Komponentin liittäminen venyvälle alustalle puettavan elektroniikan sovelluksissa

Wearable electronics is a new growing field of technology. Many companies have introduced wearable electronics applications, mostly related to the fields of fitness or healthcare. The wearable device should be able to be worn unobtrusively and safely. In order to guarantee those the stretchable electronics may be a more suitable option than conventional rigid electronics or even flexible electronics. One way to implement a stretchable electronics circuit is by miniaturizing functional modules to small rigid functional islands. The islands can be mounted on the stretchable substrate by an adhesive and connected to each other with stretchable interconnects. In this thesis, the aim is to manufacture and evaluate adhesive joints of a different kind between the stretchable substrate and the rigid component. First in this thesis, the theoretical background of the stretchable materials, of the adhesives and of the manufacturing processes is studied. For testing the adhesive joints, the test samples with screen-printed interconnects are manufactured. Then the components are mounted on the substrates by adhesives and the initial electrical properties of the samples are measured. After that the uniaxial cyclic stretch test is implemented where the resistances of the samples are measured continuously using 4-point measurements. The one-time elasticity test is implemented only with the best combination of the adhesive and the substrate. In addition in this thesis, a custom-made test setup is designed and executed which aim is to stretch the sample for the same amount in every direction at the same time. The functionality of the setup is evaluated by comparing it with the other test setup. There were two main quality issues related to the screen-printing process. Firstly, the ink cracked on one substrate and secondly, the impurities weakened the quality of the printed traces. Although the measured sheet resistance values of the ink were higher than in the datasheet of the ink was reported they were still sufficient for this thesis. Only the samples that had all the four measurement channels with an initial resistance lower than 110 Ω were accepted to the strain tests. In addition to the adhesive joint, the measurement included also the resistance of the component and of the small parts of the printed wires. During the strain test, the samples were stretched 10 % for 500 times. The variation between the samples was high, even with the samples with the same combination of the adhesive and the substrate. However, one adhesive performed better than the others. Thus, it was used also in the comparison between the test setups. With the custom-made test setup, the samples lost the connection with a lower uniaxial measured extension, so the setup functioned as expected