IPC 7711/7721 Revision BRework, Modification & Repair of Electronic Assemblies

Peggi BlakleyNSWC-Crane DivisionDepartment of the Navy7-34 co-chair

Peggi has worked in the Electronics Rework and Repair Field for more than 35 years. She has spent the past 25 years working with the United States Navy’s 2M program. The 2M Program provides the technical requirements, curriculum development as well as procedures and logistic support for rework and repair performed on circuit card assemblies and electronics modules in the field and aboard ship by Navy, Marine Corps, Air Force and Coast Guard personnel. Peggi is the Industry Liaison for Naval Surface Warfare Center, Crane and serves on many of the IPC assembly and joining committees. She is the 5-21a Component Mounting Task Group chair and has served as co-chair of the IPC-7711/7721 since 1994.

7-34 Repairability Subcommittee

• Leadership– Peggi Blakley, NSWC Crane– Dan Foster, STI Electronics

• Charter– This subcommittee overseas all repair and modification standards activity.

Repairability Documents

• IPC-7711 Rework of Electronic Assemblies

• IPC-7721 Repair and Modification of Printed Boards and Electronic Assemblies

REVISION B• IPC-7711/7721 Rework,

Modification and Repair of Electronic Assemblies

Part 1 Section 1

• Extensive changes• Most important part of IPC-7711/7721

• Tells how to use the document!

It’s #1 for a reason!

1 Scope

• Added important statement:

This document does not limit the maximum number of rework, modification or repair actions to a printed circuit board assembly.

Rework – Modification – Repair

• Modification – the revision of the functional capability of a product in order to satisfy new acceptance criteria. Modifications are usually required to incorporate design changes which can be controlled by drawings, change orders, etc.

Rework – Modification – Repair

• Rework – the act of reprocessing non-complying articles, through the use of original or equivalent processing, in a manner that assures full compliance of the article with applicable drawings or specifications.

Rework – Modification – Repair

• Repair – the act of restoring the functional capability of a defective article in a manner that does not assure compliance of the article with applicable drawings or specifications.

Don’t dwell on the terms

• When using this document, call the action whatever you want but the procedures meeting the IPC definitions of rework are in Part 2 and modification/repair are in Part 3.

• General procedures and “how to use the book” are in Part 1

Procedure HeaderRework

Procedure

ProcedureNumberProcedure

Title

Examples of tools used for this Procedure

Information from Section 1 to help users select the appropriate Procedure

Examples of components

Board Types 1.4.4

R Rigid Printed Boards & Assemblies

F Flexible Printed Boards & Assemblies

W Discrete Wiring Boards & Assemblies

C Ceramic Boards & Assemblies

Skill Level 1.4.6

I Intermediate – Technician with skills in basic soldering and component rework but inexperienced in general repair/rework procedures.

A Advanced – Technician with soldering and component rework skills and exposure to most repair/rework procedures but lacking extensive experience.

E Expert – Technician with advanced soldering and component rework skills and extensive experience in most repair/rework procedures.

Level of Conformance 1.4.5

L Lowest Level – Significant variance with the physical character of the original and may vary with many of the electrical, functional, environmental and serviceability factors.

M Medium Level – Some variance with the physical character of the original and most likely varies with some of the functional, environmental and serviceability factors.

H Highest Level – Most closely duplicates the physical characteristics of the original and most probably complies with all the functional, environmental and serviceability factors.

Level of Conformance 1.4.5.2

• In the absence of other defined acceptability criteria the reworked product needs to comply with the visual acceptance criteria of IPC-A-610.– This is applicable to rework operations and some portions of modification actions

–Not applicable to repair

Repair Acceptance 1.4.2.2

• Modification and repair, by their nature, do not have industry established requirements and acceptance criteria.

• These will need to be determined on a case by case basis.

