Common problems in FPC circuit design

- Jul 06, 2016-

First, the overlap of the pad

1 pad (except for surface mount solder disc) overlap, which means overlapped holes, in the drilling process of will because in a plurality of drilling result in broken bits, resulting in damaged holes.

2, multilayer plate in the two holes overlap, such as a hole for the isolation plate, the other hole for the connection plate (flower pads), so that the film after the performance of the isolation plate, resulting in scrap.

Two, the abuse of graphic layer

1, in some of the graphics layer to do some useless connections, it is the four board has designed more than five layers of lines, so that misunderstanding.

2, the design graph save trouble, with Protel software as an example of each layer are some line board layer to paint and layer with the board to draw a labeled line, so in Gerber data, because not elected board layer and missed connections and broken, or because the select board layer labeling line short circuit, due to the design keep graphic layer complete and clear.

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

Three, the character of the place

1, the character cover pad SMD welding, to the printed circuit board test and the component of the welding inconvenience.

2, the character design is too small, resulting in the difficulty of screen printing, too assembly to make the characters overlap each other, it is difficult to distinguish.

Four, one side of the disk aperture settings

1, one side pads are generally not drilling, if the drilling need to be marked, the aperture should be designed to zero. If the design values, so in the drilling data, the position appeared hole coordinates, and problems.

2, one side pads such as drilling should be special labeling.

Five, with the filling block painting pad

Filled with a piece of painting pad in the design of the line to the DRC, but for processing is not good, so welding plate is not directly generated resistance welding data, in on the solder resist, the filling block area will be solder resist coverage, which leads to difficulties for welding of the device.

Six, the electrical formation and flower pad is connected

Because the design of the power supply, the formation and the actual printed board on the image is the opposite, all the lines are isolated line, this point designers should be very clear. Here, by the way, several groups of power supply or a few farming isolated line drawing should be careful, not to leave a gap, two groups of power supply circuit, also cannot cause the connection area denial (make a set of power are separated).

Seven, the definition of the level of processing is not clear

1, single panel design in the TOP layer, such as do not add the pros and cons to do, maybe the board is made out of the device and not a good welding.

2, for example, the design of a four TOP mid1, bottom mid2 four, but not in order to place the process, which requires a note.

Eight, the design of the filling block too much or filled with a very fine line

1, resulting in the loss of the phenomenon of light drawing data, the data is not completely painted.

2, because the filling block in the light of the data processing is to use a line to draw a line, so the amount of light generated by the large amount of data, increased the difficulty of data processing.

Nine, surface mount device pad is too short

This is the on-off test, for too dense surface mount devices, the spacing between the feet is quite small, pad quite as fine, needle test installation, must be on (about) the staggered positions, such as the pad design is too short, although does not affect the device installation, but will make wrong needle test on a.

Ten, large area of the grid spacing is too small

A large area of the grid lines between the edges of the line is too small (less than 0.3mm), in the production process of the printed board, the transfer process after the show is easy to produce a lot of broken film attached to the board, resulting in broken.

Eleven, a large area of copper from the frame too close

A large area of copper foil from frame shall ensure at least 0.2mm above spacing, because in milling shape such as milling to copper foil easily lead to copper foil has become warped and caused by the soldermask shedding problem.

Twelve, the outline design of the frame is not clear

Some customers in the layer Board, layer Top, over layer Keep and so on are designed to shape the line and these lines do not coincide, resulting in PCB manufacturers are difficult to determine which line as the standard.

Thirteen, graphics design is not uniform

When the pattern is carried out, the coating is uneven and the quality is affected.

Fourteen the application of the grid line is too large to avoid the foaming of SMT.

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