Quality control of heavy copper

- Sep 15, 2018-

Chemical Copper Plating, Electroless Plating Copper), commonly known as heavy Copper.The metallization of PCB hole is one of the key technologies of PCB manufacture.Strict control of hole metallization quality is the prerequisite to ensure the final product quality, while the control of heavy copper layer quality is the key.Daily test control methods are as follows:

1.Determination of chemical copper precipitation rate:

Using chemical copper plating solution, there are certain technical requirements for the rate of copper precipitation.If the speed is too slow, it may cause hole or pinhole in the hole wall.The copper deposition rate is too fast, resulting in rough plating.Therefore, the scientific determination of copper sinking rate is one of the means to control the copper sinking quality.Taking the electroless copper plating provided by xianling as an example, the determination method of copper sinking rate is briefly introduced.

(1) materials: epoxy base material after copper etching, with size of 100 x 100(mm).

The sample (2) steps: a. in 120-140 ℃, bake for 1 hour, and then use the analytical balance weight W1 (g);B. in 350-370 g/l chromium anhydride and 208-228 - ml/l sulfuric acid mixture temperature (65 ℃) corrosion in 10 minutes, rinse it.C.In remove chrome waste liquid treatment (30 to 40 ℃ temperature) for 3 to 5 minutes, wash clean;D. Prepreg, activation and treatment in reducing solution as required by process conditions;E. in sink copper liquid temperature (25 ℃) sink copper half an hour, clean;F. specimen in 120-140 ℃, bake for 1 hour to constant weight, weighing W2 (g).

(3) calculation of copper settling rate: rate = (W2-W1) 104/8.10 * 10 * 0 93 x.5 x 2 (microns)

(4) comparison and judgment: compare and judge the measurement results with the data provided by process data.

2.Etching liquid etching rate determination method

Before the through-hole plating, the copper foil was microetched to increase the bonding force with the copper deposit.In order to ensure the stability of etching solution and the evenness of etching on copper foil, the etching rate shall be measured to ensure that it is within the range specified in the process.

(1) materials: 0.3mm copper foil coated board, oil removal, brush board, and cut into 100 x 100(mm);

(2) determination procedure: A.Sample in hydrogen peroxide (80-100 g/l) and sulfuric acid (160-210 g/l), corrosion temperature 30 ℃ for 2 minutes, cleaning, deionized water, clean;B.In 120-140 ℃, bake for 1 hour, constant weight after weighing W2 (g), the sample also according to the conditions of constant weight weighed before corrosion W1 (g).

(3) etching rate calculation rate = (W1-W2) 104/2 times 8.933 t (mu m/min)

Where: s-sample area (cm2) t-etching time (min)

(4) judgment: 1-2 oxidation rate of m/min is appropriate.(1.5-5 minutes copper corrosion 270-540mg).

3.Test method for glass cloth

In the process of hole metallization, activation and copper deposition are the key processes of electroless plating.Although qualitative and quantitative analysis of ionic palladium and reducing solution can reflect the performance of activation reduction, it is not as reliable as the glass cloth test.The condition of copper sinking in glass cloth is the most severe, which can show the properties of activation, reduction and copper sinking liquid.Brief introduction:

(1) materials: the glass cloth is depulp in 10% sodium hydroxide solution.Cut into 50 x 50(mm) and remove some of the glass at the end of the surrounding area, causing the glass to unravel.

(2) test procedure: A.The sample is processed according to the copper sinking process.B. Put the copper sink into the solution. After 10 seconds, the glass cloth should be completely filled with copper, which is black or dark brown.For thick copper, after 10 seconds, the glass cloth end must sink the copper completely. After 30-40 seconds, all the copper will be sunk.C.Judgment: if the above copper sinking effect is achieved, it indicates that the activation, reduction and copper sinking performance are good, while the reverse is poor.