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Ipc a 610 free download.IPC-AH Acceptability of Electronic Assemblies - Download -
The philosophy, implementation strategies, tools and techniques may be applied in different sequences depending on the specific company, operation, or variable under. The significant number of combinations that could occur does not allow full definition in the content and scope of this specification but manufacturers should be vigilant for the possibility of combined and cumulative conditions and their impact upon product performance.
Conditions of acceptability provided in this specification are individually defined and created with separate consideration for their impact upon reliable operation for the defined production classification. Where related conditions can be combined, the cumulative performance impact for the product may be significant; e.
The manufacturer is responsible for identification of such conditions. The User is responsible to identify combined conditions where there is significant concern based upon end use environment and product performance requirements. Where uncommon or specialized technologies are used, it may be necessary to develop unique acceptance criteria. However, where similar characteristics exist, this document may provide guidance for product acceptance criteria.
Often, unique definition is necessary to consider the specialized characteristics while considering product performance criteria. The development should include customer involvement or consent. For Class 3 the criteria shall include agreed definition of product acceptance.
Whenever possible these criteria should be submitted to the IPC Technical Committee to be considered for inclusion in upcoming revisions of this standard. It is usually the side that contains the most complex or the most number of components. This side is sometimes referred to as the component side or solder destination side in through-hole mounting technology.
This side is sometimes referred to as the solder side or solder source side in through-hole mounting technology. The solder source side is normally the secondary side of the PCB when wave, dip, or drag soldering are used. The solder source side may be the primary side of the PCB when hand soldering operations are conducted.
The destination is normally the primary side of the PCB when wave, dip or drag soldering is used. The destination side may be the secondary side of the PCB when hand-soldering operations are conducted.
Insulating material needs to provide sufficient electrical isolation. Any violation of minimum electrical clearance is a defect condition for all classes. This includes materials such as ceramic, epoxy or other composites, and flash from molded components. It is necessary that users of this standard pay particular attention to the subject of each section to avoid misinterpretation.
The inspector does not select the class for the assembly under inspection, see 1. Documentation that specifies the applicable class for the assembly under inspection shall be provided to the inspector.
Automated Inspection Technology AIT is a viable alternative to visual inspection and complements automated test equipment. Many of the characteristics in this document can be inspected with an AIT system. If the customer desires the use of industry standard requirements for frequency of inspection and acceptance, J-STD is recommended for further soldering requirement details.
All dimensions in this standard are expressed in SI System International units with Imperial English equivalent dimensions provided in brackets. Magnification aids, if used for inspection, shall be appropriate with the item being inspected. Unless magnification requirements are otherwise specified by contractual documentation, the magnifications in Table and Table are determined by the item being inspected.
Referee conditions are used to verify product rejected at the inspection magnification power. For assemblies with mixed land widths, the greater magnification may be used for the entire assembly.
Table Inspection Magnification Land Width. Note 1 Note 1: Visual inspection may require the use of magnification, e. Note 2: If magnification is used it is limited to 4X maximum.
Light sources should be selected to prevent shadows. Note: In selecting a light source, the color temperature of the light is an important consideration. When an electrostatic charge is allowed to come in contact with or close to a sensitive component it can cause damage to the component. Electrical Overstress EOS is the internal result of an unwanted application of electrical energy that results in damaged components. This damage can be from many different sources, such as electrically powered process equipment or ESD occurring during handling or processing.
Electrostatic Discharge Sensitive ESDS components are those components that are affected by these high-electrical energy surges. The relative sensitivity of a component to ESD is dependent upon its construction and materials. As components become smaller and operate faster, the sensitivity increases. ESDS components can fail to operate or change in value as a result of improper handling or processing.
These failures can be immediate or latent. The result of immediate failure can be additional testing and rework or scrap. However the consequences of latent failure are the most serious.
Even though the product may have passed inspection and functional test, it may fail after it has been delivered to the customer. It is important to build protection for ESDS components into circuit designs and packaging. In the manufacturing and assembly areas, work is often done with unprotected electronic assemblies such as test fixtures that are attached to the ESDS components.
This section is dedicated to safe handling of these unprotected electronic assemblies. Information in this section is intended to be general in nature. This unwanted electrical energy can be the result of ESD potentials or the result of electrical spikes caused by the tools we work with, such as soldering irons, soldering extractors, testing instruments or other electrically operated process equipment.
Some devices are more sensitive than others. The degree of sensitivity is a function of the design of the device. Generally speaking, higher speed and smaller devices are more susceptible than their slower, larger predecessors. The purpose or family of the device also plays an important part in component sensitivity. This is because the design of the component can allow it to react to smaller electrical sources or wider frequency ranges.
