May 2026 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, has appointed The Murray Percival Company as its manufacturers’ representative for Illinois and Southern Wisconsin.

A third-generation, family-owned business with more than 60 years of experience, The Murray Percival Company is well known throughout the PCB and electronics assembly industry for its technical knowledge and strong customer relationships. The company supports manufacturers with a broad range of assembly equipment, materials, and production solutions, along with a focus on helping customers improve processes and maximize return on investment.

Through this partnership, Murray Percival will represent VJ Electronix’s full line of solutions, including automated rework systems, X-ray inspection platforms, and component counting systems. The goal is simple—provide local support and help manufacturers solve real production challenges with practical, proven technology.

“Bruce Clark and the Murray Percival team bring a deep understanding of the industry and a long track record of supporting customers the right way,” said Don Naugler, General Manager at VJ Electronix. “Their approach aligns well with how we work, and we’re looking forward to building on that in the Midwest.”

Bringing Murray Percival on board gives VJ Electronix a stronger local presence in a region with a solid base of electronics manufacturing, making it easier for customers to access support and expertise when they need it.

VJ Electronix continues to grow its North American rep network to stay closer to customers and respond more quickly.

For more information about VJ Electronix, visit www.vjelectronix.com.
For more information about The Murray Percival Company, visit www.murraypercival.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing 19 Alpha Road, Chelmsford, MA.USA 01824

+1 978 486 4777

www.vjelectronix.com

May 2026 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, has appointed MaRC Technologies, Inc. as its manufacturers’ representative in the Pacific Northwest.

Led by Mike Gunderson, MaRC Technologies supports electronics manufacturers and high-tech companies with equipment, materials, and technical solutions. Headquartered in Oregon, the company has built long-standing relationships across the region and brings a strong understanding of the local customer base.

This appointment builds on VJ Electronix’s existing relationship with the MaRCTex team, following more than a year of successful collaboration supporting customers in Texas. Expanding that partnership into the Pacific Northwest provides continuity for customers while strengthening VJ Electronix’s presence in another key U.S. manufacturing region.

“Mike and his team have already proven to be a strong partner for us,” said Don Naugler, General Manager at VJ Electronix. “They understand the applications, they know the customers, and they’ve done a great job representing our solutions. Expanding into the Pacific Northwest was a natural next step.”

MaRC Technologies will represent VJ Electronix’s full portfolio of solutions, including automated rework systems, X-ray inspection platforms, and component counting systems. The partnership is focused on providing local support and helping customers address real production challenges, from rework of complex assemblies to inventory control and inspection.

“We’ve had the opportunity to work closely with VJ Electronix over the past year, and it’s been a great fit,” said Mike Gunderson, MaRC Technologies. “Their equipment solves real problems on the production floor, and we’re looking forward to bringing that same level of support to customers in the Pacific Northwest.”

VJ Electronix continues to expand its North American representation network to better support customers with local expertise and faster response times.

For more information about VJ Electronix, visit www.vjelectronix.com.

For more information about MaRC Technologies, visit www.marctechnologies.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing 19 Alpha Road, Chelmsford, MA.USA 01824

+1 978 486 4777

www.vjelectronix.com

February 2026 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, has been honored with a 2026 NPI Award in the Repair & Rework Tools category for its Summit LT150 rework system, a next-generation platform designed for large, high-density electronic components.

The LT150 builds on the company’s Summit platform, giving operators a 150 × 150 mm vision area to see the entire component while zooming in on corners for exact alignment. It supports standard board sizes up to 24 × 36 inches, with an optional upgrade for even larger formats, and provides up to 100 mm of top- and bottom-side clearance to safely reach tall connectors, heat sinks, and power modules.

A 4.4 kW top heater paired with up to 11.2 kW of bottom-side heating delivers even thermal performance across large components, keeping solder reflow consistent from center to edge while reducing thermal stress. Balanced heating, dual PID control, programmable airflow, and a 1.5 kW spot heater let operators fine-tune profiles for different materials and package types. The result: faster cycle times, improved throughput, and reliable rework of high-value components.

