Documentation Requirements for Printed Boards, Assemblies and Support Drawings
|Publication Date:||1 May 1995|
This standard establishes requirements and other considerations for the documentation of printed boards and printed board assemblies.
The purpose of this standard is to establish the general requirements for the preparation of drawings necessary to fully describe end product printed boards, printed board assemblies and related support drawings. Special emphasis is given to the technical requirements necessary to fully describe the fabrication and assembly of various types of printed boards. Regardless of material, construction, layer count, special fabrication requirements, or end product usage, the documentation package may include, but not be limited to the following:
• Master Drawing Requirements
• Board Definition
• Soldermask Requirements
• Master Pattern Drawing
• Production Master
• Assembly Drawing and Parts List
• Electrical Test Requirements
• Final Schematic/Logic Diagram
• Related Support Drawings
• Artwork Plot Data
• Excellon Drill Data
Refer to IPC-D-275, "Design Standard for Rigid Printed Boards and Rigid Printed Board Assemblies," regarding all subjects pertaining directly to design.
This standard may be used for both commercial and military applications. Printed boards and printed board assemblies intended for military usage shall be fabricated and/or assembled by a manufacturer that has been qualified to the appropriate military specification, unless otherwise agreed to contractually.
Documentation intended for military electronic equipment shall be so noted.
Organization of Information
This standard is organized into various sections in order to provide information for the documentation of rigid printed boards and printed board assemblies.
The major sections and their specific emphasis are:
Section 1 − Scope, Purpose and Classification
Section 2 − Applicable Documents
Section 3 − Documentation Requirements
Section 4 − Documentation Package
Section 5 − Sample Figures and Examples
Section 6 − Master Drawing Notes and Check List
Section 7 − Design Outputs
Section 8 − Printed Board Assembly Drawings (Including Figures & Examples)
Section 9 − Printed Board Support Drawings
Section 10− Schematic / Logic Diagrams
This standard recognizes that rigid printed boards and printed board assemblies are subject to classifications by intended end item use. Classification of producibility is related to complexity of the design and the precision required to produce the particular printed board or printed board assembly.
Any producibility level or producibility design characteristic may be applied to any end-product equipment category. Therefore, a high-reliability product designated as class "3" (see 1.2.2), could require level "A" design complexity (preferred producibility) for many of the attributes of the printed board or printed board assembly (see 1.2.3).
This standard provides design information for different board types. Board types are classified:
Type 1 − Single-Sided Printed Board
Type 2 − Double-Sided Printed Board
Type 3 − Multilayer Board without Blind or Buried Vias
Type 4 − Multilayer Board with Blind and/or Buried Vias
Type 5 − Multilayer Metal-Core Board without Blind or Buried Vias
Type 6 − Multilayer Metal-Core Board with Blind and/or Buried Vias
Three general end-product classes have been established to reflect progressive increases in sophistication, functional performance requirements and testing/inspection frequency. It should be recognized that there may be an overlap of equipment between classes.
The printed board user is responsible for determining the class in which his board product belongs.
Class 1 - General Electronic Products
Includes consumer products, some computer and computer peripherals, as well as general military hardware suitable for applications where cosmetic imperfections are not important and the major requirement is function of the completed printed board or printed board assembly.
Class 2 - Dedicated Service Electronic Products
Includes communications equipment, sophisticated busi-ness machines, instruments and military equipment where high performance and extended life is required, and for which uninterrupted service is desired but is not critical. Certain cosmetic imperfections are allowed.
Class 3 - High Reliability Electronic Products
Includes the equipment for commercial and military prod-ucts where continued performance or performance on demand is critical. Equipment downtime cannot be tolerated, and must function when required such as for life support items, or critical weapons systems. Printed boards and printed board assemblies in this class are suitable for applications where high levels of assurance are required and service is essential.
When appropriate, this standard will provide three levels of design complexity: Levels A, B, and C. Included are special features, tolerances, measurements, assembly, testing of completion, and verification of the manufacturing process. Higher levels of design complexity often result in a reduction of the productibility level and, therefore, increased fabrication costs. These levels are:
Level A - General Design Complexity-Preferred
Level B - Moderate Design Complexity-Standard
Level C - High Design Complexity-Reduced Producibility
The producibility levels are not to be interpreted as a design requirement, but a method of communicating the degree of difficulty of a feature between design and fabrication/assembly
This standard provides three classes for documentation requirements to reflect progressive increases in sophistication of the draw-ing package. The three classes of documentation are:
Class A - Minimal Documentation
Class B - Moderate Documentation
Class C - Full Documentation
Selection of class should be based on the minimum need, recognizing that less sophisticated classes require more coordination and communication between user and vendor. Requirements for documentation shall be specified in the contract order used to procure documentation, equipment or both.
Note: Classification of documentation requirements should not be confused with the classification of end item use, as referenced in other IPC standards and specifications which refer to: Class 1) consumer products; Class 2) general industrial; and Class 3) high reliability equipment. The need to apply documentation practices to a particular class of equipment should depend on the complexity of the interface required to produce the printed board; therefore, any documentation class may be applied to any of the end product equipment categories (classes) as required; examples: Class 2B would be industrial equipment supported by moderate documentation.
There are three classes of documentation requirements. These requirements reflect the differences in sophistication and completeness of the documentation packages. The three classes are defined as follows:
Class A - Minimal Documentation
This class of documentation is identified as minimal and consists of layout and artwork only. Class A documentation is usually used for internal use and requires a good deal of coordination between the user and manufacturer of the board. Information may be incomplete in some instances and relies heavily on in-house agreed to manufacturing processes, such as standard material, standard plating processes, standard tolerances, etc.
Documentation is suitable for the application, where the only requirement is that the manufacturer can produce a functional product from information supplied. It may include, as a minimum, the designer's layout or check plot containing manufacturing notes/instructions and single image artwork master.
Class B - Moderate Documentation
Class B documentation package consists of complete board definition, without any description of the manufacturing allowances that have been incorporated into the design. Contractual drawing requirements may apply. Quality conformance coupons may be defined by the design; their position in relationship to the board or the manufactured panel is optional.
The Class B documentation package requires sufficient clarity such that the information may be reviewed by a board manufacturer, in order to establish product producibility using the artwork or other tooling supplied. Since Class B documentation is manufacturer sensitive, responsibility for various aspects of the manufacturing cycle shall be agreed to between user and fabricator.
Class B documentation is specifically prepared to convey maximum information to the manufacturer and includes: a master drawing, all manufacturing notes and a single or multiple image artwork master. Performance specifications may be referenced, and contractual drawing requirements may be applied.
Class C - Full Documentation
Class C is a fully documented procurement package. Documentation is to the extent that the information is self-sufficient and may be sent to multiple vendors, with each producing the identical product. This documentation package requires that the full manufacturing allowances are disclosed and documented. Quality conformance coupons are mandatory, as required by the design, with the location illustrated on the master drawing and artwork establishing the relationship between coupons and the board.
Class C documentation includes a formal master drawing and may include a single/multiple image production master, magnetic tape, NC instructions, reference to material requirements, dielectric constant, glass style resin content, etc.; electrical test data, performance testing and sampling plan call outs. In addition, contractual drawing requirements may apply.