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IPC/WHMA-AB Redline Document - PDF Drive. Ipc whma a 620a free download
Ipc whma a 620a free download
IPC/WHMA-A : Requirements and Acceptance for Cable and Wire Harness Assemblies. Ipc whma a 620a free download
Standards may be updated at any time, including with the use of amendments. The use of an amendment or newer revision is not automatically required. The revision in effect shall [D1D2D3] be as specified by the User. Read more… Read less…. Prices subject to change without notice. About Us. Contact Us. Sign In. Purchase History. Currency display settings. Manage society memberships. Featured Products.
View All Publishers. Quality Management. SCC Standards Store. Popular Standards Bundles. Drawing and Drafting. Telecommunications Standards. Space addendum for B course materials is available! A global trade association dedicated to the competitive excellence and financial success of its more than 3, member companies, IPC represents all facets of the industry including design, printed circuit board manufacturing and electronics assembly.
Any method that produces an assembly conforming to the acceptability requirements described in this standard may be used. The User has the ultimate responsibility for identifying the Class to which the assembly is evaluated.
When major elements of the proven processes are changed e. Limited shelf life items shall [D1D2D3] be stored and controlled in accordance with material manufacturer s recommendations, or in accordance with the Supplier s documented procedures for controlling shelf life and shelf life The material specification or other documented procedure shall [D1D2D3] be followed for mixing and curing.
Material shall [D1D2D3] be used within the pot life working time specified by the material supplier or used within the time period indicated by a documented system. When curing conditions temperature, time, infrared IR intensity, etc. Equipment used for measuring viscosity, mixing, applying and curing silicone material shall not [D1D2D3] be used for processing other material Figures and Illustrations Many of the examples figures shown are grossly exaggerated to clearly depict the condition being described.
In the case of a discrepancy, the written description or written criteria always takes precedence over the illustrations Defects and Process Indicators Characteristics or conditions that do not conform to the requirements of this standard that are detectable by inspection or analysis are classified as either defects or process indicators. Not all process indicators are specified by this standard. Process indicators should be monitored but the hardware needs not be dispositioned, see It is the responsibility of the user to define unique defect categories applicable to the product.
It is the responsibility of the manufacturer to identify defects and process indicators that are unique to the assembly process Inspection Conditions For each section of this document, target, acceptable and defect conditions are listed for each product class. Where applicable, process indicator conditions are also listed.
The inspector shall not [D1D2D3] select the product class for the assembly under inspection. Documentation that specifies the applicable class for the assembly under inspection shall [D1D2D3] be provided to the inspector. The descriptions of these conditions follow Target A condition that is close to perfect in the past has sometimes been labeled as "preferred.
It is a desirable condition, not always achievable, and may not be necessary to ensure reliability of the assembly in its service environment Acceptable This characteristic indicates a condition that, while not necessarily perfect, will maintain the integrity and reliability of the assembly in its service environment Process Indicator A process indicator is a condition not a defect that identifies a characteristic that does not affect the form, fit, function or reliability of a product.
Process indicators should be monitored as part of the process control system. If the number of process indicators indicates an abnormal variation in the process, identifies an undesirable trend, or displays other conditions that indicate the process is or is approaching out of control, the process shall [N1N2D3] be analyzed. This may result in action to reduce the variation and improve yields. Disposition of individual process indicators is not required and affected product should be used as is.
It is the responsibility of the manufacturer to identify process indicators that are unique to the assembly process Defect A defect is a condition that fails to meet the acceptance criteria of this document and negatively affects the form, fit or function, of the assembly in its end use environment. The manufacturer shall [DN1D2D3] document and disposition each defect. It is the responsibility of the user to define unique defect categories applicable to the product Disposition Disposition is the determination of how defects should be treated.
Dispositions include, but are not limited to, rework, use as is, scrap or repair. A defect for a Class 2 product means that the characteristic is also a defect for a Class 3 product, but may not be a defect for a Class 1 product where less demanding criteria may apply Conditions Not Specified Conditions that are not specified as defective or as a process indicator are considered acceptable unless it can be established that the condition affects end user defined form, fit, function or reliability Electrical Clearance Electrical clearance spacing between conductors should be maximized whenever possible.
The minimum spacing between conductors and between conductive materials such as conductive markings or mounting hardware and conductors should be defined on the applicable drawings or documentation. When mixed voltages appear on the same assembly, the specific areas and appropriate clearances should be identified on the drawings. Violation of minimum electrical clearance isshall [D1D2D3] be a defect.
