PCB layout Parameters

Address: http://blog.csdn.net/devincoder/article/details/6598052

 

The final purpose of PCB layout is to produce applications. When it becomes a formal and valid product, layout's work is regarded as a paragraph. In layout, which common key points should be paid attention to so that the files drawn by myself can effectively comply with the general PCB processing factory rules, so as not to cause unnecessary additional expenses to enterprises?

Based on my years of practical experience and continuous improvement in PCB production technology, I have concluded that the current PCB layout generally follows seven rules:

I. Drilling Design Rules

(1) PCB Board works in principle to design an 8-shaped hole into a groove hole (annular hole ). Therefore, we recommend that you create a ring as much as possible during layout. If you do not have this function, you can place n circles and fold as many as possible. In this way, the Ring Groove won't show "dogs need teeth", and the board manufacturer won't break the drill bit because of your slot hole!

(2) The minimum pore size for mechanical drilling is 0.25mm (10mil). Generally, the aperture design is greater than or equal to 0.3mm (12mil ). If it is smaller than this, it is just 0. 25mm, the people in the board factory will definitely look for you. Why? Find the answer in (5!

(3) The minimum slot hole diameter is 0.25mm (10mil). Generally, the aperture design is greater than or equal to 0.3mm (12mil ). Same as (2 ).

(4) In general practice, only the unit of mechanical drilling is mm, and the remaining unit is mil. The habit of drawing is that in addition to the library, we need to use mm for the volume and size, while the rest use mil for the Unit. The Unit of mil is small, which is really convenient.

(5) generally, the aperture of the laser drilling (laser) is 4mil (0.1mm)-8mil (0.2mm ). Generally, more than 6 layers, and very intensive board, will use this technology, such as mobile phone motherboard, of course, the price will certainly increase by N levels. More importantly, the minimum PCB processing elements: one to three blind buried holes, minimum Laser (laser) drilling 4mil (0.10mm), minimum line width 4mil (0.10mm ), the minimum clearance is 4mil (0.10mm ). Buried holes, as the name suggests, are buried in the middle of the Plate Layer. They are only used for guidance purposes. blind holes, one exposed on the outside and one hidden on the inside, are usually used for guidance purposes only. Laser (laser) drilling, penetration thickness is less than or equal to 4.5mil, but is made out of a circular table hole. So don't try to use the laser drilling (laser) process to get through the pad. Via can barely be used. So when you place the pad, do not forget the 25mm limit.

Ii. outer line design rules:

(1) ring: the diameter of the PTH (copper hole) hole must be 8 mil larger than that of the single side of the borehole, that is, 16mil larger than that of the borehole. The weld ring of the via hole must be 8mil larger than that of the single side of the borehole and 16mil larger than that of the borehole. In short, whether it is through-hole pad or via, the internal diameter must be greater than 12mil, and the outer diameter must be greater than 28mil, which is very important!

(2) The line width and line distance must be greater than or equal to 4 mil, and the distance between the hole and the hole should not be less than 8 mil. I usually use 10 mil wire width and safe distance, and use 12 mil for copper laying. If any manufacturer has broken down the boards of this condition, change the manufacturer!

(3) the width of the etching word on the outer layer is greater than or equal to 10 mil. Note that it is etching, not silk screen printing!

(4) The line layer is designed with a grid Board (copper-coated grid-like). The rectangle at the blank part of the grid is greater than or equal to 10 * 10mil, the line spacing is not smaller than 10mil when copper is set, and the grid width is greater than or equal to 8mil. When laying a large area of copper, it is recommended to set the materials to a mesh, to prevent the PCB Board substrate and the copper foil adhesive in the immersion welding or heating, the production of Volatile gases and heat is difficult to eliminate, resulting in the expansion and shedding of copper foil. What's more important is the heating performance of grid-like paving. The high-frequency conductivity is much better than the solid laying of the whole block. However, I believe that the advantages of copper mesh cannot be generalized in terms of heat dissipation. In the case that local heating may cause PCB deformation, grid copper should be used to protect the integrity of the PCB based on the thermal dissipation effect. The advantage of copper laying is that, although the Panel temperature has been improved, but it is still within the scope of commercial or industrial standards, and the damage to components is limited. However, if the direct consequence of PCB bending is the appearance of virtual solder points, it may directly cause a line failure. The result of the comparison is that the advantage is small damage. The actual heat dissipation effect should still be best with copper. In practical application, the copper base is laid on the intermediate layer with few grid-like structures, that is, the uneven stress caused by temperature is not as obvious as the surface layer, and the solid copper with better heat dissipation is basically used. This is my statement, which is to be fulfilled in practice!

