IPC-CM-770: Complete Guide to PCB Component Mounting Guidelines

When you’re setting up a new assembly line or troubleshooting placement issues, having solid guidelines for component mounting makes all the difference. IPC-CM-770 is the industry’s go-to resource for exactly that—a comprehensive document covering everything from basic through-hole insertion to advanced flip chip attachment.

Unlike acceptance standards that tell you what’s good or bad after the fact, IPC-CM-770 focuses on the “how” of component mounting. It provides practical guidance for preparing and attaching components to printed circuit boards, addressing design considerations, machine capabilities, and process interactions that affect assembly success.

What Is IPC-CM-770?

IPC-CM-770, officially titled “Component Mounting Guidelines for Printed Boards,” provides effective guidelines for the preparation and attachment of components during PCB assembly. The document reviews pertinent design criteria, discusses impacts and issues related to different mounting technologies, and covers techniques for both manual and automated assembly processes.

The current revision, IPC-CM-770E, spans 150 pages and addresses modern assembly technologies including surface mount, BGA, and flip chip alongside traditional through-hole methods. It also considers downstream processes—soldering, cleaning, and coating—that component mounting decisions directly affect.

What sets IPC-CM-770 apart from other assembly documents is its scope. Rather than focusing narrowly on one technology or process step, it takes a holistic view of component mounting from design through attachment.

IPC-CM-770 Document History and Evolution

IPC-CM-770 has been around since 1968, evolving alongside component and assembly technology. Understanding this history helps explain why certain sections exist and how the document has adapted to industry changes.

The jump from Revision D to E was significant. By 2004, BGA packages had become mainstream, flip chip was gaining traction, and assembly processes had become considerably more complex. Revision E addressed these technologies while maintaining backward compatibility with traditional through-hole guidance that many assemblers still needed.

Complete Section Coverage in IPC-CM-770

IPC-CM-770 organizes its content logically, starting with general concepts and progressing through specific mounting technologies. Here’s what each major section delivers.

General Guidelines

The opening section establishes foundational concepts that apply across all mounting technologies. Design options and considerations receive significant attention because mounting decisions made during design directly impact assembly feasibility and yield.

Key topics include material compatibility, handling and storage requirements, ESD protection protocols, and material movement systems. The ESD guidance references EOS/ESD Association standards and covers wrist straps, worksurfaces, and flooring requirements—critical for protecting sensitive components during assembly.

Component Guidelines in IPC-CM-770

Before mounting components, you need to understand their characteristics. IPC-CM-770 covers component characterization and classification, packaging and delivery systems, and lead/termination finishes that affect solderability and reliability.

The moisture sensitivity coverage is particularly valuable. IPC-CM-770 explains how moisture-sensitive devices must be handled, stored, and processed to prevent “popcorning” during reflow—a failure mode that can destroy components and assemblies.

Printed Board Structures and Thermal Management

Component mounting doesn’t happen in isolation—the board structure matters. IPC-CM-770 addresses supporting-plane structures, constraining cores for CTE management, and thermal considerations that affect component reliability.

Heat sinks, spacers, component-lead spreaders, and thermally conductive insulators all receive coverage. For high-power applications, the guidance on thermal interface materials and heat sink mounting helps engineers make informed decisions about thermal management approaches.

Through-Hole Component Mounting

Despite the dominance of surface mount, through-hole technology remains essential for connectors, high-power components, and mechanical attachment points. IPC-CM-770 provides comprehensive coverage of through-hole mounting techniques.

Axial and Radial Leaded Components

The handbook covers lead forming, insertion methods, and clinching techniques for both axial-leaded (resistors, diodes, some capacitors) and radial-leaded (electrolytic capacitors, transistors) components.

Lead forming guidance addresses bend radius requirements, stress relief considerations, and the relationship between lead forming and solderability. The document explains how improper forming damages lead finishes and creates stress concentrations that can cause field failures.

DIP, PGA, and Connector Mounting

Dual in-line packages (DIPs), pin grid arrays (PGAs), and through-hole connectors each have specific mounting considerations. IPC-CM-770 covers insertion force requirements, lead-to-hole relationships, and mechanical securing methods.

For connectors, the handbook addresses press-fit versus soldered terminations, keying and polarization, and the mounting forces that boards must withstand. This guidance helps designers specify appropriate board thickness and copper weight for connector applications.

