The Dialog for STEP 3D Export

Abstract

STEP = STandard for the Exchange of Product model data

Find the dialog for the STEP Export in menu:
File|Input/Output Formats|File transfer/documentation|Step export(3D)...

Image 1: The Step Export Dialog as it opens. It consists of the main sections Quick selection and Details.

The section Quick selection

Check the complete PCB with an external CAD for the housing
Use this option if you want to give over the complete assembly (PCB including all devices assembled). Only the inner details of the PCB body which can't be seen from outside are omitted. The ground plane is idle here but can be added later.
Check the pure PCB only with an external CAD for the housing
Use this option if you want to give over only the PCB body. This means only the part which is manufactured in FR4 material.
Simulate the electrical functions of the PCB with external tools
Use this option in order to give over the PCB body with all inner and outer technical details (tracks, pads, vias, drill holes...) without components.

The section Details

Select from the following tabs:

AP = Application Protocol

An AP covers a particular application and industry domain:

• AP 203 Configuration Controlled Design
• AP 210 Electronic Printed Circuit Assembly, Design and Manufacturing
• AP 214 Core Data for Automotive Mechanical Design Processes

Only some APs are implemented in your 3D program. AP 203 is a basic AP which at least will be supported by your system. You will notice only one difference in the data:

• STEP AP 203: single-colored
• STEP AP 210: four-colored

Selection

In tab Selection determines which elements are going to be overgiven to the STEP format. No changes have taken place here since the last version.

Detail truth

Detail truth means model fidelity - the model's level of matching with reality.

Components in color or monochrome.

Output PCB outline with exact coordinates:
The normal algorithm to calculate the PCB outline shows an inaccuracy of some µm. The outline of the PCB optionally can be calculated by a more accurate algorithm.

The outline of the PCB is calculated by an algorithm which shows an impreciseness of a few µm. You can select a precise algorithm which avoids this.

Output ground plane:

A ground plane can be converted to STEP though in the TARGET 3D viewer upt to now (may 2014) it can not be displayed. Activate this box if indicated.

Output details for simulators (conducting via hull and solder with THT):

Abundance of details goes along between the poles of necessity and file size. To simulate the electrical behaviour of the 3D PCB sufficiently details are needed. Tick the box here so that the STEP exportembraces it accordingly. Ground planes and assemblies are ticked automatically. The quick selection also ticks the required boxes automatically. "Components" are unticked because they aren't needed for simulation.

The layout of the printed circuit board, the placement of the components and the structure of the power layer can have its own effect on the electrical performance of the circuit. There may be problems with EMC, power integrity and signal integrity. Below you will find helpful links on the subject. By this means you can analyse your board on such effects for example using the simulation tool CST.

https://www.cst.com/Products/CSTPCBS
https://www.cst.com/Applications/Category/Signal+Integrity+and+Power+Integrity
https://www.cst.com/Applications/Article/Signal-Integrity-Analysis-Of-A-Complex-Multi-Layered-Package
http://en.wikipedia.org/wiki/Signal_integrity
http://en.wikipedia.org/wiki/Computational_electromagnetics

Sizes (= parameters)

Extras

Also see chapter 5 at option "Locking all parts of an imported STEP assembly e.g. in Solidworks".

Using the option "Generate assemblies..." the STEP-Import in your CAD might show a hint e.g. in Rhinoceros

In your CAD there will be a function "Explode", which is able to divide objects in a hierarchy (cascading).

PIC exploded:

Important element groups can be divided into various sub entities. A first explosion separates the following objects:

• PCB body
• electroconductive objects (Tracks, Pads, Vias, Ground planes...)
• component 1
• component 2
• component ...

In this first stage of explosion within your 3D CAD system it is possible to assign material properties (e.g. "copper") to the electroconductive objects of your projects. Now let the electroconductive parts explode again so that single signals for instance can be touched/inspected/treated separately (galvanic separation).

Approximations

Some 3D programs offer only a rudimentary STEP import. Some STEP surfaces e.g. CYLINDRICAL_SURFACE are not implemented or inaccurate. These surfaces can be approximated by a polyhedron; i.e. made up of only PLANEs.

File load time

It takes some minutes to load a STEP file! This load time increases if some polyeder approximations are applied. A 3D viewer does the import much faster than a 3D-CAD program! Currently implemented STEP elements: CARTESIAN_POINT, VERTEX_POINT, LINE, CIRCLE, PLANE, CYLINDRICAL_SURFACE, TOROIDAL_SURFACE, SPHERICAL_SURFACE, DIRECTION, VECTOR, AXIS2_PLACEMENT_3D, ADVANCED_FACE, FACE_BOUND, FACE_OUTER_BOUND, ORIENTED_EDGE, EDGE_CURVE, EDGE_LOOP, CLOSED_SHELL, MANIFOLD_SOLID_BREP, STYLED_ITEM, MECHANICAL_DESIGN_GEOMETRIC_PRESENTATION_REPRESENTATION

Switch off all options to reduce load time in Solid Edge:

Locking all parts of an imported STEP assembly e.g. in Solidworks

Wenn Sie im Reiter "Extras" die Option "Ausgabe für Solidworks optimieren" wählen und gleichzeitig die Option "Baugruppen erzeugen" nicht wählen, werden keine Unterbaugruppen erzeugt. Sie erhalten damit fixierte Elemente. Sobald Sie jedoch Unterbaugruppen erzeugen, kommt es zu folgendem Problem:

In STEP gibt es leider keine Möglichkeit der Fixierung von Unterbaugruppen. Wenn Sie etwa das Solidworks-Beispiel "box_with_lid" in Solidworks als STEP exportieren und wieder importieren, fehlen die Fixierungen.

In Solidworks fehlen Fixierungen

Bild: Fixierungen sind in STEP nicht vorgesehen.

Link zu diesem Thread ins Solidworks-Forum:

https://forum.solidworks.com/thread/49885

TARGET-Projekt pic.T3001 in Solidworks

Bild: Wenn man das TARGET - Projekt pic.T3001 nach STEP exportiert und in Solidworks importiert, sind die Unterbaugruppen nicht fixiert.

Unterbaugruppen fixieren

Bild: Alle Unterbaugruppen markieren und mit der rechten Maustaste den Unterpunkt "Fixieren" wählen.

Unterbaugruppen fixiert

Bild: Die Unterbaugruppen sind nun fixiert und mit einem vorgestellten (f) ausgezeichnet.

Im Datei-Öffnen-Dialog von Solidworks können Sie STEP auswählen. In diesem Dialog gibt es auch eine Schaltfläche "Optionen". Hier können Sie noch den STEP-Import nach Ihren Wünschen beeinflussen.