(5) the distance between the npth hole and copper is greater than or equal to 20mil.

(6) the distance between the copper and the forming line is greater than or equal to 16 mil. Therefore, the distance between the line and the border is not less than 16 mil during layout. In the same way, the distance from copper must be equal to or greater than 16 mil.

(7) the distance between the copper and the forming line is greater than or equal to 20 mil. if you draw a board, it may be produced on a large scale. In order to save costs, it may be required to open the mold, therefore, we must anticipate the design.

(8) V-CUT (generally in the bottom mask and top mask layer draw a line, it is best to mark this place to V-CUT) forming board, according to the thickness of the design;

[1] The thickness is 1.6mm, and the distance between copper and V-CUT is greater than or equal to 0.8mm (32mil ).

[2] The thickness is 1.2mm, and the distance between copper and the V-CUT line is greater than or equal to 0.7mm (28mil ).

[3] The thickness is 0.8-1.0mm, and the distance between copper and V-CUT wire is greater than or equal to 0.6mm (24mil ).

[4] The thickness is less than 8mm, and the distance between copper and V-CUT is greater than or equal to 0.5mm (MIL ).

[5] The distance between the copper and the V-CUT wire is greater than or equal to 1.2mm (MIL ).

Note: Do not set such a small spacing when splicing a board. Try to make it bigger.

3. Design Rules for the inner line:

(1) ring: the diameter of the PTH hole must be larger than that of the single side of the borehole, that is, 16mil. The weld ring of the via hole must be 8mil larger than that of the single side of the borehole and 16mil larger than that of the borehole.
(2) The line width and line distance must be greater than or equal to 4 mil.

(3) the width of the inner etching line is greater than or equal to 10 mil.

(4) the distance between the npth hole and copper is greater than or equal to 20mil.

(5) the distance between the copper and the forming line is greater than or equal to 30mil (generally 40mil ).

(6) the depth of the inner layer without welding rings is drilled to the copper foil at least 10mil (four layers), and the six layers are at least 11mil.

(7) When the line width is less than or equal to 6 mil and there is a drill in the pad, tear drops must be added between the wire and the pad.

(8) The isolation area between two large copper surfaces is above 12mil.

(9) Heat Dissipation pad (plum pad). The distance from the borehole edge to the inner circle is greater than or equal to 8 mil (ring), the distance from the inner circle to the outer circle is greater than or equal to 8 mil, and the opening width is greater than or equal to 8 mil. Generally, there are four openings. At least two or more openings must be guaranteed.

Iv. Welding protection design principles

(1) welding protection is 3mil (clearance) larger than welding pad ). Many software are set by default. You can find them by yourself!

(2) The solder protection distance line (copper) is greater than or equal to 3mil.

(3) the green oil bridge is equal to or greater than 4 mil, that is, the gap between the anti-welding of the IC foot (DAM ).

(4) BGA bits are designed to open windows and overlay cables equal to or greater than 2mil. If this distance is not enough, a skylight is created.

(5) The Golden finger part of the Gold finger board must be open without welding and contain fake fingers.

(8) text wire diameter ≥ 8mi, word height ≥ 32mil.

V. Principles of text design:

(1) The text line width is more than 6 mil, the text line width is higher than 32 Mil, and the text line width is more than 6 mil.

Vi. Design Principles of pore copper and Surface copper

(1) General finished copper 1 oz (35um) Board, Hole Copper 0.7mil (18um ).

(2) General finished copper 2 oz (70um) Board, Hole Copper 0.7mil (18um)-1.4mil (35um ).