The minimum electrical clearance distance depends on the circuit voltage rating and the normal volt-ampere rating. In cases where no minimum electrical clearance value is otherwise defined, the criteria in Table may be used as a guideline.
Supplemental lighting may be necessary to assist in visual inspection. Light sources should be selected to prevent shadows on the item being inspected except those caused by the item being inspected. Light ranges from K enable users to distinguish various metal and plating features and contaminants with increased clarity Magnification Aids and Lighting When required, magnification power for assembly inspection shall [A1P2D3] be at least the minimum inspection power specified in Table Other magnification powers within the inspection range may be used.
The magnification power requirement is based on the gauge of the wire being inspected. For assemblies with mixed wire sizes, the greater magnification may be used for the entire assembly. If the presence of a defect cannot be determined at the inspection power, the item is acceptable. The referee magnification power is intended for use only after a defect has been determined but is not completely identifiable at the inspection power.
Supplemental lighting may be necessary to assist in visual assessment. See 4. Handling of cleaned assemblies shall [N1N2D3] preclude recontamination. Rework shall [D1D2D3] meet all applicable requirements of this standard. Rework does not include a second application of a soldering iron during a hand soldering operation on a single connection Repair Repairs shall [N1D2D3] be conducted in accordance with a documented procedure.
The repair method shall [N1N2D3] be determined by agreement between the manufacturer and the user. Training is provided to personnel with assigned responsibilities in the development, implementation, and utilization of process control and statistical methods that are commensurate with their responsibilities. Quantitative methodologies and evidence is maintained to demonstrate that the process is capable and in control.
Improvement strategies define initial process control limits and methodologies leading to a reduction in the occurrence of process indicators in order to achieve continuous process improvement. Criteria for switching to sample based inspection is defined. Chemical insulation stripping agents shall [D1D2D3]: Be used only for solid wires.
Be neutralized or removed prior to tinning or soldering. The number of damaged scraped, nicked or severed strands in a single wire shall not [D1D2D3] exceed the limits of Table As an exception to Table Partial or incomplete cuts of strand groups shall not [A1A2D3] be in the crimp contact area. Partial cuts of a strand group shall not [A1A2D3] be in a solder connection area or prevent contact of the strand group for the full length of the required wrap.
Note: See Tools utilized to accomplish wire cuts shall [N1D2D3] be selected and used to provide repetitive and consistent wire cut terminations that meet the following criteria. The process of wire cutting shall [N1D2D3] be performed such that the cut ends are uniform and all strands are the same length. Figure A Fig Target Class 1, 2, 3 Wire conductor ends are cut perpendicular to the wire longitudinal axis.
All of the strands of the strand group are the same length. Wires are not scraped, nicked, cut, flattened, scored, or otherwise damaged. All of the strands of the strand group are approximately the same length. There are attached burrs that will not be dislodged during process or operation. Acceptable - Class 1 Process Indicator - Class 2,3 Strands cut, broken, scraped or severed if the number of damaged or broken strands in a single wire does not exceed the limits in Table Figure A Fig Defect - Class 1, 2, 3 Variation in strand length within a strand group that prevents installation to the full depth of the crimp contact area.
Damaged strands exceed the limits specified in Table As an exception to Table , partial cuts of a strand group that are in a solder connection area or could prevent contact of the strand group for the full length of the required wrap. Note 2: For plated wires, a visual anomaly that does not expose basis metal is not considered to be strand damage. Figure A Fig Target Class 1, 2, 3 Strands are not flattened, untwisted, buckled, kinked or otherwise deformed.
Original lay of strands is not disturbed. Figure A Fig Acceptable Class 1, 2, 3 Wire strands have separation birdcaging, shown by arrow and do not extend beyond wire insulation outside diameter. Wire strands have separation birdcaging, shown by arrow but: do not exceed one strand diameter. Where strands were straightened during the wire insulation removal, they have been restored to approximate the original spiral lay of the wire.
Wire strands are not kinked. Figure A Fig Acceptable Class 1 Process Indicator Class 2 Defect Class 3 Wire strands have separation exceeding 1 strand diameter but do not extend beyond wire insulation outside diameter. Acceptable Class 1 Defect Class 2,3 The general spiral lay of the strands has not been maintained. Acceptable Class 1 Defect Class 2,3 Wire strands extend beyond wire insulation outside diameter. Defect Class 1,2,3 Wire strands are kinked. The length of lay or "twist" as measured from the midpoint of wire's crossover through a complete spiral to the next crossover midpoint of the same wire shall [D1D2D3] be 8 to 16 times the outer diameter of the bundle Figure Figure A Fig Acceptable Class 1,2,3 The length of lay for each twist is 8 to 16 times the outer diameter of the bundle.
