure 10, Length changes of sample_01 (without adhesive) at varying water vapor pressure (pw). 
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","pw /hPa","temperature / °C","length change / nm" 
 - block: "sample_01_long term length change vs time and temperature.csv" 
 research object: Data of Figure 4, Results of the length measurements on sample_01 (without adhesive) at 20 °C over a period of almost 3 years.. 
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","temperature / °C","length change / nm" 
 - block: "sample_01_long term plate deflections.csv" 
 research object: Data of Figure A1, Long time course of the end plate deflections of sample_01 at 20 °C.
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","temperature / °C","deflection A / nm","deflection B / nm","deflection AB / nm (mean of A and B)" 
 - block: "sample_01_plate deflections vs pw.csv"" 
 research object: Data of Figure A2 - End plate deflections of sample_01 (without adhesive) at varying water vapor pressure. 
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","pw /hPa","T /°C","deflection A / nm","deflection B / nm","deflection AB / nm (mean of A and B)" 
 - block: "sample_05_length change in response to water vapor.csv" 
 research object: Data of Figures 11 and 13 - Swelling of the adhesive gap of sample_05 (3MTM Scotch-WeldTM DP-460EG adhesive) during the one-day exposure to water vapor and subsequent shrinkage. 
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","temperature / °C","pw / hPa","length change / nm","length change at 20°C/ nm " 
 - block: "sample_05_length changes during temperature cycle vs time and temperature.csv" 
 research object: Data of Figures 7 and 8 - Length changes of sample_05 (3MTM Scotch-WeldTM DP-460EG adhesive) during a measurement cycle of approx. 12 days at temperatures from 18°C to 23°C in vacuum excluding data points measured at a temperature drift of more than ±0.1 K/h 
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","temperature / °C","length change / nm","drift-corrected length change / nm" 
 - block: "sample_05_long term length change vs time and temperature.csv" 
 research object: Data of Figures 5 and 14 - Long-term results for sample_05 (3MTM Scotch-WeldTM DP-460EG adhesive) over a period of almost 3 years. These Data exclude the data of length changes during the temperature cycle and length changes in response to water vapor (provided in the separate files mentioned below).
 method: Absolute measuring imaging interferometry 
 format: csv 
 recommended software: Text Editor, Excel etc.
 parameters: "time / days","temperature / °C","length change / nm","length change at 20°C/ nm "