Quality inspection method for electroplated prepreg PCB circuit boards

Quality inspection method for electroplated prepreg PCB circuit boards

Pre impregnated material is a sheet-like material composed of resin and carrier. The resin is in the B-stage, and under the action of temperature and pressure, it has fluidity and can quickly cure and complete the bonding process, forming an insulation layer together with the carrier. Commonly known as semi cured sheet or adhesive sheet. To ensure the high reliability and quality stability of multi-layer printed circuit boards, it is necessary to conduct quality testing (trial lamination method) on the characteristics of the semiconductor chips. The characteristics of electroplated semi cured circuit boards include two parts: pre lamination characteristics and post lamination characteristics. The characteristics before lamination mainly refer to: resin content%, fluidity%, volatile content% and gel time (S). The characteristics after lamination refer to electrical performance, thermal shock resistance, and flammability. Therefore, in order to ensure the high reliability of multi-layer printed circuit boards and the stability of laminating process parameters, it is very important to test the characteristics of the electroplated semi cured film of the circuit board before lamination.

1. Determination of resin content (%) in circuit boards:

(1) Preparation of test pieces: Cut 100 × 100 (mm) small test pieces at a 45 ° angle according to the fiber direction of the electroplated semi cured sheet on the circuit board;

(2) Weighing: Use a balance with an accuracy of 0.001 grams to weigh Wl (grams);

(3) Heating: Heat and burn at a temperature of 566.14 ℃ for 60 minutes, then weigh W2 (grams) after cooling;

(4) Calculation: W1-W2 resin content (%)=(W1-W2)/W1 × 1002.

2. Determination of resin flow rate (%) on circuit board:

(1) Preparation of test pieces: Cut several pieces of approximately 20 grams, each measuring 100 × 100 (mm), at a 45 ° angle according to the direction of the electroplated semi cured fibers on the circuit board;

(2) Weighing: Use a balance with an accuracy of 0.001 grams to accurately weigh W1 (grams);

(3) Heating and pressurization: Adjust the temperature of the heating plate of the press bed to 171 ± 3 ℃. When the test piece is placed in the heating plate, apply a pressure of 14 ± 2Kg/cm2 or more, heat and pressurize for 5 minutes, cut off the flowing adhesive and weigh W2 (grams);

(4) Calculation: Resin flow rate (%)=(W1-W2)/W1 × 1003.

3. Gel time measurement of circuit board:

(1) Test piece production: Cut the semi cured film fiber direction of the circuit board electroplating into several pieces of 50 × 50 (mm) at a 45 ° angle (each piece weighing about 15 grams);

(2) Heating and pressurization: Adjust the temperature of the heating plate to 171 ± 3 ℃ and the pressure to 35Kg/cm2 for 15 seconds;

(3) Measurement: The test piece is measured from the start time of pressurization to the curing time.

4. Determination of volatile matter content in circuit boards:

(1) Test piece production: Cut 1 piece of 100 × 100 (mm) at a 45 ° angle according to the fiber direction of the electroplated semi cured sheet on the circuit board;

(2) Weighing: Use a balance with an accuracy of 0.001 grams to weigh W1 (grams);

(3) Heating: Use an air circulation constant temperature bath to heat at 163 ± 3 ℃ for 15 minutes, and then weigh W2 (grams) with a balance;

(4) Calculation: Volatile matter (%)=(W1-W2)/W1 × 100.