“The Summit LT150 gives manufacturers the tools to take on assemblies that were previously difficult or risky to rework,” said Don Naugler, General Manager, VJ Electronix. “It’s designed to make large-component rework safer, faster, and more accurate, helping reduce scrap and avoid unnecessary board replacements.”

The NPI Award highlights VJ Electronix’s focus on practical solutions that meet the demands of modern electronics manufacturing.

For more information about VJ Electronix, visit www.vjelectronix.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing 19 Alpha Road, Chelmsford, MA.USA 01824

+1 978 486 4777

www.vjelectronix.com

VJ Electronix Introduces Summit LT150 Rework System for Large, High-Density Assemblies

New platform developed with leading AI OEMs and EMS providers enables reliable rework of components up to 150 mm

March 2026 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, today announced the launch of the Summit LT150, a new addition to its Summit rework platform designed to handle the growing size and complexity of modern electronics assemblies.

The Summit LT150 was developed following extensive roadmap discussions with leading OEMs in the artificial intelligence sector and top electronics manufacturing services (EMS) providers. As AI, power electronics, and high-density systems continue to push the limits of board size and component scale, manufacturers require rework solutions capable of handling larger packages without sacrificing precision or thermal control.

Building on the success of the Summit LT120, the LT150 supports reliable rework of components up to 150 mm. A large 150 × 150 mm vision area allows operators to view the entire component while still zooming into corners for precise alignment and placement.

The system accommodates standard board sizes up to 24 × 36 inches, with an optional upgrade available for even larger formats. Increased clearance—up to 100 mm on both the top and bottom sides—provides safe access around tall connectors, heat sinks, and power modules commonly found in high-power assemblies.

To maintain consistent solder reflow across large component footprints, the LT150 combines a proprietary 4.4 kW top heater with up to 11.2 kW of bottom-side heating. This balanced approach helps maintain uniform temperatures from the center of the component to the edges while minimizing thermal stress on the assembly.

Dual PID control, programmable airflow, and a more powerful 1.5 kW spot heater work in conjunction allowing operators to fine-tune thermal profiles for large challenging AI components. These capabilities help shorten cycle times while maintaining consistent rework quality.

“Manufacturers are dealing with larger components and increasingly complex assemblies, particularly in AI and high-power applications,” said Don Naugler, General Manager of VJ Electronix. “The Summit LT150 was developed directly with input from OEM and EMS partners to ensure it addresses the real challenges they’re seeing on the production floor.”

Interest in the LT150 has been strong following the success of the Summit LT120 platform, as manufacturers look for ways to perform reliable, in-house rework on high-value boards without risking damage or unnecessary replacement.

For more information about VJ Electronix and the Summit LT150 rework system,visit www.vjelectronix.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing 19 Alpha Road, Chelmsford, MA.USA 01824

+1 978 486 4777

www.vjelectronix.com

The new Auto Align feature allows for the alignment of components, including components larger than 100mm, with no operator intervention. The software recognizes the corners of the component and site using fiducials, and then pick locations (centerpoint) are determined automatically.

The Summit 2200i is a high precision, automatic system for small to large SMD assemblies that is capable of handling printed circuit boards up to 22″x 30” and components as small as 01005. The system utilizes efficient convection heating and closed-loop temp control to mimic thoughtfully designed oven profiles.

The system’s easy-to-use 1-2-3-GO graphical user interface and flexible SierraMate rework software minimize operator intervention while maintaining tight process control of all critical parameters and provides product traceability, profile analysis and sharing of profiles between VJE systems.

The independent non-contact site scavenger head safely removes residual solder, eliminates the potential for damage to pads and solder mask, and allows a continuous process without tool change. Operators can complete rework in a single thermal cycle.

For more information about software upgrades, new system purchase or to schedule a demo, visit http://www.vjelectronix.com or  email electronixsales@vjt.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

FOR IMMEDIATE RELEASE

July 2022 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, is pleased to announce that Rocket EMS, Inc. has installed its second XQuik II Plus component counter. When the company acquired its new 50,000 sq ft. facility in Carson City, Nevada, they made the decision to outfit it with the award-winning XQuick II Plus. Rocket EMS now operates an X Quik II at its new Carson City facility as well as its headquarters in the heart of Silicon Valley.

“Working at a fast-paced environment like Rocket EMS is never an easy task to do singlehandedly,” stated Geenno Fontanilla, Director of Engineering at Rocket EMS.

“That is why we rely on partnerships with equipment suppliers like VJ Electronix to provide us with technologically advanced equipment. The XQuick II Plus has been a work horse in our receiving and warehouse departments at both our Nevada and California sites. As we move forward to integrate this into our Voyager 2.0 MES system, our customers would soon have visibility at a component level to ensure accuracy and traceability of their materials on demand.”

The VJ Electronix XQuik II Plus is the solution to today’s demanding component counting requirements. With a cycle time of less than 20 seconds (for both single reel and quad counts), the XQuik II Plus is designed for operational simplicity and automation flexibility. It is easily configured to communicate with any existing MES inventory control system and a sample interface, along with detailed instructions, is provided for the customer’s IT team to quickly customize for their specific needs.

Rocket EMS, founded in Jan 2011, is a Santa Clara, Calif.-based Electronic Manufacturing Services (EMS) company serving fast-growth, high-technology companies. The company is uniquely positioned to meet the very high demands of New Product Introduction (NPI) manufacturing and test. Rocket is a one-stop partner, specializing in ultra-quick-turn (24 – 48 hour) manufacturing of Printed Circuit Boards (PCBs), design and complementary services.

For more information about Rocket EMS, visit www.rocketems.com.

For more information or to schedule a demo, visit www.vjelectronix.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing
19 Alpha Road, Chelmsford, MA.USA 01824
1 978 486 4777

June 2021 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, today announced the appointment of Southwest Systems Technology, Inc. to represent its rework, x-ray inspection, and x-ray component counting systems in the states of Texas, Oklahoma, Arkansas and Louisiana.

“VJ Electronix products are technically solid with great value and performance,” stated Scott Fillebrown, Managing Director at Southwest Systems. “They are exactly what I looked for at my former contract manufacturing company and we are excited to be working with them.”

For more than 33 years, Southwest Systems Technology has been providing sales and service for equipment and materials in both the electronic assembly and semiconductor manufacturing industries. Southwest Systems’ sales engineers are trained in the latest industry processes and technologies.

For more information about Southwest Systems Technology, contact Scott Fillebrown at Scott@SWSystems.com or visit www.swsystems.com.

For more information about VJ Electronix, visit www.vjelectronix.com.

About Southwest Systems Technology, Inc.

Southwest Systems Technology, Inc., was founded in 1989. The company has offices in Dallas, Austin, El Paso, McAllen, and Guadalajara, Mexico. Southwest Systems’ philosophy is to technically present the myriad of products it represents in a thorough and professional manner; proficiently and with discerning sophistication. The company sells products in both the electronic and semiconductor manufacturing industries. It sells capital equipment and materials, and its sales engineers are trained in the latest industry processes and technologies. For more information, visit www.swsystems.com.

About VJ Electronix

VJ Electronix, Inc. manufactures production ready, automated Rework and X-ray inspection systems with many advanced capabilities. The company frequently provides custom solutions tailored to satisfy specific application requirements. VJ Electronix is a worldwide leader in X-ray Inspection and Rework equipment.

Company Contact:

David Hamel, Director of Global Sales and Marketing
19 Alpha Road, Chelmsford, MA.USA 01824

+1 978 486 4777

www.vjelectronix.com

VJ Electronix accepts 25^th industry award in less than 20 years!

February 2022 — VJ Electronix, Inc., the leader in rework technologies and global provider of advanced X-ray inspection and component counting systems, is pleased to announce that it received a 2022 CIRCUITS ASSEMBLY NPI Award in the category of Test and Inspection – AXI for its new APOGEE 90 X-ray inspection system. The award was announced during a special online ceremony on Monday, Feb. 24, 2022. This marks the company’s 25^th industry award as VJ Electronix approaches its 20^th year in business.

The APOGEE 90 microfocus X-ray inspection system is an advanced at-line NDT solution for manual (MXI) or semi-automated Inspection (AXI) of printed circuit boards, components and assemblies. The system is equipped with a 90kV, sealed, microfocus X-ray source that can achieve a spot size as small as 4µm, a 5” HD Digital Flat Panel Detector with 85µm resolution, and 6-axis motorized motion control with oblique angle inspection of up to 45°.

With minimal training, operators can intuitively utilize valuable tools for basic inspection and enhanced analysis of BGAs, QFNs and more. The APOGEE 90 provides reliable inspection for operators to capture the highest clarity 2D & 2.5D X-ray images for defect detection and failure analysis in production environments.

The APOGEE 90 offers optimal performance and operability at a fraction of the cost of comparable X-ray inspection systems. Creatively designed with the superior resolution and automation typically found in higher cost systems, the APOGEE 90 is one of the most powerful and economical X-ray inspection systems to hit the market in 2022.

“The APOGEE 90 is a cost-effective solution that provides the best of both worlds,” Donald Naugler, CTO. “It is very easy to set up automated inspection routines for BGA, PTH and more. For quick manual inspection, the on screen navigation allows the user to click on a picture of the sampl and the manipulator automatically centers the selected object in the live X-ray image.”

Introduced in 2008, the NPI Awards program is an annual celebration of product excellence in electronics surface mount assembly. Premier products based on the finest examples of creative advancement in technology are chosen by a distinguished panel of industry experts.

For more information or to schedule a demo, contact electronixsales@vjt.com.

Abstract—High value devices used in microwave modules and other microelectronic assemblies have become increasingly thin and susceptible to “Component Out Of Pocket” (COOP) conditions that may occur during packaging, shipping, and customer handling. This defect condition is especially problematic for automated assembly which strives to be touch-free and efficient with orderly device presentation.

COOP is a major contributor to “Cost Of Poor Quality” (COPQ) within the business. A funded study into COOP conditions was conducted and multiple root causes were identified.

It was discovered that traditional “waffle packs” have mechanical issues related to looser flatness tolerances with respect to the tray and lid. The addition of a standard clip further contributes to the issue, both of which are key root causes of the costly “Component Out Of Pocket” (COOP) condition.

A novel Lid-Clip System (LCS2) was engineered to compensate for those mechanical issues, bringing robust captivation and preservation of devices in tray pockets. Static dissipative material for lid and clip was selected to provide unparalleled ESD Class 000 protection for high value devices with the lowest voltage susceptibility thresholds.

INTRODUCTION

This paper describes the multiple root causes of the “Component Out Of Pocket” (COOP) (Fig. 1) defect condition in waffle packs that has persisted in the microelectronics industry for decades, complicating the task of achieving zero defects and driving manufacturing costs. Military aerospace and commercial manufacturers alike, worldwide are incurring unnecessary costs in the form of component damage, component scrap, and the non-value added labor associated with “fixing” induced waffle pack defects. Innovation in transportation, handling, preservation, and storage for semiconductor ICs has been lacking.

This is important because semiconductor devices in particular are costly and the additional assembly labor and equipment down time is a cost driver in manufacturing operations that use components with thickness of 0.010-inch and less. These components are particularly susceptible to this defect condition.

II.CHARACTERIZATION / ROOT CAUSES

Multiple causes of COOP defects have been identified (Fig. 2). Many semiconductor industry professionals have failed to recognize the implications of published flatness specifications [1] associated with injection molded trays and lids (i.e., 0.012-inch carbon loaded polypropylene, 0.004-inch carbon loaded polycarbonate) (Fig. 3). For a thin GaAs die, that leaves plenty of egress for escape. Consider the tolerance stack up when selecting from standard lids and trays as it could be as high as 0.024-inch and 0.008-inch for poly-propylene and polycarbonate, respectively. Standard clips also impart deflection of lid and tray material due to the design as shown in (Fig. 4).

For decades, end users and suppliers of components in waffle packs have been pointing fingers, casting blame on one another for migrated components. Keyence VR-3200 3D Scanner [2] was key to visualizing and measuring the flatness tolerances that led to the mechanical issues that cause COOP (Fig. 5). With the advent of an x-ray counter system by VJ Electronix model XQuik II [3] (Fig. 5) developed for BAE Systems

in 2017, specifically designed to count components in sealed waffle packs at the receiving inspection level, we have definitively proven that COOP occurs both at supplier sites and during transit, well before end users have the opportunity to open waffle packs.

Principally, flatness tolerances of the various materials used in the manufacture of waffle pack trays and lids were visualized and measured using equipment shown in (Fig 5). Semiconductor industry component suppliers are typically unaware they are shipping components out of pocket because few employ x-ray systems to validate the effectiveness of their final packaging operation. While there is plenty of blame to be shared for COOP, including by end users, we now have a clearer understanding of the mechanical issues which top the list of multiple root causes.

Figure 6 shows dark orange locations A and C on inside of cover that act as standoffs when contacting top of tray thus allowing components to migrate under the blue locations that measure up to a 0.0094-inch gap.

Another prevalent cause of COOP is the misalignment of loose inserts that leads to pinching of inserts used for the waffle pack assembly process (Fig. 7). One misconceptions is that loose inserts prevent COOP however, our research has shown it can actually contribute to it, as when inserts are misaligned or pinched which is frequently the case. Pinched inserts can be evident along edge in between tray and lid.

The risk of device damage is inherent to components when working with loaded waffle packs with that risk amplified for components ≤0.010-inch thick. The risk of COOP is present when clips are attached and removed, because the lids are essentially unsecured and waffle packs are being tilted to some extent; the lid can pop up on one side when unequal pressure is applied by operator to opposite side of waffle pack. That condition combined with the slightest vibration can cause COOP. It is at this stage of the packing and unpacking process where components are also at significant risk for migration (Fig. 8).

In response to the multiple deficiencies identified in the most commonly used bare die packaging (i.e., waffle pack/chip tray), a novel Lid-Clip System (LCS2) was engineered to pair with these warped pocketed trays to ensure optimal component preservation through the effective gasketing in each and every pocket in order to establish a new industry best practice and defect free transport/handling solution. LCS2 represents an important new option for the mitigation of “COOP”. Our solution is an enhanced lid comprised of low outgassing, static dissipative, low density polyurethane foam and industry-approved interleaf material assembled into a static dissipative injection molded lid using silicone free pressure sensitive adhesive (Fig 9). This is combined with a novel clip design (Fig 9 and Fig 10) which uniformly compresses the lid around its full perimeter, ensuring intimate contact of the entire interleaf against the warped waffle tray surface (Fig 11).

Static dissipative material for the injection molded lid and clip was selected and tested per ANSI/ESD S11.11 to provide ESD Class 000 protection for high value devices with the lowest voltage susceptibility thresholds.

Efficacy of the Lid-Clip System has been demon-strated through rigorous drop testing of 0.002-inch GaN devices from 34 inches using x-ray to verify containment or the absence of COOP condition (Fig. 12). Ten unique novel lids and novel clips were tested and dropped a total of 10 times each for 100 total drops with no detected COOP (Fig. 9). When the standard industry clip was substituted for the new innovative clip, COOP occurred (Fig. 12) demonstrating need for the novel clip.

Overall, this novel Lid-Clip System solves for the costly “Component Out Of Pocket” condition for all sized components but especially for ultra thin components ≤0.010-inch. This system also reduce non-value added Supplier Corrective Action Requests/Return Material Authorizations. The Lid-Clip System has tremendous potential to curb millions of dollars in waste and improve component process efficiencies worldwide.

REFERENCES

[1] Entegris website Tray Wizard (entegris.com)

[2] Keyence website Models: Wide-Area 3D Measurement System | KEYENCE America Ryan Mathes

[3] X-Ray – VJ Electronix, Robert Kerwin

[4] Forgione Engineering, Matteo Forgione

Abstract

Surface Mount Rework systems have evolved into sophisticated thermal processing tools with the ability to accurately mimic original reflow oven profiles at a localized rework site. Features such as automated profile generation allow the user to quickly define workable profiles for a wide variety of applications. However, many of today’s applications demand more carefully crafted profiles than can be achieved using traditional methods.

Sensitive components such as optical devices, connectors, and certain package types, to name a few, have specific requirements and limitations that go far beyond the typical solder joint time-temperature profile. Elevated temperatures of lead free processes further amplify thermal management issues.

Rules Based Thermal Profiling allows automated profile generation with a combination of parameters that that are set to meet each situation. Multiple criteria may be specified and prioritized to yield the most reliable process for reworking sensitive components and assemblies.

Introduction

When reworking printed circuit board assemblies (PCBA) the process engineer must develop thermal processes that assure reliable solder joints while protecting delicate components and boards. Ideally, the profile will closely replicate the profile used in the initial assembly process in order to provide the greatest confidence that the assembly will have the same or similar performance and reliability as the original product.

The thermal profile is created to subject the solder joints to a temperature excursion that will cause the fluxing, melting, wetting and cool down operations to occur in a correct fashion. It is generally agreed that, for a given flux/solder combination, this thermal profile should always be the same regardless of the physical make-up of the assembly. However, it is evident that massive assemblies will require a great deal more energy to achieve this “golden” profile than will assemblies of small thermal mass. The secret lies in the ability to generate a thermal cycle that will transfer just the correct amount of heat to the assembly to achieve the desired result.

The thermal management needed to do this has to take into consideration not only the requirements of the solder joints but also the constraints imposed on the process by the presence of the sensitive components that have strict temperature limitations. Once these limitations are known, Rules Based Thermal Profiling can be employed to establish boundaries and to insure they are respected while, at the same time, observing all the requirements for good soldering.

Thermal Process for Rework

Generating thermal profiles for rework is more difficult than generating profiles for reflow in an oven. When an assembly is passed through a reflow oven, the entire mass is heated, resulting in a relatively uniform temperature throughout. Belt speeds and zone temperatures may be adjusted so that the desired thermal profile is achieved.

In the case of rework, heating is localized, for the most part, to the rework site. As a result, profiling is more difficult since thermal characteristics of each component and assembly can vary considerably, one from another.

Heating for rework is accomplished through a combination of bottom side (board heating, or conditioning) and top side (component heating). As the component is heated, thermal energy is dissipated through the board due to its heat sinking effect which is a function of its thermal mass. The mass of the component and the rate of dissipation will affect the required energy and hence the heating parameters.

Bottom heating is used to bring the entire board to an intermediate temperature. This is done to minimize stress caused by local heating, and to reduce the extraction of heat from the rework site. However, since the entire board can not be heated to reflow temperatures there will be lateral temperature gradient, and hence transfer of thermal energy (heat) from the rework site to the surrounding areas.

In a convection rework system most of the heating for area array devices (BGA, CSP, Flip Chip, etc.) is accomplished via transfer of energy from the hot gas to the top side of the component. Heat then flows through the body of the component to the component-solder interface, through the solder, through the board-solder interface, and into the board (see Figure 1). Copper conductors within the board, especially large power and ground planes, provide a substantial thermal path to draw heat away from the rework site.

To corroborate this “through the component” heat flow, an experiment was performed to determine the extent of heat transfer due to hot gas flowing under a BGA component. A test board was constructed with a 27mm PBGA mounted on a sample FR4 board. The board was drilled from the back side and a thermocouple was inserted, contacting one solder ball, and secured with thermally conductive epoxy(1).

Two thermal cycles were executed with identical heater parameters (see Figure 2). The rework nozzle was positioned on the board, gasketing to the board surface, and deflecting exhaust air upwards and away from adjacent components. The first set of data was taken using the standard rework process (Cycle 1). Prior to the second cycle (Cycle 2) a thin layer of Kapton tape was placed along the component edges, sealing the gap between the BGA body and the board to prevent possible flow of hot gas under the component body.

The test showed that taping the gap between the BGA body and the board had no significant impact on the temperature measured at the solder joint, confirming the fact that the majority of heat transfer occurs via conduction through the component body rather than from lateral hot gas flow under the component.

Impact of Materials on Heating

The flow of energy through the component can be damaging if not properly managed. Certain components, depending on packaging materials used and construction, can be especially susceptible to thermal damage due to their low thermal conductivity.

Table 1 provides examples of thermal conductivity for typical materials used in electronic assembly. Ceramic packages conduct heat far better than plastic packages. Polyimide and epoxy based substrates have low thermal conductivities. Thermally enhanced packages, especially those with thermal via connections will conduct heat quite rapidly (but not necessarily uniformly across the package).

Table 1 – Approximate Thermal Conductivity of Various Materials 2,3,4,5

In many cases temperature ramp rates that are acceptable in a reflow oven may not be acceptable in a rework process because of the temperature gradient that occurs between the top of the package (closest to heat source) and the bottom of the package (farthest from the heat source). The process engineer, in considering the choice of ramp rate, should be aware of this interaction between process parameters and needs the ability to take suitable precautions.

Figures 3, 4 and 5 show peak temperatures from rework reflow profiles generated for three package types. The profiles were created with the main requirement being to provide a peak temperature between 210 and 215º C at the solder joint. The figures illustrate the relative differences in temperature between the top heater, the top of the package, and the solder joint. The plastic BGA package exhibits a the highest package top temperature due to its low thermal conductivity. The ceramic BGA exhibits little temperature difference due to its high thermal conductivity. (Peak temperatures are summarized in Table 2.)

Table 2 – Peak Profile Temperatures

PBGA CSP CBGA Top Heater 355 276 264 Package Surface 267 246 217 Solder Joint 214 214 213

Process engineers must avoid exceeding maximum package temperatures in low thermal conductivity packages such as large, plastic encapsulated BGAs. Profiles with moderate ramp rates measured at the solder joint may result in damaging high temperatures at the top of the package. On the other hand, packages with high thermal conductivity may ramp extremely quickly. Overly aggressive profiles may exceed ramp specifications causing thermal stress damage.

Protecting the Component

Rules Based Profiling allows the process engineer to define additional parameters, beyond the typical time – temperature – ramp rate, to protect delicate components when defining a new rework process. New parameters include maximum component temperature (usually measured at the top of the package), maximum top heater temperature, maximum ramp rates, and minimum/maximum times for flux activation and time over liquidus, all of which can be consistent with the desired soldering process parameters.

Protection of a thermally sensitive package with low thermal conductivity can be achieved by monitoring and limiting the temperature at the top of the package. By setting Figure 6 – Advanced Auto Profile Rules Screen a rule to limit the package temperature, the normal profile parameters are automatically modified to meet the constraints set by the rule (see figure 6).

A profile was generated for the plastic BGA package (original profile shown in Figure 3) with a rule limiting the package top temperature to 250°C. A thermocouple was attached to the top surface using thermally conductive epoxy1. Careful attention was paid to avoid creating excessive surface area on the epoxy bead attaching the thermocouple. Typical parameters were used as a starting point for profile definition(6). The additional package top temperature rule was imposed.

The Auto Profile software functioned as normal until the temperature measured at the top of the package reached the specified limit. Once the limit was reached the top heater control switched over to Rule Based Control (see Figure 7). The ramp rate was automatically adjusted to maintain the temperature within the limits. Reflow dwell time was dynamically corrected to keep time above liquidus within the specified range (Reflow Time Range). The resultant package temperature exceeded the limit by two degrees, but remained 15 degrees lower than the profile that was generated without application of the rule.

