PREFERENTIAL ETCH OF GALVANIC TIN-AND-LEADEN OF COATINGS FROM COPPER BASIS Russian patent published in 2009 - IPC C23F1/30 

FIELD: metallurgy.

SUBSTANCE: invention relates to chemical metal treatment technology and can be used during the manufacturing of double-ended printed circuit board with blocking soldering mask for copper. Preferential etch of galvanic tin-and-leaden coatings from copper basis contains following components: fluoboric acid (40%-solution) 950.0 - 970.0 ml/l, hydrogen peroxide (35%-solution) 30.0 - 50.0 ml/l, copper nitrate (II) 0.03 - 0.04 g/l, potassium fluoride 5.0 - 8.0 g/l, sodium nitrate 5.5 - 7.5 g/l. While usage of proposed etchant etching rate of alloy tin-and-leaden more than ten times increases etching rate of copper basis.

EFFECT: decrease of destruction risk of metallisation in holes of printed circuit card and increasing of yield ratio at production of electronic products.

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