5.3 Plated Hole RepairINSPECTION GUIDELINES1. Visual examination, dimensional requirement

of pad diameter and inside diameter.2. Electrical continuity measurement.3. Proper alignment of eyelet to hole.4. No epoxy on solderable surfaces or that

interferes with minimum solder requirements.5. Eyelet flange does not violate minimum

electrical clearance.6. Conductor damage.7. Board damage.

Appropriate Approvals 1.7 (1)

• When rework, repair, or modification of newly manufactured products is conducted, appropriate approvals may be required. Unless prohibited by the customer, rework of newly manufactured products may be performed without prior approval of the customer. Repair actions generally require prior approval by the customer. Modification may require prior approval of the customer.

• NOTE THAT THIS DOCUMENT DOES NOT PROVIDE “APPROVAL” FOR ANY ACTION.

Patience 1.7 (5)

• To achieve best results, do not rush the process.

• Keep in mind that most of the cost for fabrication/assembly has already been spent, but with care and patience, most of this cost can be salvaged.

Workstations, Tools, Materials and Processes

1.8• The use of proper tools and supplies, many unique to repair actions, will often have a significant impact on the function and reliability of the end product.

• To enhance the ease of the task at hand and to improve the potential for a successful operation, the following guidelines in the header should support all operations identified in paragraph 1.8

Workstations, Tools, Materials and Processes

1.8• 1.8.14 Process Goals- and Guidelines • 1.8.14.1 Non-destructive Component Removal

• 1.8.14.1.1 Surface Mount Components• 1.8.14.1.2 Through-Hole Components• 1.8.14.1.3 Component Removal Using Solder Fountain Method

• 1.8.14.2 Component Installation• 1.8.14.2.1 Land Preparation• 1.8.14.2.2 Surface Mount Components• 1.8.14.2.3 Through-Hole Components

Lead-Free 1.9

• The rework of circuit boards assembled using lead free solders is similar to common alloys except as noted…

• The procedures in this document are not specific to any alloy type and should be compatible with most commonly used tin-lead or lead-free alloys.

Lead-Free 1.9

• When effecting repair of fielded assemblies, it may be impossible to determine the alloy type

• When unknown and without other direction, the standard alloy used in your facility should be used.

Lead-Free 1.9 (Differences)

• Lead-free alloys have a higher Liquidous (or melting) temperature than traditional tin-lead solder alloys. Therefore lead-free alloys may require different dwell times and temperatures to create an acceptable solder connection.

• Lead-free alloys may require different fluxes and special cleaning processes.

• Wetting times are generally extended.

Lead-Free 1.9 (Differences)

• Solderability indicators such as wetting angles, joint appearance etc., will generally be different.

• Higher temperatures and longer dwell times may increase oxidation.

• Component lead frames as well as circuit board finishes must be compatible with the solder alloy.

Hand Soldering

• Automated processes (reflow, wave, etc.) do require higher temperature settings

• Hand soldering processes most likely will not need increased temperature settings

Solder Differences

• Lead-free (SAC305)– 217°C Liquidous

• Tin lead (Sn63Pb37)– 183°C Liquidous

• 34°C difference0

50

100

150

200

250

Liquidus

Tip Temperatures

• Typical tip temperature– 315°C (600°F)

• 98°C difference to SAC305

• Typical peak reflow temperature– 245°C to 260°C

0

50

100

150

200

250

300

350

Liquidus

Training 1.6• The quality and reliability of

modified or repaired printed boards and assemblies is highly dependent upon the skill and competence of the person performing these tasks.

• The implementation of proper methods by unqualified personnel can result in a substandard end product. Consequently, achieving successful results with the methods described herein is predicated on the use of properly trained personnel whose skills have been tested and certified to be of a sufficient level of competence.

IPC Training and Certification Program

Goals• Industry developed• Industry approved• Industry traceable

INTERNATIONALLY RECOGNIZED

Industry Acceptance

IPC-7711/7721

Currently Certified IPC Trainers

780

Certified IPC Application Specialists

14,971

U.S. Training Centers 17

International Training Centers

12

Contact information

If you would like more information, contact IPC by email to

answers@ipc.org