Проектирование гибко-жестких плат в Altium Designer | Altium

3d movie maker support for rigid-flex designs

The ability to fold a rigid-flex design can also be captured as a 3D movie. It is very simple to do and does not require the use of movie key frames during the folding sequence.

Refer to the PCB 3D Video page for a detailed description of how to make a 3D movie. As a basic guide:

Adding and configuring a coverlay

Coverlay layers are added in the Layer Stack Manager. To add coverlay layers:

1. Enable the Is Flex option for the flex substack.
2. Right-click on the appropriate layer(s) and select the Insert layer above (below) » Coverlay command to add coverlays.
3. Define the properties of the coverlay, including the Coverlay expansion property. If the Coverlay expansion column is not visible, right-click on an existing column heading to open the Select Columns dialog, where it can be enabled.
4. Save the layer stack to reflect the changes on the board.
5. In Board Planning mode there will now be additional tabs for each coverlay layer added in the stack. Note that the color of the coverlay is defined by the layer color (View Configuration panel), not the color assigned in the Layer Stack Manager.

Add the coverlay layer(s) into the substack and configure the layer properties in the Layer Stack Manager.

Additional drawing detail

1. A drill table detailing finished hole size, associated tolerances and plated/not plated.
2. A dimensional drawing, including reference datum(s), critical dimensions, rigid to flex interfaces, bend location and direction markers.
3. Panelization detail, if required.
4. Construction and Layer detail, detailing material used for each layer, thicknesses and copper weights.

Coverlay polygon

Coverlay Polygons can be placed when a PCB editor is in Board Planning Mode. Select the Design » Place Coverlay Polygon command from the main menus.

Coverlay polygon placement modes

• While placing a polygon there are five available corner modes, four of which also have corner direction sub-modes. During placement:
• Press Shift Spacebar to cycle through the five available corner modes.
• Press Spacebar to toggle between the two corner direction sub-modes.
• When in either of the arc corner modes, hold the arrow keys to shrink or grow the arc. Hold the Shift key as you press to accelerate arc resizing.
• Press the 1 shortcut key to toggle between placing two edges per click or one edge per click. In the second mode, the dashed edge is referred to as the look-ahead segment (as shown in the last image in the set below).
• Press the Backspace key to remove the last vertex.

Press Shift Spacebar to cycle through the five available corner modes, press the 1 shortcut to toggle placement between two edges or one edge.

Defining the board shape and regions

The layer stack defines the board in the vertical direction, or Z plane. In the PCB editor, the area that the board occupies in the X and Y planes is defined by the Board Shape. The board shape can be a polygonal region of any shape, with straight or curved edges that lie at any angle, that can also include cutouts (internal holes) of any shape.

There are two techniques that can be used to defining the overall board shape and the various rigid and flex regions:

1. Define the overall board shape, and then slice it into regions. Learn more about defining the Board Shape.
2. Place each rigid and flex Board Region in the workspace to build up the final board shape. Learn more about placing Board Regions.

The final shape can be created using a mixture of the two techniques.

The overall Board Shape is defined by the set of Board Regions, the video shows two ways these regions can be created.

Defining the Board Shape and Regions:

• The board shape can be defined interactively in Board Planning Mode (View » Board Planning Mode), or it can be defined based on an existing outline in 2D layout mode (View » 2D Layout Mode).
• To define the board shape from an existing outline, select the outline in 2D layout mode and run the Design » Board Shape » Define from selected objects command (or the Tools » Convert » Create Board Region from selected primitives command). The software will trace along the centerline of the selected track/arc objects to define the outer edge of the board shape.
• To define the board shape interactively, switch to Board Planning Mode and select the Place » Board Region command (or click the  button on the Active Bar). The standard region object placement behaviors apply, use the Snap Grid and workspace Guides to help with this process. Enable the Board Shape option in the Snap Options palette to give the best level of control during Board Region editing. Learn more about Understanding the Snap Behavior.
• Place the required number of Regions. Regions can be drawn so they are overlapped, note that this does not define the extent that a flex region overlaps into a rigid region, that is defined by the Intrusion values in the Stackup definition.
• To define the Name and assign a Layer stack for each region, select the region and edit the properties in the Board Region mode of the Properties panel.
• To slice a Board Region into two smaller regions, use the Design » Slice Board Region command (or click the  button on the Active Bar). The Slicing tool uses the standard line placement cornering modes, including 45°, 90°, 45° arc, 90° arc and any angle, press Shift Spacebar to change the mode during slicing.
• The location and shape of an existing Board Region can be edited, using the standard polygonal object editing techniques.

► Learn more about Rigid & Flex Regions Planning in Advanced Rigid-Flex Mode

Designing a flex-only pcb (advanced mode)

A flex-only board can only be created in Advanced Rigid-Flex mode.

The Layer Stack Manager requires at least one rigid substack to be defined. To design a flex-only PCB, first define the rigid substack then add a flex substack, as shown in the image below.

A flex-only board still requires a rigid substack to be defined in the Layer Stack Manager.