Figure A Fig Defect Class 1,2,3 The length of lay for each twist is less than 8 or more than 16 times the outer diameter of the bundle. These criteria are also applicable to post-assembly acceptance. Additional criteria for insulation damage as a result of soldering operations are provided in Figure A Fig Target - Class 1,2,3 Insulation has been trimmed neatly with no signs of pinching, pulling, fraying, discoloration, charring or burning. Figure A Fig Acceptable - Class 1,2,3 A slight, uniform impression in the insulation from the gripping of mechanical strippers.
Chemical solutions, paste, and creams used to strip solid wires do not cause degradation to the wire. Slight discoloration of insulation resulting from thermal processing is permissible, provided it is not charred, cracked or split. Insulation is charred Figure Criteria for forming soldered splices are provided in Section 8. Criteria for heat shrinkable solder sleeves are provided in Sections 8 Splices and 15 Shield Terminations. When major elements of the proven processes are changed, e.
Flux that is part of flux-cored solder wire [D1D2D3] meet the requirements of Flux percentage is optional. Solder alloys less than 0. When other activity levels or flux materials are used, data demonstrating compatibility shall [N1N2D3] be available for review. Note: Flux or soldering process combinations previously tested or qualified in accordance with other specifications do not require additional testing.
When an external flux is used in conjunction with flux cored solders, the fluxes shall [D1D2D3] be compatible Material, Components and Equipment - Materials - Adhesives Electrically nonconductive adhesive materials used for attachment of components should conform to an acceptable document or standard, e. The adhesives selected shall not [D1D2D3] be detrimental to the component or assembly they are used on.
The material shall [D1D2D3] be cured. When a solderability inspection operation or pretinning and inspection operation is performed as part of the documented assembly process, that operation may be used in lieu of solderability testing.
The manufacturer should establish procedures to minimize part solderability degradation. A wire or terminal not conforming to the solderability requirements may be reworked e. Soldering irons, equipment, and systems shall [D1D2D3] provide appropriate temperature control and isolation from electrical overstress or ESD. These requirements may be eliminated if there is documented objective evidence available for review that there are no gold related solder embrittlement problems associated with the soldering process being used.
Flux residue can degrade product performance over time based upon environmental conditions. Methods and materials that are used to clean soldered assemblies shall [D1D2D3] be compatible with the product and assembly materials so that the cleaning process does not adversely affect performance characteristics.
Solder connections produced using no-clean processes need only be cleaned when required. Defect - Class 1,2,3 Dirt and particulate matter on assembly, e.
Defect Class 1,2,3 Visible flux residue Cleanliness - Postsoldering - Flux Residue No-Clean Process Flux residue may be present if it is flux residue that is not intended to be cleaned.
No illustrations. Flux residue does not inhibit access to test points of the assembly. No-clean flux residue on any electrical mating surface. There are specialized soldering finishes, e. The criteria should be based on design, process capability and performance requirements.
The acceptable solder connection must indicate evidence of wetting and adherence where the solder blends to the soldered surface. This standard provides visual criteria for inspection of both tinlead and lead-free connections.
Figures specific to lead-free connections will be identified with the symbol: Acceptable lead-free and tin-lead connections may exhibit similar appearances but lead free alloys are more likely to have: Surface roughness grainy or dull. Greater wetting contact angles. All other solder fillet criteria are the same. Typical tin-lead connections have from a shiny to a satin luster, generally smooth appearance and exhibit wetting as exemplified by a concave meniscus between the objects being soldered.
High temperature solders may have a dull appearance. Touch-up rework of soldered connections is performed with discretion to avoid causing additional problems, and to produce results that exhibit the acceptability criteria of the applicable class. Undesirable wetting conditions are typically nonwetting and dewetting. Nonwetting is characterized as partial adherence of solder to a surface that it has contacted and basis metal remains exposed.
Dewetting is a condition where molten solder coats a surface and then recedes to leave irregularly shaped mounds of solder on the surface that are separated by areas covered with a thin film of solder and without leaving basis metal exposed. Some solders may have a dull appearance e. These should not be considered defective based upon their surface appearance.
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