What is a stackup?
A stackup describes the arrangement and properties of the individual materials within a circuit board. The materials in the stackup must be selected depending on the area of application and the function of the circuit board. A circuit board always consists of at least one layer, if it consists of several layers, this is what we call multilayer circuit boards. An incorrectly selected stackup or the wrong materials in the stackup can lead to a circuit board not working as expected or to failure during operation.
Isolation of the copper layers
Stackups typically consist of different types of materials. The actual circuit, which connects the components on a printed circuit board with one another, is made onto a with the help of etching processes Copper layer upset. The thickness of the copper layer largely determines the current carrying capacity and the thermal conductivity. With multi-layer printed circuit boards, so-called Multilayer Assemblies, different types of materials are used to isolate the copper layers. These Material types is called Prepregs ( preimpregnated fibers ). When manufacturing the circuit board, the Prepregs placed between the copper layers and pressed together with the addition of heat. The right choice of Prepregs has a considerable influence on the thermal load capacity of the circuit board and the behavior of the circuit.
To protect the conductor tracks from corrosion, a Solder mask applied to the outside of the circuit board. This lacquer serves as protection during the soldering process and prevents short circuits from occurring. After the solder mask has been applied, only the solder contacts on the outside, onto which the later components will be soldered, are still free. In order to protect these from corrosion and to increase the solderability, a Surface treatment . The surface is sealed with different materials. For example, a thin layer of tin ( HAL ) or the contact surfaces are gold-plated ( ENIG ).
In order to create an electrical connection between two copper layers, Vias placed in the circuit board. The diameter, number and type of plated-through holes play an important role in the manufacture of the printed circuit board and largely determine the manufacturing process.
Special features of stackups or what needs to be considered
If an electronics developer creates a layout for a circuit board and uses the preset values of the CAD software used, this may result in a stackup with a thickness of 0.1 mm. If the manufacturing data is then exported and sent to a circuit board manufacturer, the question arises for him as to which materials he should use to manufacture the circuit board so that the thickness of the circuit board is actually 0.1 mm later. The following questions are also generally relevant for the printed circuit board manufacturer:
- How many layers does the stackups have? As a rule, this should be recognizable from the production data supplied. The manufacturer may interpret the data differently than the developer. Therefore, the number of layers should also be specified.
- How is the Final strength the circuit board and what is the manufacturing tolerance? Common values for the thickness are, for example, 1.0 mm or 1.6 mm.
- What are their strengths Copper layers ? In the case of multilayer stackups, the manufacturer needs information about the copper thickness of Inner layers and Outer layers . The standard copper thickness for many manufacturers is 35 μm, but for some it is 18 μm. It is therefore necessary to specify this precisely.
- Which Surface treatment is desired? Whether the surface is sealed with HAL or ENIG can make a significant difference both for the storage of the circuit board and for its use in later operation.
In order to avoid misunderstandings, the required requirements for the stackup and the materials used should be transmitted together with the production data of the circuit board.
Create and document stackups
What options does an electronics developer have to communicate the desired stackup to the manufacturer of the circuit board? What is the Best practice ?
Unfortunately, there is still no uniform standard for this. The form of documentation and communication generally depends heavily on the particular developer of the circuit board. Many developers document the stackup in the form of an additional Gerber file , a PDF document, an Excel or text file. The employee who opens the relevant file at the manufacturer has to reinterpret this file and the information it contains over and over again. This process is time consuming, both for the developer who has to create the document and for the manufacturer who has to understand and review the document. This procedure is also prone to errors, since developers and manufacturers can interpret the information differently. Unfortunately, deviations that arise here often only become apparent after the circuit board has been manufactured.
Communication between manufacturer and developer also suffers from this approach. If the manufacturer notices, for example, that the documented stackup cannot be produced in this way, he must edit the document and send it back by email.
The IPC (Institute for Printed Circuits) recommends the standardized one as a solution to the problem described IPC-2581 Format for exchanging the relevant information. It should help that developers and manufacturers have a common basis for data exchange. But not every CAD software supports the export of the layout in IPC-2581 Format. The problem of communication between developer and manufacturer also remains, in which the basis should not be a single file but rather a common data set.
So the question arises as to how the developer should communicate the required information. What is really that Best practice ?
Our solution – the StackUp module
With the StackUp module, we give electronics developers and circuit board manufacturers a common platform for exchanging information about the stackup of circuit boards. Thanks to the graphical interpretation of the stackup, manufacturers and developers see the same data and thus have the same basis for decisions. This solves the problem of communication with the help of a common platform. Electronics developers are also no longer forced to create PDF documents or Gerber files in order to communicate with the manufacturer. In addition, the time-consuming and error-prone interpretation of the data by the manufacturer is no longer necessary. As part of the Stackrate platform, the information from the StackUp module is made available to the manufacturer in digital form and can be used in any other module of the Stackrate platform.
PCB manufacturers can build up layers with the help of an extensive Material library or create and manage self-generated materials. Standard structures can be documented and made available to developers in digital form. In addition, manufacturers can give their customers access to the platform and the StackUp module. Customers can create, manage and request their own stackups with the materials approved by the manufacturer.
In order to exchange data with existing systems and software products, the stackups in the IPC-2581 Format can be imported and exported. In this way, the appropriate stackup can be selected before development begins. This enables data exchange with CAD systems such as Altium Designer , Cadence Allegro PCB Designer, Zuken and others.
If a stackup was created with the StackUp module from Stackrate, all relevant parameters such as final height, number of layers etc. are specified and the design goals can be checked. This saves both the developer and the manufacturer time and leads to an accelerated offer phase with fewer errors. If real materials from the material library were used, various DFM checks be performed. In this way, a suitable stackup can be created and checked for correct functionality before development starts.
The StackUp module is the ideal software for creating and managing complex stackups for developers and manufacturers. StackUp accelerates the creation and testing of stackups and simplifies communication between electronics developers and circuit board manufacturers.
Faster than in Excel!
Materials can be added to the materials menu in a user-friendly way. The user is provided with functions such as Copy material or stackup mirroring.
Materials can be moved within the digital stackup using drag & drop. In this way, a stackup can be created in a few seconds.
Better understandable than any PDF!
With Real View the user is given the opportunity to see the stackup as a graphic representation. The size and representation are as close as possible to the subsequent production result in order to convey a real impression of the structure during the creation and to keep an overview of the design goals at all times.
Changes in the structure or in the materials are displayed in real time.
Well organized thanks to the integrated
The basis of the stackup is the material. For this purpose, StackUp contains an existing and growing material library in cooperation with the world’s leading manufacturers for Prepregs, CCL, coverays and Copper foils .
Thanks to the integrated material management, materials can be entered or imported into the system independently. With the help of intelligent filters, the desired material can be found in seconds.
Detect errors during creation with
In principle, every stackup can be created, but not every layer structure can also be produced. With the help of an intelligent DFM analysis StackUp that Errors are recognized during the creation of the stackup and communicated to the user. In this way we ensure that all design goals can be met
An analysis is carried out automatically with every change in the stackup. This saves developers and manufacturers time and ensures a producible stackup.
“A communication solution that
Creates security. “
“I’ve failed over and over again in my life. And that is why I succeed. “
Because with complex stackups it depends on the individual material, each
Specification and every specification from the developer matters:
Use StackUp for your stackups.