IPC-TM-650,2,5,7,1

1 Scope The dielectric withstanding voltage test (also called high-potential, over potential or voltage breakdown test) consists of the application of a voltage higher than rated volt- age for a specific time between mutually isolated portions of a PWB or between isolated portions and ground. This is used to prove that the PWB can operate safely at its rated voltage and withstand momentary over potentials due to switching, surges, and other similar phenomena. Although this test is often called a voltage breakdown test, it is not intended that this test cause insulation breakdown or to be used for detect- ing corona. Rather, it serves to determine whether insulating materials and/or conductor spacings are adequate. 2 Applicable Documents IPC-CC-830 Qualification and Performance of Electrical Insu- lating Compound for Printed Board Assemblies IPC-A-600 Acceptability of Printed Wiring Boards MIL-STD-202 Method 301 J-STD-004 Requirements for Soldering Fluxes 3 Test Specimens 3.1 Qualification Testing, Classes 1-3 Five IPC-B-25A boards (see Figure 1) using the D comb pattern (one uncoated and four coated) with conformal coating according to the coating suppliers recommendations. 3.2 Conformance Testing Five IPC-B-25A Boards (See Figure 1) containing the C pattern (‘‘Y’’ shape pattern) with 0.635 mm lines/0.635 mm spacing [25.00 mil lines/25.00 mil spacing] or minimum spacing on the production board, whichever is smaller, coated with conformal coating according to the coating supplier’s recommendations. 4 Apparatus 4.1 Soldering Iron 4.2 Flux Water white rosin (R or RMA) with halide content less than 0.5%, i.e., type Symbol A and B or ROL0 and ROL1 according to J-STD-004. 4.3 Hi-Pot Tester Capable of supplying a test voltage of 1,500 VAC at 50-60 hertz (Hz) and able to record a leakage rate. 4.4 Timer 4.5 Oven Capable of maintaining 60°C [140°F]. 4.6 Desiccator 5 Test Specimens Preparation Prior to Testing 5.1 Solder wires to the finger tabs on the ‘‘D’’ comb pattern using R or RMA flux. 5.1.1 Clean the specimens using a soft bristle brush while rinsing with deionized water for 30 seconds. IPC-2571-1 Figure 1 IPC-B-25A Test Board (Leads on D Pattern Are Identified) 2215 Sanders Road Northbrook, IL 60062-6135 IPC-TM-650 TEST METHODS MANUAL Number 2.5.7.1 (Supersedes 2.5.7C for Conformal Coating Test) Subject Dielectric Withstanding Voltage - Polymeric Conformal Coating Date 07/00 Revision Originating Task Group Conformal Coating Task Group (5-33a) Material in this Test Methods Manual was voluntarily established by Technical Committees of IPC. This material is advisory only and its use or adaptation is entirely voluntary. IPC disclaims all liability of any kind as to the use, application, or adaptation of this material. Users are also wholly responsible for protecting themselves against all claims or liabilities for patent infringement. Equipment referenced is for the convenience of the user and does not imply endorsement by IPC. Page 1 of 2 ASSOCIATION CONNECTING ELECTRONICS INDUSTRIES 5.1.2 Immerse and agitate the test specimens in 2-propanol for 30 seconds. Scrub with a soft bristle brush and spray with clean 2-propanol. 5.1.3 Place the cleaned specimens in an oven maintained at 50°C [122°F] for three to five hours to dry. 5.1.4 Remove the specimens from the oven and place in a desiccator to cool. 5.1.5 Conformal coat the test specimens and cure in accor- dance with the suppliers recommendations. If the specimens are not used immediately, seal the specimens in Kapac® bags. 5.2 Procedure 5.2.1 For each individual specimen, secure all the positive leads (1, 3 and 5) together and the negative (2 and 4) together. 5.2.2 Attach the leads of the Hi-Pot Tester to the wires of the test specimen. 5.2.3 Raise the test voltage from zero to 1,500 VAC at 100 VAC per second. 5.2.4 Apply the test voltage of 1,500 VAC at 50-60 Hz for one minute and record any leakage rate. 5.2.5 After the one-minute duration, turn off the voltage and disconnect the test specimen from the Hi-Pot Tester. 6.0 Evaluate 6.1 Record if the specimen exhibits flashover, sparkover or breakdown. 6.1.1 Record the leakage current of each specimen. IPC-TM-650 Number 2.5.7.1 Subject Dielectric Withstanding Voltage - Polymeric Conformal Coating Date 07/00 Revision Page 2 of 2