Effective PCB spray tin treatment method

First, the main role of HAL:

1 control surface oxidation of bare copper;

2 maintain weldability;

Second, there are two kinds of spray tin: vertical and horizontal HAL HAL, the main shortcomings of vertical spray tin:

1 uneven heating of the upper and lower assembly, the first in and out, the curl of the easy bending board;

2 The pad thickness is uneven, because the hot air forces and the Chuigua gravity under the edge of the pad production tinplate fell, therefore, SMT solder surface mount components are not easy to paste stability, ease of post-weldment offset or monument legislation phenomenon.

3 The contact time between the board and the wall of the solder is longer. The copper pad is longer than the hole, generally more than 6 seconds. The amount of copper in the furnace is faster than the solder. The increase in the copper content will directly affect the pad due to the resulting thickness of the IMC. The thickness of the alloy layer allows the shelf life of the board shelf to be greatly reduced, significantly overcoming these shortcomings on the level of HAL,

Compared with vertical spray tin, there are the following advantages:

1 The contact time between the molten tin and the bare copper wire is short, about 2 seconds, thin and thin, long shelf life thickness;

2 Wetting time, short wetting time, about 1 second;

3 The board is heated evenly and maintains good mechanical performance.