PCB design in several common questions

A pad of overlap
1, pad (in addition to surface mount pads) will overlap, meaning hole overlap, because the drilling process will result in a broken drill several holes, resulting in damage to the hole.
2, two holes in the plywood overlap, such as a hole for the isolation plate, the other holes for the connection plate (flower pad), so draw the film after the performance of the isolation plate, resulting in scrap.
Second, the graphics layer of the abuse
1, in some graphics to do some useless layer connection, it is a four-layer board is designed for more than five lines, so misleading.
2, design the easy way to Protel software as an example of the layers has a line to draw level with the Board and, with Board level to draw dimension line, so that during the Gerber data, because the Board is not selected layer, missing Connect the circuit, or the Board level will be because the choice of the dimension line and short-circuit, so the graphics layer to maintain the design integrity and clarity.
3, contrary to conventional design, such as surface design in the Bottom layer components, welding face design in the Top, causing inconvenience.
Third, the character of misplacing
1, the character pad SMD lug cover, off to the PCB testing and component welding inconvenience.
2, the character design is too small, resulting in screen printing difficulties, too much can cause the characters overlap, it is difficult to distinguish.
Fourth, the single pad aperture settings
1, single-sided pad is generally not drilling, drilling should be labeled if its diameter should be designed to zero. If the design value, so that drilling in the production data, the location coordinates of the hole appeared, and problems.
2-sided pad, such as drilling should be a special label.
Fifth, fill the block with a painting pad
Fill block with the pad in the design of the line when drawn through a DRC check, but processing is not enough, so the class can not directly generate the solder pad data in the solder resist, the area will be filled block covered by solder mask, resulting in welding devices difficult.
Six electric flower formation is another connection pad
Designed to take the pad because the way the power, ground and the actual image on the printed circuit board opposite, all the connections are isolated lines, which the designer should be very clear. By the way, draw a few sets of power supply or ground line of separation should be careful not to leave gaps, so that two sets of power supply circuit, the connection can not be caused by blockade of the area (to a power supply is separate.)
VII does not explicitly define the processing level
1, single-panel design in the TOP layer, such as the pros and cons of doing without instructions, to come out of the board may be installed on the device and poor welding.
2, for example, a four-layer board design using TOP, mid1, mid2, bottom four, but processing is not placed in this order, which requires description.
Eight, the design of the fill block too much or fill the block filled with a very fine line
1, generate Gerber data have to be lost, Gerber data is incomplete.
2, block by filling in the Gerber data processing is a one to draw the line, the resulting light painted a large amount of data, increased data processing more difficult.
Nine, surface mount device pad is too short
This is off the test run, for very dense surface mount devices, the spacing between its legs rather small, the pad is quite small, installation and testing pin must be up and down (or so) staggered position, such as pad design is too short, although the device does not affect the installation, but will not open the test pin wrong place.
Ten, a large area of ​​the grid spacing is too small
Grid composed of a large area between the edge of the same lines is too small (less than 0.3mm), in the printed circuit board manufacturing process, the map transfer process after the film was finished easily lead to a lot of broken membrane attached to the board, resulting in broken .
XI, away from the frame of a large area of ​​copper foil too close
Large area of ​​copper from the frame above should at least ensure that the spacing of 0.2mm, as a result of milling in the milling time to form on the copper foil warped and likely to cause the solder resist shedding caused by the problem.
XII shape frame design is not clear
Some customers Keepoutlayer, Board layer, Top over layer design of Contour and so they form lines do not coincide, resulting in pcb manufacturer is difficult to judge which of the form line to prevail.
XIII, graphic design uniform
During pattern plating caused by uneven coating, affecting the quality.
XIV shaped element hole is too short
Hole length / width should be ≥ 2:1, the width should be> 1.0mm, otherwise, the Hole in the processing of drilling off easily when drilling, resulting in processing difficulties and increase costs.