Lead Termination Methods

IPC-CM-770 documents various lead termination approaches including clinched leads (partially and fully clinched), straight-through leads, and offset bent leads. Each method has implications for wave soldering access, component retention during handling, and rework feasibility.

Surface Mount Assembly Guidelines in IPC-CM-770

Surface mount technology coverage in IPC-CM-770 spans from basic chip components to complex area array packages. The guidance addresses both design and process considerations.

Chip Components and Passive Devices

For chip resistors, capacitors, and inductors, IPC-CM-770 covers land pattern requirements, component orientation for wave soldering (if applicable), and placement accuracy requirements. The document explains how component size affects placement machine capability and inspection requirements.

Tombstoning—where chip components stand up on one end during reflow—receives attention as a common defect mode. IPC-CM-770 discusses design and process factors that contribute to tombstoning and provides guidance for prevention.

Leaded SMT Packages (SOT, SOIC, QFP)

Small outline transistors (SOT), small outline integrated circuits (SOIC), and quad flat packs (QFP) represent the workhorses of leaded surface mount. IPC-CM-770 covers lead coplanarity requirements, land pattern design, and the relationship between lead pitch and process capability.

Fine pitch devices (lead pitch below 0.5mm) require special attention. The handbook discusses placement accuracy requirements, solder paste printing considerations, and inspection methods appropriate for fine-pitch assemblies.

BGA Component Mounting Guidelines

Ball grid array packages transformed high-density assembly but introduced new mounting challenges. IPC-CM-770 addresses BGA-specific considerations including ball coplanarity, land pattern design, and X-ray inspection requirements for hidden solder joints.

The document also addresses BGA variants including chip-scale packages (CSP) and micro-BGAs with finer pitch requirements.

Read more IPC Standards:

MIL-PRF-38534: Hybrid Microcircuits Military Specification Guide for Engineers

MIL-PRF-31032: The Definitive Guide to Military-Grade PCB Requirements

MIL-PRF-19500: Military Semiconductor Device Specification Explained

MIL-PRF-123: High-Reliability Ceramic Capacitor Military Standard

MIL-I-46058CMIL-I-46058C: Military Conformal Coating Specification Complete Guide

MIL-HDBK-263: ESD Control Handbook & Implementation Guide

J-STD-075 Guide: PSL Classification for Passive Components & Assembly Process Limits

J-STD-035 Guide: Acoustic Microscopy for IC Package Inspection & Defect Detection

J-STD-033 Guide: MSD Handling, Floor Life, Baking & Dry Storage Requirements

J-STD-032 Explained: Ball Grid Array Ball Construction & Performance Specs

J-STD-027 Guide: Mechanical Outline Standard for Flip Chip & CSP Packages

J-STD-020 Guide: MSL Classification, Reflow Profiles & Moisture Sensitivity Testing

IPC/WHMA-A-620 Explained: Complete Guide to Cable & Wire Harness Standards

IPC-SG-141: Complete Guide to S-Glass Fabric Specifications for PCB Laminates

IPC-QF-143: Complete Guide to Quartz Fabric Specifications for RF/Microwave PCB Laminates

Flip Chip and Advanced Packaging in IPC-CM-770

Flip chip technology—mounting unpackaged semiconductor die directly to substrates—represents the high-end of component mounting complexity. IPC-CM-770 dedicates substantial coverage to flip chip assembly.

Flip Chip Interconnect Types

The handbook covers various flip chip bump technologies including solder bumps, gold bumps, and conductive adhesive approaches. Each technology has different processing requirements, and IPC-CM-770 explains the tradeoffs.

Underfill—the epoxy material applied between flip chip die and substrates—receives detailed coverage. The document explains why underfill is necessary (CTE mismatch stress relief), application methods (capillary flow, no-flow), and curing requirements.

Wire Bonding and Chip-on-Board

Chip-on-board (COB) assembly using wire bonding provides an alternative to flip chip for die-level attachment. IPC-CM-770 covers ball bonding and wedge bonding techniques, wire materials (gold, aluminum, copper), and encapsulation methods that protect wire bonds.

TAB (tape automated bonding) also receives coverage, though this technology has become less common as flip chip and wire bonding have improved.

Design for Assembly Considerations

Throughout IPC-CM-770, design for assembly (DFA) principles appear. The document helps designers understand how their decisions affect assembly feasibility and yield.

