SMT PRINTED CIRCUIT BOARD Reverse Engineering Principle
1 The electronic components placement of SMT PRINTED CIRCUIT BOARD Reverse engineering
1> when SMT PRINTED CIRCUIT BOARD being placed on the convey strap of reflow oven, the longer axis of component should be reverse engineeringed to vertical to the orientation of conveying. Which can prevent the floating or standing of components on the SMT PRINTED CIRCUIT BOARD;
2> components on the SMT PRINTED CIRCUIT BOARD should be reverse engineeringed evenly especially to separate the great power electronic components to avoid the heating trapping on certain point and cause overheating which will affect the soldering point stability directly;
3> With component assembly on both sides, the component with big size should be reverse engineeringed on the different place on both sides otherwise the soldering result will be affected due to the concentration of heating;
4> on the wave soldering side, component with PLCC or QFP footprint should not be reverse engineering SMT PRINTED CIRCUIT BOARD;
5> SMT components on the PRINTED CIRCUIT BOARD wave soldering side should be reverse engineeringed paralleled with direction of wave soldering flow which can greatly decrease the solder bridge between electrical polarity;
6> all the SMT components on the wave soldering flow side shouldn’t be reverse engineering SMT PRINTED CIRCUIT BOARD on the same line, but need to on the separate places to prevent the shadow effect when waving flow to cause the cold soldering or leak soldering.
2 PADs on th SMT Printed circuit board Reverse engineering
1> SMT components on the wave soldering flow side, the bigger size component pad such as triode and sockets are supposed to enlarge, for example, PAD of SOT23 should be enlarged to 0.8-1.0mm, which can avoid the cold soldering due to shadow effect when soldering it;
2> the size of electronic component should be determined by pad, the size of pad equal or a little bit of larger than the electrical polarity size is most fitable when Reverse Engineering PCB.
3> among the two interconnecting components, single big solder pad should be avoided to reverse engineering SMT PRINTED CIRCUIT BOARD since the solder tin on the big pad can draw these components together. The correct way is reverse engineeringing SMT PAD separately and connect the two pads by reverse engineering a thin track among them. If there is higher current required, several parallel tracks should be reverse engineeringed and cover with solder mask.
4> there is no hole or vias on the pad for SMT component, or else in the process of reflow soldering, the solder tin after melted will go through the holes to other side of SMT PRINTED CIRCUIT BOARD which can easier to cause cold soldering, in-surfficient soldering;
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