In Board Planning Mode, define the shape of the flex-only PCB and assign the flex substack in the Board Region mode of the Properties panel.

A flex-only PCB, hover the cursor over the image to show the board in 3D.

Designing a rigid-flex pcb

A printed circuit board is designed as a series of layers stacked on top of one another. For a traditional rigid printed circuit board, the board shape defines the board in the X-Y plane, and the stack of layers defines the board in the Z plane. The X-Y board shape is defined in the main PCB editing window, and the layers are configured in the Layer Stack Manager.

To design a rigid-flex board, you need to:

• Enable the required Rigid-Flex mode (Layer Stack Manager, Tools » Features » Rigid-Flex, or Tools » Features » Rigid-Flex (Advanced) command)
• Define the Substack needed for each Region of the board, and configure how those Substacks align with each other in the Z plane.
• Define the shape of each rigid and flex Region in the X-Y plane, and assign the correct Substack to each Region.

Documentation and drawing requirements

Typical suggested documentation requirements, include: 

Editing or placing additional coverlay

Coverlay is automatically added to cover the entire area of the Board Region it was added to, as shown in the image below (in accordance with the Coverlay expansion value defined in the Layer Stack Manager). Behaving like an additional solder mask layer, openings are automatically created for component pads in accordance with the applicable Solder Mask Expansion design rule, or else the settings defined for the Pad if the Solder Mask Expansions setting has been configured to override the design rule.

Openings in the coverlay for the component pads is controlled by the applicable Solder Mask Expansion design rule (which can be overridden by local pad settings).

To edit the coverlay:

A section of custom coverlay has been placed and a cutout is about to be defined in it.

When the Coverlay layer is the active layer, clicking on the Board Region will select the Coverlay, not the region. To be able to select the Board Region or a Bending Line you must switch to a different layer, for example the Multi-Layer.

Enabling and viewing the coverlay

If coverlay layers are added to the substack before that substack is assigned to a Board Region, the coverlay objects will be present when the substack is assigned to a Board Region.

If coverlay layers are added to the substack after that substack has already been assigned to a Board Region, then coverlays must be added to that region. Coverlays can be added in Board Planning mode by selecting the Board Region and then either:

• In Standard Rigid-Flex mode:
  • Double-click on the flex region to open the Board Region dialog, and enable the Custom Coverlays option.
• In Advanced RIgid-Flex mode:
  • Right-clicking on the region and selecting the Coverlay Actions » Add Coverlay command, or
  • Clicking the Add Coverlay button in the Board Region mode of the Properties panel.

If the Board Region had the substack assigned before the coverlays were added in the LSM, use the right-click command or the panel button to add them to that region.

Note the additional tab for each coverlay layer added in the substack, click on a layer tab to make that layer the current layer, and examine or edit the coverlay.

Enabling rigid-flex design

To support the complex structures present in a modern rigid-flex printed circuit board, the Z plane editor — the Layer Stack Manager, provides different display modes for editing the structure of your board. Select the Design » Layer Stack Manager command to open the Layer Stack Manager, where you can enable the required rigid-flex mode, and create and align the Substacks needed in your rigid-flex design.

When the Layer Stack Manager opens, it will show the current board layer Stackup. For a new PCB, this will be a simple two-layer board. To enable the features needed to design a rigid-flex board, open the Tools » Features sub-menu or click the Features button () to select either the Rigid-Flex command, or the Rigid-Flex (Advanced) command.Select the command to enable the required rigid-flex mode.

Flex and rigid-flex layer stackup types

There are a number of standard stackups available for flex and rigid-flex circuits, referred to as Types. These are summarized below.

Graphical editing of a coverlay polygon

This method of editing allows you to select a placed coverlay polygon object directly in the design space and graphically change its size, shape or location.

Click once on a coverlay polygon object to select it, which puts it into edit mode. The outer shape of the coverlay polygon object is defined by a series of edges, where each edge is represented by an end vertex at each end, shown as a solid white square, and a center vertex in the middle is shown as a hollow white square. Each end vertex represents the location where two edges meet.

A selected Coverlay Polygon

How output is generated for coverlay layers

When the output is generated, each layer is output as separate data. For example, when Gerber is generated, the top solder mask is written to one Gerber file, the top coverlay is written to another Gerber file.

The output for a coverlay can be divided into 2 categories:

The centerline of the 1mil wide closed polyline is the edge of the coverlay.

Examining the Gerber output in a CAM viewer — the blue is the coverlay layer, the purple is the top solder mask layer.

Zoomed in, a custom coverlay cutout is selected — as with the coverlay outline the cutout is also defined as a closed polyline.

Including coverlay on a flex region

A common feature on rigid-flex boards is the selective use of coverlay material. This insulation layer is cut and laminated onto specific areas of the board, and because of this selective use, coverlay is also referred to as bikini coverlay.

An example of a custom coverlay

Layer stack outputs

• ODB
• IPC2581B
• Layer Stack Report

Materials used in flexible circuit manufacture

Flex circuits are created from a stackup of flexible substrate material and copper, laminated together with adhesive, heat and pressure.