With today's products in mind, we can see that EOS is a more serious problem than it was even a few years ago. It will be even more critical in the future. When considering the susceptibility of the product, we must keep in mind the susceptibility of the most sensitive component in the assembly. Applied unwanted electrical energy can be processed or conducted just as an applied signal would be during circuit performance.
Before handling or processing sensitive components, it is important to be sure that tools and equipment will not generate damaging energy, including spike voltages. Current research indicates that voltages and spikes less than 0. However, an increasing number of extremely sensitive components require that soldering irons, solder extractors, test instruments and other equipment must never generate spikes greater than 0. As required by most ESD specifications, periodic testing may be warranted to preclude damage as equipment performance may degrade with use over time.
Maintenance programs are also necessary for process equipment to ensure the continued ability to not cause EOS damage. EOS damage is certainly similar in nature to ESD damage, since damage is the result of undesirable electrical energy. Assembly tools and materials Pressure sprays Compressed air Synthetic brushes Heat guns, blowers Copiers, printers. Walking on carpet 35, volts 1, volts Walking on vinyl flooring 12, volts volts Worker at a bench 6, volts volts Vinyl envelopes Work Instructions 7, volts volts Plastic bag picked up from the bench 20, volts 1, volts Work chair with foam pad 18, volts 1, volts The best ESD damage prevention is a combination of preventing static charges and eliminating static charges if they do occur.
All ESD protection techniques and products address one or both of the two issues. ESD damage is the result of electrical energy that was generated from static sources either being applied or in close proximity to ESDS devices.
Static sources are all around us. The degree of static generated is relative to the characteristics of the source. To generate energy, relative motion is required. This could be contacting, separation, or rubbing of the material. Most of the serious offenders are insulators since they concentrate energy where it was generated or applied rather than allowing it to spread across the surface of the material.
See Table Peeling adhesive tape from a roll can generate 20, volts. Even compressed air nozzles that move air over insulating surfaces generate charges.
Destructive static charges are often induced on nearby conductors, such as human skin, and discharged into conductors on the assembly. This can happen when a person having an electrostatic charge potential touches a printed board assembly.
The electronic assembly can be damaged as the discharge passes through the conductive pattern to an ESDS component. Electrostatic discharges may be too low to be felt by humans less than static volts , and still damage ESDS components.
Typical static voltage generation is included in Table Examples of frequently encountered labels are shown in Figure Symbol 1 ESD susceptibility symbol is a triangle with a reaching hand and a slash across it. This is used to indicate that an electrical or electronic device or assembly is susceptible to damage from an ESD event.
Figure E Fig 1. ESD Susceptibility Symbol 2. This is used to identify items that are specifically designed to provide ESD protection for ESD sensitive assemblies and devices. Symbols 1 and 2 identify devices or an assembly as containing devices that are ESD sensitive, and that they must be handled accordingly.
Note that the absence of a symbol does not necessarily mean that the assembly is not ESD sensitive. When doubt exists about the sensitivity of an assembly, it must be handled as a sensitive device until it is determined otherwise.
This protection could be conductive static-shielding boxes, protective caps, bags or wraps. ESDS items must be removed from their protective enclosures only at static safe workstations. It is important to understand the difference between the three types of protective enclosure material: 1 static shielding or barrier packaging , 2 antistatic, and 3 static dissipative materials. Static shielding packaging will prevent an electrostatic discharge from passing through the package and into the assembly causing damage.
Antistatic low charging packaging materials are used to provide inexpensive cushioning and intermediate packaging for ESDS items.
Antistatic materials do not generate charges when motion is applied. Static dissipative materials have enough conductivity to allow applied charges to dissipate over the surface relieving hot spots of energy. Do not be misled by the "color" of packaging materials. It is widely assumed that "black" packaging is static shielding or conductive and that "pink" packaging is antistatic in nature.
While that may be generally true, it can be misleading. In addition, there are many clear materials now on the market that may be antistatic and even static shielding. This is not necessarily the case now. Caution: Some static shielding and antistatic materials and some topical antistatic solutions may affect the solderability of assemblies, components, and materials in process.
Solvent cleaning of static dissipative or antistatic surfaces can degrade their ESD performance. Follow the manufacturer's recommendations for cleaning. Safe workstations should include EOS damage prevention by avoiding spike generating repair, manufacturing or testing equipment. Soldering irons, solder extractors and testing instruments can generate energy of sufficient levels to destroy extremely sensitive components and seriously degrade others.