7. The above are general design principles. Of course, if you have special requirements, you need to customize the processing technology.

 

The final purpose of PCB layout is to produce applications. When it becomes a formal and valid product, layout's work is regarded as a paragraph. In layout, which common key points should be paid attention to so that the files drawn by myself can effectively comply with the general PCB processing factory rules, so as not to cause unnecessary additional expenses to enterprises?

Based on my years of practical experience and continuous improvement in PCB production technology, I have concluded that the current PCB layout generally follows seven rules:

I. Drilling Design Rules

(1) PCB Board works in principle to design an 8-shaped hole into a groove hole (annular hole ). Therefore, we recommend that you create a ring as much as possible during layout. If you do not have this function, you can place n circles and fold as many as possible. In this way, the Ring Groove won't show "dogs need teeth", and the board manufacturer won't break the drill bit because of your slot hole!

(2) The minimum pore size for mechanical drilling is 0.25mm (10mil). Generally, the aperture design is greater than or equal to 0.3mm (12mil ). If it is smaller than this, it is just 0. 25mm, the people in the board factory will definitely look for you. Why? Find the answer in (5!

(3) The minimum slot hole diameter is 0.25mm (10mil). Generally, the aperture design is greater than or equal to 0.3mm (12mil ). Same as (2 ).

(4) In general practice, only the unit of mechanical drilling is mm, and the remaining unit is mil. The habit of drawing is that in addition to the library, we need to use mm for the volume and size, while the rest use mil for the Unit. The Unit of mil is small, which is really convenient.

(5) generally, the aperture of the laser drilling (laser) is 4mil (0.1mm)-8mil (0.2mm ). Generally, more than 6 layers, and very intensive board, will use this technology, such as mobile phone motherboard, of course, the price will certainly increase by N levels. More importantly, the minimum PCB processing elements: one to three blind buried holes, minimum Laser (laser) drilling 4mil (0.10mm), minimum line width 4mil (0.10mm ), the minimum clearance is 4mil (0.10mm ). Buried holes, as the name suggests, are buried in the middle of the Plate Layer. They are only used for guidance purposes. blind holes, one exposed on the outside and one hidden on the inside, are usually used for guidance purposes only. Laser (laser) drilling, penetration thickness is less than or equal to 4.5mil, but is made out of a circular table hole. So don't try to use the laser drilling (laser) process to get through the pad. Via can barely be used. So when you place the pad, do not forget the 25mm limit.

Ii. outer line design rules:

(1) ring: the diameter of the PTH (copper hole) hole must be 8 mil larger than that of the single side of the borehole, that is, 16mil larger than that of the borehole. The weld ring of the via hole must be 8mil larger than that of the single side of the borehole and 16mil larger than that of the borehole. In short, whether it is through-hole pad or via, the internal diameter must be greater than 12mil, and the outer diameter must be greater than 28mil, which is very important!

(2) The line width and line distance must be greater than or equal to 4 mil, and the distance between the hole and the hole should not be less than 8 mil. I usually use 10 mil wire width and safe distance, and use 12 mil for copper laying. If any manufacturer has broken down the boards of this condition, change the manufacturer!

(3) the width of the etching word on the outer layer is greater than or equal to 10 mil. Note that it is etching, not silk screen printing!

(4) The line layer is designed with a grid Board (copper-coated grid-like). The rectangle at the blank part of the grid is greater than or equal to 10 * 10mil, the line spacing is not smaller than 10mil when copper is set, and the grid width is greater than or equal to 8mil. When laying a large area of copper, it is recommended to set the materials to a mesh, to prevent the PCB Board substrate and the copper foil adhesive in the immersion welding or heating, the production of Volatile gases and heat is difficult to eliminate, resulting in the expansion and shedding of copper foil. What's more important is the heating performance of grid-like paving. The high-frequency conductivity is much better than the solid laying of the whole block. However, I believe that the advantages of copper mesh cannot be generalized in terms of heat dissipation. In the case that local heating may cause PCB deformation, grid copper should be used to protect the integrity of the PCB based on the thermal dissipation effect. The advantage of copper laying is that, although the Panel temperature has been improved, but it is still within the scope of commercial or industrial standards, and the damage to components is limited. However, if the direct consequence of PCB bending is the appearance of virtual solder points, it may directly cause a line failure. The result of the comparison is that the advantage is small damage. The actual heat dissipation effect should still be best with copper. In practical application, the copper base is laid on the intermediate layer with few grid-like structures, that is, the uneven stress caused by temperature is not as obvious as the surface layer, and the solid copper with better heat dissipation is basically used. This is my statement, which is to be fulfilled in practice!

(5) the distance between the npth hole and copper is greater than or equal to 20mil.

(6) the distance between the copper and the forming line is greater than or equal to 16 mil. Therefore, the distance between the line and the border is not less than 16 mil during layout. In the same way, the distance from copper must be equal to or greater than 16 mil.

(7) the distance between the copper and the forming line is greater than or equal to 20 mil. if you draw a board, it may be produced on a large scale. In order to save costs, it may be required to open the mold, therefore, we must anticipate the design.

(8) V-CUT (generally in the bottom mask and top mask layer draw a line, it is best to mark this place to V-CUT) forming board, according to the thickness of the design;

[1] The thickness is 1.6mm, and the distance between copper and V-CUT is greater than or equal to 0.8mm (32mil ).

[2] The thickness is 1.2mm, and the distance between copper and the V-CUT line is greater than or equal to 0.7mm (28mil ).

[3] The thickness is 0.8-1.0mm, and the distance between copper and V-CUT wire is greater than or equal to 0.6mm (24mil ).

[4] The thickness is less than 8mm, and the distance between copper and V-CUT is greater than or equal to 0.5mm (MIL ).

[5] The distance between the copper and the V-CUT wire is greater than or equal to 1.2mm (MIL ).

Note: Do not set such a small spacing when splicing a board. Try to make it bigger.

3. Design Rules for the inner line:

(1) ring: the diameter of the PTH hole must be larger than that of the single side of the borehole, that is, 16mil. The weld ring of the via hole must be 8mil larger than that of the single side of the borehole and 16mil larger than that of the borehole.
(2) The line width and line distance must be greater than or equal to 4 mil.

(3) the width of the inner etching line is greater than or equal to 10 mil.

(4) the distance between the npth hole and copper is greater than or equal to 20mil.

(5) the distance between the copper and the forming line is greater than or equal to 30mil (generally 40mil ).

(6) the depth of the inner layer without welding rings is drilled to the copper foil at least 10mil (four layers), and the six layers are at least 11mil.

(7) When the line width is less than or equal to 6 mil and there is a drill in the pad, tear drops must be added between the wire and the pad.

(8) The isolation area between two large copper surfaces is above 12mil.

(9) Heat Dissipation pad (plum pad). The distance from the borehole edge to the inner circle is greater than or equal to 8 mil (ring), the distance from the inner circle to the outer circle is greater than or equal to 8 mil, and the opening width is greater than or equal to 8 mil. Generally, there are four openings. At least two or more openings must be guaranteed.

Iv. Welding protection design principles

(1) welding protection is 3mil (clearance) larger than welding pad ). Many software are set by default. You can find them by yourself!

(2) The solder protection distance line (copper) is greater than or equal to 3mil.

(3) the green oil bridge is equal to or greater than 4 mil, that is, the gap between the anti-welding of the IC foot (DAM ).

(4) BGA bits are designed to open windows and overlay cables equal to or greater than 2mil. If this distance is not enough, a skylight is created.

(5) The Golden finger part of the Gold finger board must be open without welding and contain fake fingers.

(8) text wire diameter ≥ 8mi, word height ≥ 32mil.

V. Principles of text design:

(1) The text line width is more than 6 mil, the text line width is higher than 32 Mil, and the text line width is more than 6 mil.

Vi. Design Principles of pore copper and Surface copper

(1) General finished copper 1 oz (35um) Board, Hole Copper 0.7mil (18um ).

(2) General finished copper 2 oz (70um) Board, Hole Copper 0.7mil (18um)-1.4mil (35um ).

7. The above are general design principles. Of course, if you have special requirements, you need to customize the processing technology.