The most common substrate is polyimide, a strong, yet flexible thermosetting polymer (thermoset). Examples of polyimides often used in the manufacture of flexible circuits include: Apical, Kapton, UPILEX, VTEC PI, Norton TH and Kaptrex. Note that these are registered trade names, owned by their respective trademark holders.

The copper layer is typically rolled and annealed (RA) copper, or sometimes wrought copper. These forms of copper are produced as a foil and offer excellent flexibility. They have an elongated grain, it is important to orient this correctly in a dynamic flex circuit to achieve the maximum flexing lifespan.

This is achieved by orienting the dynamic flex circuit along the roll (so the circuit bends in the same way the foil was coiled on the roll). The flex manufacturer normally deals with this during the preparation of fabrication panels, it only becomes an issue if the designer performs their own circuit panelization (referred to as nesting in flex circuit design).

The adhesive is typically acrylic, and as the softest material in the structure, introduces the greatest number of manufacturing challenges. These include: squeeze-out, where the adhesive is squeezed out into openings cut into the cover layers to access copper layers;

Z-axis expansion defects due to the higher CTE (coefficient of thermal expansion) of acrylic adhesive; and moisture out gassing due to the higher rate of moisture absorbance, which can result in resin recession, blow outs and delamination at plated through hole sites.

   A simplified view of how a flexible circuit is manufactured, the materials are laminated together under heat and pressure.

Mechanical rigid-flex design

Designing a flex or rigid-flex circuit is very much an electromechanical process. Designing any PCB is a three-dimensional design process, but for a flex or rigid-flex design, the three-dimensional requirements are much more important. Why? Because the rigid-flex board may attach to multiple surfaces within the product enclosure, with the attaching and folding process often happening during product assembly.

Delivering a working electromechanical design requires close and constant collaboration between the mechanical and electrical engineering teams. The traditional approach to confirm that the folded board fits within its enclosure has been to create a mechanical mockup — known as a paper doll cut out. By its very nature, it’s difficult to achieve the accuracy and realism required with this approach.

A board with two rigid regions connected by a flexible region in the ECAD PCB editor and in MCAD.

Altium is helping to solve this challenge with CoDesigner, a sophisticated mechanical-to-electronic design interface technology. CoDesigner allows the engineers to pass the board shape and component changes back and forth between the ECAD and MCAD design domains directly from within the ECAD and MCAD design software.

Prints

• Prints can be configured as required.

References

Flex and Rigid-Flex Circuits Technical Engineering Guide — Epec Engineering Technologies

Flexible Circuit Technology — Joe Fjelstad

Flex Circuits Design Guide — Minco Products Inc

Minco Products Flex Resources

Machine Design website:

Tool outputs

• NC / Excellon Route Tool Path — generated from outline for polyline objects.

Type 2 — double layer

Double-sided flexible printed wiring containing two conductive layers with plated through holes, with or without stiffeners.

Type 3 — multilayer

Multilayer flexible printed wiring containing three or more conductive layers with plated-through holes, with or without stiffeners.

Type 4 — multilayer rigid-flex

Multilayer rigid and flexible material combinations (Rigid-Flex) containing three or more conductive layers with plated-through holes. Rigid-flex has conductors on the rigid layers, which differentiates it from multilayer circuits with stiffeners.

  A Type 4 rigid-flex structure; the rigid sections are formed by adding rigid layers to the outside of the flex structure.

Using rigid-flex in multi-board designs

Altium NEXUS also supports rigid-flex when designing the physical assembly board of a multi-board design. Refer to this article for more information.

Проектирование гибко-жестких плат в altium designer

Defining bends in the flex region

Once a flex Region has been created, Bending Lines can be defined in that region. A bending Line is a linear object that is placed across a region.

Defining a Bending Line:

• Bending Lines are placed in Board Planning Mode (1 shortcut).
• To place a Bending Line, run the Design » Define Bending Line command.
• Place the Bending Line across the flexible board Region. It is not necessary to precisely touch each edge of the region with the start and end of the Bending Line, the software will automatically extend it (if too short) or reduce it (if too long). At least one end of the Bending Line must touch or pass over the edge of the Region.
• To edit the properties of a Bending Line, click anywhere within the region to display the verticies for all Bending Lines within that region, then:
• To move a Bending Line, click and drag on each vertex.
• A Bending Line can be removed by clicking and holding on one of the vertices, then pressing Delete on the keyboard.
• Bending Lines cannot be applied to the edge of a board cutout. If your board requires this, switch to Rigid-Flex Advanced mode.

► Learn more about Bending Zone Definition in Standard Rigid-Flex Mode

Placing bending lines

► Learn more about Bending Zone Definition in Advanced Rigid-Flex Mode

Defining bends in the flex region (advanced mode)

A bend in a flexible section of a rigid-flex board is defined by placing a Bending Line. A bending Line is a linear object, whose properties are edited in the Bend mode of the Properties panel.