For ESD protection, a path-to-ground must be provided to neutralize static charges that might otherwise discharge to a device or assembly. Provisions are also made for grounding the worker's skin, preferably via a wrist strap to eliminate charges generated on the skin or clothing.
Provision must be made in the grounding system to protect the worker from live circuitry as the result of carelessness or equipment failure. This is commonly accomplished through resistance in line with the ground path, which also slows the charge decay time to prevent sparks or surges of energy from ESD sources. Additionally, a survey must be performed of the available voltage sources that could be encountered at the workstation to provide adequate protection from personnel electrical hazards.
For maximum allowable resistance and discharge times for static safe operations, see Table Floor mat to ground megohms less than 1 sec. Table mat to ground megohms less than 1 sec. Wrist strap to ground megohms less than 0. Note: The selection of resistance values is based on the available voltages at the station to ensure personnel safety as well as to provide adequate decay or discharge time for ESD potentials.
Examples of acceptable workstations are shown in Figures and When necessary, air ionizers may be required for more sensitive applications. The selection, location, and use procedures for ionizers must be followed to ensure their effectiveness Figure Series Connected Wrist Strap E Fig 1. Personal wrist strap 2. EOS protective trays, shunts, etc.
EOS protective table top 4. EOS protective floor or mat 5. Building floor 6. Common ground point 7. Ground Keep workstation s free of static generating materials such as Styrofoam, plastic solder removers, sheet protectors, plastic or paper notebook folders, and employees' personal items.
Tools and equipment must be periodically checked and maintained to ensure proper operation. Note: Because of the unique conditions of each facility, particular care must be given to "third wire" ground terminations.
Frequently, instead of being at workbench or earth potential, the third wire ground may have a "floating" potential of 80 to volts. Most ESD specifications also require these potentials to be electrically common. Whatever comes in contact with these surfaces must be clean. When boards are removed from their protective wrappings, handle them with great care.
Touch only the edges away from any edge connector tabs. These principles are especially critical when no-clean processes are employed. Care must be taken during assembly and acceptability inspections to ensure product integrity at all times. Table provides general guidance.
Printed circuit boards and commonly used plastic components absorb and release moisture at different rates. During the soldering process heat causes expansion of the moisture which can damage the ability of the materials to perform as required for the product requirements. This damage crack, internal delamination, popcorning may not be visible and can occur during original soldering as well as during rework operations.
To prevent laminate issues, if the level of moisture is unknown, PCBs should be baked to reduce the internal moisture content. The baking temperature selection and duration should be controlled to prevent reduction of solderability through intermetallic growth, surface oxidation or other internal component damage.
Keep workstations clean and neat. There must not be any eating, drinking, or use of tobacco products in the work area. Minimize the handling of electronic assemblies and components to prevent damage. When gloves are used, change as frequently as necessary to prevent contamination from dirty gloves. Do not handle solderable surfaces with bare hands or fingers. Body oils and salts reduce solderability, promote corrosion.
They can also cause poor adhesion of subsequent coatings or encapsulates. Do not use hand creams or lotions containing silicone since they can cause solderability and conformal coating adhesion. Never stack electronic assemblies or physical damage may occur. Special racks may be provided in assembly areas for. Always assume the items are ESDS even if they are not marked.
Personnel must be trained and follow appropriate ESD practices and procedures. Never transport ESDS devices unless proper packaging is applied 3. Physical damage of this type can ruin the entire assembly or attached components.
Body oils and acids can reduce solderability, promote corrosion and dendritic growth. They can also cause poor adhesion of subsequent coatings or encapsulants. Normal cleaning procedures may not remove all contaminants. Therefore it is important to minimize the opportunities for contamination. The best solution is prevention. Frequently washing ones hands and handling boards only by the edges without touching the lands or pads will aid in reducing contamination.
When required the use of pallets and carriers will also aid in reducing contamination during processing. The use of gloves or finger cots many times creates a false sense of protection and within a short time can become more contaminated than bare hands. When gloves or finger cots are used they should be discarded and replaced often.
Gloves and finger cots need to be carefully chosen and properly utilized. Many sensitive assemblies will also be marked on the assembly itself, usually on an edge connector. To prevent ESD and EOS damage to sensitive components, all handling, unpacking, assembly and testing shall be performed at a static controlled workstation see Figures and Fingerprints are extremely hard to remove and will often show up in conformally coated boards after humidity or environmental testing.
Gloves or other protective handling devices may be used to prevent such contamination. Use mechanical racking or baskets with full ESD protection when handling during cleaning operations.
