Shulou(Shulou.com)06/01 Report--

In this issue, the editor will bring you what to do about the problems encountered by beginners using PADS. The article is rich in content and analyzes and narrates it from a professional point of view. I hope you can get something after reading this article.

Beginners to PADS also have to start with new components and packages.

Open PADS Logic- > File-> New. To start by creating a new component, click the component editor under the tool

Edit-> CAE package Editor in the menu bar of the component editing interface

Or edit graphics on the toolbar

Pop-up editing door package editing dialog box

Here are a few questions for beginners:

1. Why does a component have doors A, B, etc.

Just like the sub-master in protel, for example, a multi-channel and door chip, which assumes that there are two and gates, can be named door An and door B. on the schematic diagram, door An and door B can be represented as two separate components that are actually one component.

2. What do you mean by alternative packaging

The alternative package is the CAE package in PADS. For example, the capacitor has a laminated chip capacitor and an electrolytic capacitor. As shown in the following figure, the left is a laminated chip capacitor and the right is an electrolytic capacitor. When the two packages are drawn in a component, you can choose the CAE package according to the situation.

Even if the new component is known to the novice, you can start with it. After the component is newly created, you need to assign the package to the component. Also, edit-> component type editor on the component editing interface menu bar, or edit the electrical parameters on the toolbar. Select PCB package in the pop-up dialog box. Select all packages corresponding to the component in the unassigned package and assign them to the right. In this way, you can adjust the desired package at any time in the schematic and layout, and create a new package if you don't have the desired package.

If the package is newly built in layout, it should be noted that in principle, the package should be larger than the package given in the specification, which takes into account the need to climb tin during welding, otherwise there may be a lot of false welding.

Here are some problems or questions that beginners will encounter:

1. What should I do if the imported dxf file cannot be converted to a board frame?

Many times the structure of the dxf file is not a closed graphics, so it is impossible to turn dxf into a board frame, in CAD, you need to merge the segments that make up a closed graph into a whole, sometimes it looks like two segments are connected at the end of the head, but in fact, after magnifying the two lines separate, you must first ensure that the frame is a whole, there can be no extension of a certain line segment, all line segments need to be connected into a whole.

two。 What is a flying line?

After the schematic diagram is drawn and sent to the layout Netlist, there will be many white lines connecting the different pins of each component. These lines are flying wires, and the pins connected by the flying wire indicate an electrical connection. These wires only indicate that there is electrical connectivity. It is not really connected until the wires have been laid.

3. How do you cover it with copper?

Copper cladding is a large area of copper cloth, which is used in basic local networks. Encircle the area to be covered with copper.

The white circle outside is the area to be clad with copper. You can choose the layer and network where the clad copper is located.

4. What is the difference between copper cladding and copper foil?

Copper cladding is a large area of cloth copper, copper foil is painted where there will be copper

5. What if there is a grid after copper cladding?

As shown in the following figure

That's because the width of the clad is smaller than the size of the copper foil, so it can be adjusted slightly.

6. How do you expose the copper?

Copper exposure is to expose copper at a specified position on the PCB board, without green oil cover, just draw a piece of copper foil in the Solder Mask layer (solder resistance layer).

7. What is the Soldermask layer (solder resistance layer) and what is the paste mask layer (solder flux layer)?

Solder resistance layer, also known as window layer, green oil layer, is the place where green oil is spread on the PCB, why it is called solder resistance layer, because the place with green oil can not be welded, and the solder resistance layer is output in the form of negative film, so draw a shape mapping on the solder resistance layer on the board, not on the green oil but expose the copper skin, that is, open the window.

The welding flux layer is the steel mesh layer, which can let the solder paste flow into the exact position when the tin is applied.

8. What documents do you need to make the board?

PCB board factory needs what documents to make the board, directly provide pcb source files of course, but for commercial confidentiality will not do so, provide Gerber documents to the board factory on it.

What does it mean to cover with white oil under 9.BGA?

Sometimes in order to make room for the wiring, some useless pads packaged by BGA may not be drawn or moved to other pads, at this time, if there is a wire or through hole directly below the pin, it is very likely that the green oil cover is not in place will cause a short circuit, so draw a piece of copper foil on the screen printing layer to further cover the surface, not only under the GBA package. All those with wires or holes under the chip and pins and pads on the chip floor should be covered with white oil.

The above is what the novice editor shared with PADS should do. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

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