For test engineers and managers,automated optical
inspection (AOI) systems have emerged as a
countermeasure to the growing threats of lost
physical or electrical access to assembled PCB. AOI
systems are successfully employed in high volume
PCB applications to complement existing electrical
test methods with noted results of overall better
coverage,and higher yield at later test stages.
Inspection systems are commoditized,readily
available from many suppliers,and primarily
evaluate the presence of assembly defects (solder,
component,assembly),overcoming the need for
physical access that test mandates.

The economic environment in the electronics
industry has changed dramatically over the last two
years. The focus on the production floor has moved
from increasing capacity to improving the yield. One
of the major consequences of this shift in focus has
been increased interest in x-ray inspection.

The slowdown in the electronics industry has allowed the management of electronics products manufacturers to
dedicate time to reconsider their manufacturing strategy. For most of these companies,outsourcing has been in its
interim stages of giving it a try (stage 1) or outsourcing most of its PCB assemblies and/or selling off facilities (stage
2).
Original Equipment Manufacturers (OEMs) should be looking for ways to enter stage 3 of outsourcing - reconsider
the manufacturing strategy,outsource the final assembly (box build) along with PCB assembly and minimize
management costs.
While more and more companies are now looking to further reduce costs and to more quickly introduce new
products to the market,they are also concerned with losing core manufacturing knowledge as well as visibility to,
and control of,the outsourced job.

Shrinking profits and overcapacity have forced Electronics Manufacturers to squeeze every last penny out of Site
Operations. To reduce conversion costs in a short timeframe,some facilities have employed Motorola's
Manufacturing Pulse™ software to promote visibility and real-time control of materials on the shop floor. This
paper will discuss real-world case studies explaining the methodology and tools used to reduce scrap costs by as
much as 46%,while reducing the downtime incurred from material outages. Detailed methodologies include realtime
Statistical Process Control (SPC) on materials attrition,real-time performance alarming to technicians,
historical materials performance reporting,and ERP system integration. In addition,this paper describes how this
single tool covers multiple equipment types such as Fuji CP6,Siemens S20,Siemens F5,Siemens HS50,Universal
GSM2,Universal HSP,Panasonic MPA,and Panasonic MV2.

Manufacturers can use DPMO metrics to reduce the cost of PCB assembly with fewer resources. DPMO data can be
used for predicting the fault spectrum on future products,quoting new business,setting quality targets for
manufacturing,defining test strategies,predicting yields,or estimating shipped quality levels. Manufacturers can
input DPMO and BOM data into cost calculator tools to estimate manufacturing costs. When combined with a few
site-specific assumptions about labor rates and test strategy,roughly 80% of PCB assembly costs fall into place once
there is a clear definition of the DPMO. In this way,manufacturers can determine targets for both in-process quality
and financial profit and loss. Tools are now available to the industry that make use of DPMO data for strategic
decision making applications. Use case examples are shown.

The electronics content of many consumer products has increased substantially over the past decade. Several of the
electronics added to the automobile control vehicle functions that have a direct bearing on the well being and safety
of the passengers being transported. Automotive electronics are also subjected to very harsh environments. For these
reasons,the reliability and quality of electronics components is of utmost concern. Many products are built with a
“no touch-up rule” that prohibits rework if the product does not pass end of line test. For the electronics assembler
this places a heavy burden on a high first pass yield process. The purpose of this paper is to discuss and present
results from a test and inspection strategy adopted by an SMT assembler that includes in-line 3D solder paste and
component inspection to improve first pass yields.

For high reliability applications,the use of x-ray technique has become an additional inspection requirement for
quality control and detection of unique defects due to manufacturing of advanced electronic packages such as ball
grid array (BGAs) and chip scale packages (CSPs). Recently,four x-ray systems were evaluated for their defect
detection capability,especially for damage/cracks induced during thermal cycling of ceramic column grid array
(CCGA)/BGA assemblies. These systems were:
1. Case 1: A 2D real time x-ray with a microfocus source and image intensifier as detector. For this case,position
of detector to x-ray source is a straight line.
2. Case 2: A 2D system with x-ray transmission similar to the case 1 with the exception of detector had off-axis
rotational capability,therefore; providing oblique views at higher magnifications.
3. Case 3: A fully digital tomosynthesis x-ray system that is capable to combine 3D volumetric imaging and
conventional 2D x-ray for a complete inspection.
4. Case 4: A custom made 3D computed tomography (CT) x-ray system. It utilizes a high power microfocus
source (cone and parallel beam) and glass scintillator detector or flat panel digital detector to obtain crosssectional
2D x-ray images with preprogrammed angle views. The reconstruction algorithm then provides a true
3D volumetric display
This paper discusses limitation of each system and provides representative inspection images for CCGA/BGA
assemblies. The assemblies have subjected to various thermal cycle and ranges and have shown different levels of
damage/cracking. The x-ray images were compared to optical images taken by a 3D optical microscopy for outer
rows of array package assemblies.

The advent of miniature surface mount components coupled with increasing lead counts has posed tremendous
challenges during assembly. This is especially true in an Electronics Manufacturing Service (EMS) industry where
the focus has been to increase throughput and first pass yields at lowest cost. Therefore,robust and repeatable
inspection systems need to be employed in order to achieve these objectives. Due to the constraints imposed by the
existing inspection technologies,the effectiveness of automated x-ray inspection system was investigated from a
statistical and assembly perspective. The results were analyzed and significant measures were initiated and
employed to improve the performance of the automated x-ray inspection system and subsequently of the Surface
Mount Technology (SMT) line.

This paper will discuss:
a. Boundary scan as a key test tool that enables the leveraged test approach
b. The advantages of standardizing and reusing design verification tests and PLD programs in the manufacturing
test environment
c. Issues related to the hardware and software infrastructure required to achieve efficient test portability
d. DFT guidelines and other recommendations to improve the linkages between product design,prototype
verification,and high-volume manufacturing tests
e. Case studies demonstrating effective boundary-scan test strategies from design to manufacturing

Boundary-scan has achieved many of the goals envisioned by its original architects and today is in use in thousands
of production facilities around the world to test complex digital printed circuit boards. The original vision of the
IEEE 1149.1 specification,to restore test access and fault coverage to assemblies with few physical test points
relative to the number of electrical nets to be tested,has been attained. Ongoing advances in chip design,system
architecture,and application development tools are extending the power of boundary-scan to support the
implementation of solutions at the system-level as well as the board level.
The rationale for deploying boundary-scan technology within the system hierarchy is described in this paper.
Applications include:
• Providing single-point access to multiple scan chains for testing and in-system programming
• System checkout prior to shipping,including verification of board presence
• Configuring the system for customer-specific requirements
• Testing of system backplane or other interconnection means
• Environmental stress testing
A variety of system-level boundary-scan topologies are available,utilizing the many scan-compatible bridging
devices on the market. This paper will describe the various methods,including multi-drop architecture in which all
boundary-scan signals are routed to all boards within a system environment via a backplane bus,thereby supporting
comprehensive test capabilities. The application of boundary-scan to provide a coherent test capability both at the
board- and system-level will be described. The paper also describes how a carefully considered test strategy,
implemented at design concept,can support a product throughout its complete life cycle.
An example of a successful system level implementation is provided to demonstrate how 1149.1 can be utilized to
solve a wide range of manufacturing problems and for providing comprehensive system level diagnosis.