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PADS Power V3 (.ASC) Write

Overview

CAMCAD creates a PADS Power ASCII .ASC file. This is an ASCII file that is very easy to read into PADS Power V 3.X.

For directions on loading this file into PADS Power PCB, please see the Using the PADS File section.

Versions Supported

Reaction of files loaded into version 3.x will be the deciding factor on any reported errors regarding file loading and compatibility with Pads Power.

Specific Export Procedures

In CAMCAD go to File | Export. Select PADS Power V3 Layout Write. The Save As window appears. Give the file a name (CAMCAD will by default append the .ASC extension if you do not) and click Save.

The PADS Export Format window will appear. Use this window to customize the format of the PADS file, including units and component/flash information. Click OK.

After that you will have to map your layers. The PADS Layer Editor window will appear. Most necessary layers will already be mapped to the appropriate layers in Pads. This is true for known electrical, pad, soldermask, pastemask, silkscreen, and board outline layers (layers that are correctly typed in the CAMCAD environment). The automatically mapped layers should not be modified unless there is expressed need to do so. Any layer without a default mapping may be turned on for translation and mapped to a specific layer number in the Pads system. 

In column 1 (Stack) the Electrical stackup of the layer is defined. Typically only Etch and Pad layers will have an electrical stack number (1..n) or electrical surface (TOP, BOTTOM, INNER, ALL) defined. In the case of the Pads output the automatically mapped layers will receive a stack equal to the target Pads layer number. These should not be changed except to set them to "No Physical" if you are overriding the default mapping. The Stack of "No Physical" essentially assigns the layer as a non-electrical, or documentation, layer.

Column 2 (On) displays the translation status of the layer. An X in this column shows that the layer will be translated. A blank " " in this column shows that the layer will not be translated.

Column 3 (Type) shows the CAMCAD identified layer type. There are three layer types that are possible in this column. Type D identifies a layer as Documentation. Type S identifies a layer as Signal/Electrical. Type P identifies a layer as Plane/Negative. The identified layer types should not be modified unless there is an expressed need to do so.

In column 4 (CAMCAD Name) is the layer name as it is presented in the CAMCAD environment. This is typically the same as the layer name from the source ECAD package. This column of information can not be modified through the layer edit dialogue and is basically the unique index field for this table.

In column 5 (Pads Layer Name) the PADS target layer number. 

  • Some of the default mapped layers are mapped to theoretical layers in Pads. 
    • These are pad shape layers for top, bottom, inner, and all pad layers in the Pads system. The layers -4, -2, and -1 (pad all, pad bottom, and pad top respectively) are not selectable in the layer edit dialogue, therefore, any layer with a default mapping to these special layer numbers should not be changed. 
    • There is one more special Pads target  layer number. Pads Layer Number 0 is the layer in Pads that contains the board outline. Only the layer containing the board outline should be mapped to layer 0. 
  • The electrical layers in Pads are from 1 (TOP) to the bottom electrical with a maximum of 20 (layers 1..20) electrical layers. CAMCAD calculates the number of electrical layers prior to displaying the layer mapping dialogue, therefore, the electrical stackup and number of electrical layers can not be changed during the layer mapping. This means that if you are translating a board with 6 electrical layers the default mapping will map the top electrical layer to Pads Layer Number 1, the bottom electrical layer to Pads Layer Number 6, and the inner electrical layers in order of their electrical stackup to Pads Layer numbers 2 through 5. If it is desired to make this an 8 layer board in Pads one might be compelled to change the Stack and Pads Layer Number of the bottom electrical layer to 8, however, this is incorrect as CAMCAD knows this as a 6 electrical layer board and the result will be that the bottom electrical information will be written to the Pads Layer Number 8 which will be a documentation (non-electrical) layer in the Pads System and Pads will understand this as a 6 layer board from Top (layer 1) to Bottom (layer 6).
  • The documentation layers may be mapped to any non-electrical Pads Layer Number. If the design being translated has 8 electrical layers then Pads Layer Numbers 1 through 8 will be used for electrical layer data. Any of the other layers, 9 through 30, can be used as the target Pads layer for any documentation layer.

You may want to turn some layers off/on- this will all depend on which layers you want to use.

The configuration file we use is a file called PADS.out. This file can be changed (edited) to reflect the desired layers you may want to use. Keep in mind your PADS.out will have to agree with the layers you assign in the layer mapping.

Tips, Notes and Exporting Questions

What changes need to be made to a plane area for that area to be written to Pads as a POUROUT (pour outline) with no HATOUT (hatch outline)?

In order to properly write a POUROUT to pads without a HATOUT you will need to change the following

  1. The PolyStructure being translated to Pads must have "1" and ONLY "1" poly defined. If the polystructure you are working with has more then one poly defined, you will need to use menu command EDIT | POLYS | UNLINK SELECTED POLYS (With poly selected). This will seperate the poly structure so that each poly in the structure is it's own poly. Polys being written to Pads as a POUROUT only MUST ONLY HAVE ONE POLY defined.
  2. Furthermore, the poly must NOT BE FLAGGED AS FILLED. If the poly is filled, CAMCAD will write the HATOUT. When the poly is QUERIED in CAMCAD, the QUERY dialog has an "EDIT POLY ITEM" button.... this is where the properties of the poly can be changed. Also, the poly will need to be flagged as "CLOSED" and also flagged as "BOUNDARY".