Component Orientation and Spacing

Proper component orientation affects wave soldering results, facilitates inspection, and simplifies rework. IPC-CM-770 provides guidance on orienting similar components consistently, maintaining adequate spacing for inspection access, and avoiding shadowing during wave soldering.

Fiducial Requirements

Machine vision systems require fiducial marks for alignment. IPC-CM-770 covers global and local fiducial placement, size and shape requirements, and clearance zones that must remain free of solder mask and silkscreen.

Component Standoff for Cleaning

If assemblies require cleaning after soldering, component standoff heights matter. IPC-CM-770 documents minimum standoff requirements that allow cleaning solutions to flow beneath components and remove flux residues effectively.

IPC-CM-770 vs. Related IPC Standards

Understanding how IPC-CM-770 relates to other IPC documents helps you select the right references for specific needs.

The most common confusion is between IPC-CM-770 and IPC-A-610. Simply put, IPC-CM-770 tells you how to mount components correctly; IPC-A-610 tells you whether the result is acceptable. Both documents are necessary for a complete assembly quality system.

Who Needs IPC-CM-770?

IPC-CM-770 serves multiple roles across the electronics manufacturing ecosystem.

For contract manufacturers handling diverse products, IPC-CM-770 provides a common reference that applies across customer requirements. For OEMs, it helps communicate assembly expectations to manufacturing partners.

Where to Get IPC-CM-770

IPC-CM-770 is available through several authorized channels. Always purchase official copies for accuracy and to support continued standards development.

IPC membership provides significant discounts if your organization purchases multiple standards. The member price for IPC-CM-770 is approximately 35% below the non-member price.

Frequently Asked Questions About IPC-CM-770

What does “CM” stand for in IPC-CM-770?

“CM” stands for “Component Mounting.” IPC uses letter prefixes to categorize document types—CM indicates guidelines specifically focused on mounting components to printed boards. Other prefixes include A (Acceptability), D (Design), and T (Terms/Testing).

Is IPC-CM-770 a mandatory standard or a guideline?

IPC-CM-770 is a guidelines document, not a mandatory specification. It provides recommendations and best practices rather than requirements. However, contracts or quality systems may invoke IPC-CM-770 by reference, making its guidance contractually binding in those contexts.

How does IPC-CM-770 relate to IPC-A-610?

IPC-CM-770 provides guidance for achieving good assembly results; IPC-A-610 provides acceptance criteria for evaluating those results. Use IPC-CM-770 during process development and setup; use IPC-A-610 during inspection and acceptance. Both documents complement each other in a complete quality system.

Does IPC-CM-770 cover lead-free assembly?

IPC-CM-770E was published in 2004, during the transition to lead-free assembly. While it addresses component finishes and process considerations relevant to lead-free, specific lead-free soldering guidance is better found in J-STD-001 and related documents. The fundamental mounting guidelines in IPC-CM-770 apply regardless of solder alloy.

When will IPC-CM-770 be updated?

IPC has not announced a specific revision timeline for IPC-CM-770. The current Revision E remains adequate for most assembly technologies, though advanced packaging developments (2.5D/3D integration, embedded components) may eventually require updates. IPC encourages users to participate in standards development committees if they identify needed updates.

Getting Maximum Value from IPC-CM-770

IPC-CM-770 works best as a reference during design reviews and process development rather than a document you read cover to cover. When evaluating a new component type or assembly technology, locate the relevant sections and apply the guidance to your specific situation.

For new engineers, reading the general guidelines and component characterization sections provides valuable background that applies across all assembly work. More experienced engineers typically jump directly to technology-specific sections as questions arise.

Cross-referencing IPC-CM-770 with related documents (IPC-A-610, J-STD-001, IPC-7351) creates a comprehensive assembly knowledge base that addresses design, process, and quality requirements from multiple perspectives.

Final Thoughts on IPC-CM-770

Component mounting is where assembly quality begins. Design decisions, component selection, and process setup all influence whether assemblies meet their reliability requirements. IPC-CM-770 provides the guidance needed to make informed decisions across all these areas.

Whether you’re mounting basic chip resistors or advanced flip chip packages, IPC-CM-770 offers relevant guidance grounded in decades of industry experience. The 150-page document represents collective knowledge from component manufacturers, assembly equipment suppliers, and electronics manufacturers working together through IPC’s standards development process.

For assembly operations seeking to improve first-pass yield, reduce rework, and build reliable products, IPC-CM-770 provides a solid foundation of component mounting best practices that apply across industries and applications.