BIO Study And Improvement For Two-Way Portable Radio LCD

摘要

Motorola two-way radios are famous for their robust design. All the portable radios are required to pass stringent Motorola internal reliability test which include drop test, ball impact drop and environmental test. According to the quality requirements, during and after these tests the LCD should not lose functionality. The LCD glass must also meet strain of >= 0.16% based on the simulation result of ball impact test. Initially, Product B LCD could not achieve B10 of 0.16% strain. In this paper, a systematic methodology which was used to resolve B10 issues is presented. B10 is a value that describes the strain level that 10 percent of the displays are expected to break. Simulation had been used to predict the robustness of the module and the failure criteria predicted using Motorola 4 points bend test specification which outlines the details of strain experiment. Based on fishbone diagram analysis, material was a main contributor factor, thus soda lime glass has been changed to tempered glass. Besides that, the display sealant width has also been increased from 0.28 mm to 0.32 mm to achieve a better bonding strength between top and bottom glass and the LC filling baffle has also been moved from middle to the top and bottom corners to avoid the poor glass edge quality issue. Finally these improvements allowed Product B LCD to meet the requirement of minimum 0.16% strain. This paper allows the team to be aware and appreciate factors that affect the B10 of LCD glass. It can be a good reference for engineers who design LCD that are required to meet high robustness requirements expected in portable two-way radios.