Improve Phase Blog

Containment to Prevent Automotive Steering Column Electrical Failures

Improve Phase

Date: 3 April 2016

Introduction 

Due to the failure of our DoE2 samples at Thermal Shock Endurance Testing, it was necessary with immediate effect to come up with an alternative solution to our containment issue. It was proposed as a team that we consult with the supplier of our existing coating material, explain our problem and seek any advice they may have. It was brought to our attention that other customers of theirs had used a new type of material , a Dam and Cure Gel, to help overcome similar issues. This was to be trialled immediately, initially using a hand dispenser as we did not have the correct applicator in our existing conformal coating machine for this material. A revised Gantt Chart was created to schedule all tasks involved in the delivery of the newly proposed process trial.

Revised Gantt Chart

The trials involved three different methods of Dam and Cure Gel application

       1. Hall IC coated with Dam and Cure Gel only

       2. Hall IC coated with Dam and Cure Gel first, then coated with our normal Himiseal UV 40-250

           conformal coating

       3. Hall IC conformal coated with Humiseal UV 40-250 first, then coated with Dam and Cure Gel.

Initial inspection of the hand trials showed a marked improvement in the coverage of the Hall IC's . It was clearly evident that the samples with the Gel placed last gave far superior results as there was complete coverage and better adhesion to the printed circuit board due to it being placed on top of a lower viscosity material. The coverage was put to the test by placing metal debris on top of the coated Hall IC, which was proven to be well protected. These were then sent to our Validations Department for visual inspection and Thermal Shock Endurance Testing.

Metal Debris test on Gel coated Hall IC

Gel location on printed circuit board

When eventually we received the results from the Validations Department, it was worth the wait . All parts had passed validation and we could now progress with automating the process by installing a second Nordson conformal coating machine inline with our existing one. The original machine would not have been capable of applying two different materials. A provisional order has been generated for the new machine at a cost of €76000 and delivery should be in house within two weeks . 

Section of Validation Report for Dam and Cure Gel samples

A layout proposal incorporating the new Nordson Coating machine into the existing line has been generated and plans for actual installation have been drawn up.

Existing Layout Schematic

Proposed Layout Schematic

A risk management plan was put in place to foresee risks, estimate impacts and define responses to issues as a result of the relayout. It also contains a risk assessment matrix. A risk is defines as "in uncertain event or condition that, if it occurs, has a positive or negative effect on a project's objectives. The resultant risk profile is a quantitative analysis of the types of threat the proposed line changes are exposed to.

Risk Assessment Matrix

Process and Equipment Layout Comparison

Risk Profile Evaluation

The Risk profile has been reduced from a rated risk of 69 to 37 through the use of mitigating actions. The Risk Profile is now deemed acceptable by the project team.