The problems that occur in PCB proofing are summarized as follows:
1.Hole diameter problem:
General standard circuit board manufacturers, using is automatic CNC drilling equipment, will not deliberately increase a lot of drilling compensation, is according to the principle of finished aperture close to the actual aperture, so many customers in some small sample manufacturers do, will be misleading (many times they directly increase 0.2mm), so that the design did not pay attention to the aperture, mainly manifested in the square connector, the most common problem is 0.6mm pin, think only 0.6mm diameter, aperture according to 0.8mm is enough. In fact, the square component foot, it is required to measure the diagonal dimension, so there is actually more than 0.84mm, so that the manufacturer in the design time must be greater than or equal to 0.85mm, remember!
2.Square groove holes or polygonal holes, grooves
If it is not produced by drilling documents, be sure to be careful not to put the label on other layers of the plate, the safest way is the same plate layer as the frame line (or use multiple drilling holes together)!(For example: protel series, keepout line defines the border line, and the drilling line marked on the mechanical layer is easily ignored); When providing Gerber file, please determine whether two drilling data are exported, which will cause manufacturers to leak one hole and need to delete incomplete drilling data! Manufacturers basic only identify the same frame line polygon slot, please do not put multiple plate layer above, this from the design, also does not conform to the simple is reliable principle, their export Gerber, minutes also missed the plate layer, once appeared, the customer used five mechanical layer to place five different holes.
3.Usage and problems of solder and paste layer:
Anytime, the PCB does not directly use the paste layer, this is used for stencil. If the designer does not need to use this, it is recommended to close it without any reason, which basically does not affect the design, but if the documents provided include the board layer, the manufacturer engineer may use it together with solder, or not superimposed, please note this. In addition, the paste layer will not be used as a resistance welding window. But when using solder to do resistance welding window, remember: if you need to make the disc effect, you must never place the solder data alone.
For example: a tinned line, just with solder draw line, certainly will not make the desired effect.(it may be modified by engineer, but this is the wrong design, and one day it will go wrong).The right way is: first in the line layer after painting the line, and then use solder on the line above the painting line superposition can meet the design requirements!
4.Overhole cover oil:
Perated cover oil is a standard mass production industrial grade design requirements, manufacturers default is cover oil(Regardless of how your files are set up, except for the Gerber files). So if the customer needs to change this default requirement, we need to pay attention to: through the hole does not need to cover the oil, please be sure to explain separately, Gerber files are all produced in accordance with the document, even if the hole description is invalid.
5.Positioning hole electroplating:
In order to facilitate the rapid production of the manufacturer, the sample stage (within 2 square meters is the sample), the manufacturer's default is that the no-copper positioning hole is also done in accordance with the drilling. So if the customer needs to do the sample also do no copper, need to explain to the manufacturer when the order, otherwise the default made of copper hole.
6.Built-in welding pad of mechanical hole:
Most of the time, engineers will use a keepout coil to design an isolated disc, and the problem has misled the manufacturer's engineers to judge. According to the customer definition, the disc (isolated by keepout) may be retained, or drilled according to keepout (computer gong milling hole) (the pad is designed for reference or coordinate positioning, no other purpose), leading to the drilling of mechanical hole, which is 50% error probability. Please design the attention, try to control the simple way, if only need the disc, please finally remove the keepout line; if you need to follow the keepout line opening, please remove the pad.
7.Design issues exceeding the process capability:
Most of the time, the customer design documents, part of the more than the manufacturer's process ability, but the manufacturer in order not to affect the customer delivery period, engineers will modify to the manufacturer's standard range, such as drilling hole diameter is small, the manufacturer modified large, or line width and line distance is small. If possible, the project will be simple processing, may lead to: hole unified cover oil or unified window; line width or line distance is too small or too large, screen text offset and so on, etc., (strongly ask friends to refer to the above process requirements, lest the manufacturer passive modification of the customer confused, but the modified document, electrical function is absolutely correct!）
8.multilayer board inner layer copper shaving
After the multilayer plate slot holes are placed, remember shave copper(Is the corresponding position, the inner layer needs to be separated, with the signal layer will not have this problem)
9.Superconventional design:
Special design, please be sure to explain, sometimes the manufacturer engineers will think the design error, directly correct; for example: tin spray words; pad welding above all or part of the resistance, patch element part of the plate welding, SMT pad with holes, etc., need to simply explain the problems, to avoid the manufacturer engineering as design negligence and modification.
10.Multilayer does not do HASL:
When designing, please pay attention that it looks like the same pad, in fact, it will not be made into the pad, and will be in the top and bottom line, please pay attention!
11.Circuit board appearance:
Designed with Protel99 or Dxp series software, the circuit board shape (e. g., plate frame, slot hole, V-CUT) shall be painted on the Keepout or Mechanical layer. The slotted hole can draw the corresponding shape in the Keepout layer or the Mechanical layer, and it is painted on the same layer as the shape. Note that the Keepout layer or the Mechanical layer can only draw one layer, do not repeat it. The PADS software slot holes are painted on the DrillDrawing layer.