This damage could be in the form of latent failures, or product degradation not detectable during initial test or catastrophic failures found at initial test. This section is primarily concerned with visual assessment of proper securing tightness , and also with damage to the devices, hardware, and the mounting surface that can result from hardware mounting. Process documentation drawings, prints, parts list, build process will specify what to use; deviations need to have prior customer approval.
Note: Criteria in this section do not apply to attachments with self-tapping screws. Visual inspection is performed in order to verify the following conditions: a. Correct parts and hardware. Correct sequence of assembly. Correct security and tightness of parts and hardware. No discernible damage. Correct orientation of parts and hardware. The following topics are addressed in this section: 4. Figure 1. Metallic hardware 2.
Conductive pattern 3. Specified minimum electrical clearance 4. Mounted component 5. Spacing less than electrical clearance requirements 4. Bonding with thermally conductive adhesives may be specified in place of hardware. Visual inspection includes hardware security, component damage, and correct sequence of assembly. The following additional issues shall be considered: The component has good contact with the heatsink. The hardware secures the component to the heatsink.
The component and heatsink are flat and parallel to each other. Acceptable - Class 1, 2, 3 Not uniform but evidence of mica, plastic film or. Acceptable - Class 1, 2, 3 Component not flush. Hardware meets mounting torque requirements if. Figure is an example of this kind of lock washer. Unless otherwise specified the sharp edges of the lock washer should be against the flat washer. Thread extension more than 3 mm [0. Thread extension more than 6. Bolts or screws without locking mechanisms extend less than one and one half threads beyond the threaded hardware.
Lock washer, sharp edge showing towards flat washer 2. Flat washer 3. Nonconductive material laminate, etc. Metal not conductive pattern or foil. Lock washer, sharp edge towards flat washer 2. Solder lug Figure 1.
Slot or hole 2. Lock washer 3. Flat washer. Flat washer missing, Figures , Hardware missing or improperly installed, Figure. Defect - Class 1, 2, 3 Lock washer not compressed. Fastener torque value, if specified, is not within.
Unless otherwise noted, all requirements apply to both stranded and solid wires. Wire end secured under screw head. Wire wrapped in the correct direction. All strands are under screw head. Lock washer 2. Nonmetal 3.
Metal not conductive pattern or foil Figure Figure 1. Lock washer. Mechanical attachment of the wire is in contact between the screw head and the contact surface for a minimum of around the screw head. No insulation in the contact area.
Wire does not overlap itself. Defect - Class 1, 2, 3 Wire not wrapped around screw body A. Insulation in the contact area E.
Stranded wire is tinned not shown. Missing solder or adhesive as required per. This is critical to obtain maximum connector pin contact. Hardware stack-up for mounted connectors may be varied in order to locate the face of the jackpost flush to 0. Installation of these devices is usually done with automated equipment.
Visual inspection of this mechanical operation includes: correct pins, damaged pins, bent and broken pins, damaged spring contacts and damage to the substrate or conductive pattern.
For connector mounting criteria see 7. For connector damage criteria see 9. Acceptable - Class 1, 2, 3 Gap is within specified tolerance.
Contact is contained within the insulator. Note: To provide allowance for an extraction tool, the gap between the contact shoulder and the land needs to be adequate for each manufacturer's repair tooling. Defect - Class 1, 2, 3 Contact is above insulator A. Gap between contact shoulder and land is greater.
Target — Class 1, 2, 3 Pins are straight, not twisted and properly seated. Note: Nominal height tolerance is per pin connector or master drawing specification. The connector pins and mating connector must have a good electrical contact. Backplane 2. Land 3. Shoulder 4.
Contact 5. Gap 6. No land damage 7. No discernible damage 8. Pin visibly twisted. Pin height is out of tolerance as to specification. Acceptable — Class 1, 2, 3 No lifted or fractured annular rings with press fit. Acceptable — Class 2 No visual evidence of lifted land on insertion side. Acceptable — Class 3 No lifted or fractured annular rings.
Defect - Class 1, 2 Any protrusion side functional land lifted more. Defect — Class 2 Any evidence of lifted lands on the insertion side. Defect - Class 3 Any lifted or fractured annular rings with press fit. If soldering is required the following criteria is applicable. Land with conductor 3. Land not fractured 4. Land lifted, fractured but firmly attached land without conductor nonfunctional.
Land fractured 2. Land lifted. Acceptable — Class 3 A solder fillet is evident on the secondary. Gizzly Tipon. Akash Gautam. Shahrul Amri. Trieu Hanh Tran. Yinpo Hung. John Easton. Denis Jean. Ning-Cheng Lee. Jocelyn Siplon. Zohreh Bagheri. Raiyo Aspandiar. Ross Wilcoxon. Nathan Blattau. Ioan Plotog.
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