If each of these requirements are met in the defintion of the poly.... the result will be a written POUROUT to the Pads file and NOT a HATOUT. This makes for re-pouring those boundaries in Pads much less painful.

Filled/Poured planes - To translate or not to translate... 

Pads does not work well with complex poured planes that were not generated in the Pads system. 

Some ECAD systems, such as OrCAD, store only the pour outline. These types of pours translate well into Pads and can be setup (clearance and other pour parameters) and re-poured in Pads. 

Other ECAD systems may store the "generated" pour outline and associative void areas. Although this is similar to how Pads stores the generated pour data in the ASC file, the binary database stores the pour outline and the pour must be re-generated after the design is loaded. These types of pours may result in display list errors on import into Pads and will render in the pour unusable (it will likely need to be deleted in Pads and be re-digitized). 

There are two other types of pours that will cause many problems in the Pads system. These pour types are 

1. The hatch fill - ECAD system stores a generated outline, outlines around cleared areas, and the actual hatch lines. This can result in thousands of individual line segments (This is common with Protel).

2. Line Crack/Breakout Clearances - ECAD system incorporates the voided or cleared areas into the primary pour outline. This can result in a single polygon thousands of endpoints (vertices) and will likely contain overlapping or coincident lines (This is common with Mentor).

It is suggested not to translate these types of pours to Pads at all and re-enter the pours in the Pads design environment. Though this sounds easy enough there is no quick and easy way to turn off the writing of pours to Pads, instead, it is a manual process of either removing the pours in the source ECAD system and regenerating the data to load into CAMCAD or by deleting the poured regions in the CAMCAD environment.

Why aren't filled areas displayed in PADS?

This is usually due to filled areas that are overlapped. PADS does not accept overlapping fills.

Why are some of the bottom SMD pads the wrong shape or size?

In some systems Surface Mount pads can have a different size pads on the bottom when mounted on that surface. Pads can only have one size and we translate the Top pad in all cases.

Why didn't the "Oblong"shape pads/drill come through?

Some systems (like Orcad) can create and oblong pad/drilled hole. PADS does not accept these shapes and only gives you a round pad and drill.

Why are some pins not showing as connected in PADS, and still showing the RatsNest?

In Pads the vertacies of a Pad insertation point and the trace/copper line end point must match exactly for Pads to recognize the connection and rid the trace of the RatsNest. Some other systems (Like PCAD) recognize connections based on the electrical layer and the copper areas touching. This is not acceptable in PADS.

Why Didn't the Cross fills come into Pads?

Cross Fills/hatching is not allowed in Pads Power.

Why are some of the copper fills different?

The width outline of copper fills very from system to system, the radius of the line draw in Orcad is in the center of the line. In Pads Power the radius is taken from the outside of the edge of the radius.

Why does some text not come through?

In some cases text will not come through because it was drawn with Linear text.

How to connect thermal ties in Pads.

Start off by changing the layer status. The layer you want to add ties to must be changed to a CAM layer. Assign the proper nets to it. Next set the "Selection Filter" to Pins (only). Now choose Select All. Click the right mouse button and choose Query/Modify. I n the box you now can click on Plane Thermal. Click on apply. You need to repeat the same steps for "Vias" only.

Why must Fill areas be redefined?

Once you are in Pads Power you will have to redefine your power planes before you try and refill them. If you do not do this strange fill areas may show up where you do not want them.

Part Decal Limits.

The maximum pads per component is 2048.

Blind VIA translation -

When translating from any ECAD format to PADS and specifically when translating BLIND VIA's... it is best to remove the attribute keyword "BLIND" from the geometry level (Done in CAMCAD Navigator) and also from all inserts of the VIA geometry (Done in Automated Attribute Assignment). This will prevent CAMCAD from writing the VIA in a "non blind" way. When CAMCAD does this "non blind" conversion it basically will add pads to all layers of which the via should span if it was not blind. This will give incorrect results, but the PADS system will accept the ASCII file without issue.

Information on Placement Dependent Geometries - Mentor Boardstation Layout Translations to Other ECAD Systems

During a Router Solutions translation from a Placement Dependant CAD System to a Non Placement Dependant CAD System, there are certain design practices that are legal in Placement Dependant CAD Systems which are not compatible with Non Placement Dependant CAD System. In Placement Dependant CAD Systems, geometries can be created to have different pin layouts depending on which surface of the board the geometry is inserted. CAMCAD will translate the geometry as is (including all pins), not considering which surface the referencing component is placed. It will be the responsibility of the customer to repair/rework these geometries in the target CAD system. Router Solutions can offer suggestions to customers for uncovering problematic components. However, Router Solutions is not responsible for providing a toolset for customers to use for this error correction, or for providing the error correction itself. An example of a Placement Dependant CAD System is Mentor. An example of a Non Placement Dependant CAD System is PADS.

Information on Padshape offsets when writing PADS data from CAMCAD

When Writing Data to the PADS *.ASC format, Padshapes can only have certain types of origin offsets to be "Acceptable" for the PADS System. Here is a diagram of this acceptable region of padshape offseting: