Common problems in the design of FPC circuits

- Sep 08, 2017-

One, Overlap of pads

1, the pad (except surface welded plate) overlap that hole overlap in the drilling process because many drilling in a drill hole lead to broken, leading to injury.

2, the multi plate in the two holes overlap, such as a hole position for the separation disk, and the other hole for the connection plate, so painted negative after showing the separation disk, resulting in scrap.

Two, the abuse of graphic layer

1, in some graphics layer made some useless connection, originally is four boards have designed more than five lines, make misunderstanding.

2, the design plan, for example with Protel software on each layer by layer to draw some lines of Board, and using Board layer to draw line, so in light painting data, because no Board layer, missing connection circuit, or because the Board layer line and short-circuit. Because of the design of graphic layer keep complete and clear.

3, contrary to conventional design, such as component surface design in the Bottom layer, welding surface design in Top, causing inconvenience.

Three, the character of the place

1, character cover, welding disc, SMD welding piece, inconvenience to PCB's breaking test and component welding.

2, character design is too small, resulting in screen printing difficulties, too general to overlap each other characters, it is difficult to distinguish.

Four,the setting of the hole diameter of the single pad

1, the single pad generally does not drill holes, if the drilling needs to be marked, the aperture should be designed to zero. If a value is designed, the coordinates of the hole appear when the drill data is generated, and problems arise.

2, single pad, such as drilling should be marked.

Five. Fill the block with a paint pad

Filling blocks for painting pad in the design of the line can be checked by DRC, but for processing is not enough, so the class pads directly generate resistance welding data can not, in the solder, the solder resist filling block area will be covered, resulting in difficult welding device.

Six. The electric layer is a flower pad and a connecting line

Because of the power that is designed as a flower pad, the formation is opposite to the image on the actual printed board, and all the wires are isolated lines, which the designer should be very clear about. Here, by the way, you should be careful when you draw a few sets of power or a few lines of isolation. You can't leave a gap between the two sets of power supplies, and the area of the connection is not blocked (so that a set of power supplies are separated).

Seven, the processing level definition is not clear

1, the single panel design in the TOP layer, such as without explanation, positive and negative do, may be made out of the board mounted device, and not good welding.

2, for example, a four board design using TOP, mid1, mid2, bottom four layers, but the processing is not placed in this order, which requires instructions.

Eight, design too many filling blocks or filling blocks filled with very fine lines

1, the rendering of data is lost, rendering data incomplete.

2, because the filling block is painted in the data processing, it is drawn with lines one by one, so the amount of data generated by drawing is quite large, which increases the difficulty of data processing.

Nine ,surface mount device pads are too short

This is the on-off test, for the surface mount device too dense, the distance between the feet is quite small, the pad is quite fine, install the test needle, must be under the staggered position (left and right), such as the pad design is too short, although does not affect the device installation, but will make the wrong needle test don't open position.

Ten, large spacing of the grid is too small

The edge of a large area grid line is too small (less than 0.3mm). In the process of manufacturing the printed circuit board, it is easy to produce a lot of broken film attached to the board, resulting in broken wires after the completion of the printing process.

Eleven, Large area copper foil is too close to outer frame

Large area copper foil spacing frame should ensure at least 0.2mm of the above spacing, because in milling form, such as milling copper foil, easy to cause copper foil curling and caused by the solder drop problem.

Twelve, the shape of the border design is not clear

Some customers in the Keep, layer, Board, layer, Top, over, layer and other designed contour lines, and these contour lines do not coincide, causing PCB manufacturers it is difficult to determine which contour line prevail.

Thirteen, uneven graphic design

When the pattern is electroplated, the coating is uneven and the quality is affected.

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