Having the ability to monitor the temperature at the top of the package and automatically provide correction during the “Learn” phase of profile generation is a powerful tool in the task of protecting delicate components. If the two degree overshoot allowed by the algorithm exceeds acceptable profiling goals, an offset can be included in the rule (i.e., setting the limit to 248°C) to satisfy this requirement.

Many types of components may benefit from this approach (see Figures 8a, 8b and 8c). For instance, a popular Flip Chip BGA construction leaves the bare IC exposed directly to hot gas. The bodies of leaded surface mount connectors often have strict temperature limits (typically 160° C). The optical elements within fiber optic transducers and receivers quite often must be held well below reflow temperatures. In all of these cases the sensitive areas of the component may be instrumented, and rules set to maintain the profile within prescribed limits.

Figure 8a – Flip Chip CBGA	Figure 8b – SMT Connector	Figure 8c – Optical Transducer

Alternative Approach

There are often circumstances when the attachment of a thermocouple to the top of the package is not convenient or perhaps not possible. For instance, it is not practical to permanently attach a thermocouple when a limited number of boards are to be reworked. In these cases a simple alternative rule may be applied.

Rather than having to measure the actual temperature at the top of the component, previously established data can be used to define the temperature relationship between the top heater and the top of the package. This relationship is based primarily on the materials and construction of the component.

A review of data from the prior rule based profile (Figure 7) shows that for the PBGA construction in question, a maximum package temperature of 250°C can be maintained by limiting the top heater to no greater than 70°C above the solder joint temperature during the reflow portion of the rework profile.

The new rule to limit the temperature difference between the top heater and the solder joint was specified. The thermocouple on the top of the package was left in place for data collection only – the feedback was not used to set the profile. The Auto Profile “Learn” sequence was again executed.

As the profile approached peak reflow temperature the top heater control maintained the specified solder joint ramp rates and temperatures. Several seconds after the solder joint passed liquidus, the temperature difference between the top heater and solder joint reached the maximum. At this point the top heater switched to Rule Based Control. The ramp rate was automatically modified. The reflow dwell time was dynamically adjusted to keep the profile within specified minimum and maximum time over liquidus.

The resultant profile is shown in Figure 9. The peak package top temperature was 253°C, nearly the same results as those achieved with control using feedback from the package top. Again, the desired protection of the component was achieved. However, obtaining consistent results requires knowledge of the package materials and construction, and experience with similar package types in order to determine the proper limits to apply.

Conclusion

Over the past five years great strides have been made in the development of software packages to assist in the generation of a thermal profile without having to resort to traditional trial and error methods. However, the profile has invariably been based on the need to subject the solder joints on a component to a given set of thermal process conditions. It has often not been possible to take into account the harmful effects that can be encountered by, for example, other parts of the same component that are particularly temperature sensitive.

This paper has highlighted the need to be able to control heat sources in such a way that the desired soldering requirements can be attained while, at the same time, avoiding damage to sensitive components. It has been shown that Rules Based Thermal Profiling goes a long way to achieving these objectives and, as a consequence, seemingly incompatible constraints can often be overcome.

Though not every set of constraints can be met by imposing rules – i.e., one can not ignore the laws of physics – many conditions can. Strategies for applying rules, and algorithms employed within the control software, will continue to evolve to meet new and more difficult requirements.

Rules Based Thermal Profiling offers the Process Engineer the ability to more easily tailor rework processes to satisfy today’s increasingly stringent needs and still maintain the yields and reliability that are paramount in the current market environment.

Acknowledgements: The authors would like to thank Bryan Pinette and Jeff Samuelson for their ingenuity and extensive effort in development of the software platform that enabled Advanced Auto Profile and Rules Based Profiles. We would also like to thank Ernie LaFleur for his insight into process requirements and system controls that proved invaluable in development of the algorithms on which the rules are based.

References:

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