Paperless Laboratory: Increased Efficiency and Traceability in Microelectronics Assembly Authors: James O’Brien, Julie Adams, Richard Hueners Choosing an assembly company for precision wire and die attach packaging depends on more than just machines and personnel to get the job done right. It takes an organization capable of best-in-class production methods that can be trusted with valuable materials, IP and product integrity and can prepare a product for successful volume manufacturing. Palomar Technologies Assembly Services (“Assembly Services”), located in Carlsbad, CA, features an advanced, automated microelectronic assembly environment run by a team of experienced managers, engineers, technicians and operators. Within its secure facility, this lean and nimble operation focuses on high value-add assembly. By working with the most advanced technology, capabilities are pushed and new methods of effective assembly production are developed. As innovations are required to meet rigorous microelectronic assembly requirements while achieving the highest level of productivity and accountability, Assembly Services engineers have developed an automated paperless manufacturing environment and integrated it directly with an automated assembly infrastructure—and called it ADMA.

WHAT IS ADMA? Automated Data Management and Analysis (ADMA) is a unified system that improves all aspects of process development and assembly life cycle, reducing costs through increased yield and improved resource utilization. By removing the paper factor1 from the lab data collection, mapping process, and implementing automated computer controlled traceability, ADMA ensures the clean rooms at Palomar Technologies work more efficiently than ever.

                                                                                                                         1  The paper factor increases the probability of human error, increases lab contaminates , decreases productivity up to 95%versus paperless system – Rich Hueners  

Figure 1: ADMA Main Window

ADMA automatically collects data exported from the automated assembly equipment’s core software and sends it to an analysis application. ADMA then creates graphical and numerical analyses of the performance data, which can be output for monitoring and further analysis, e.g., with SPC software and component traceability. All data is categorized and stored in time-stamped directories, down to the (ms) for sufficient granularity (see Figure 1), allowing for both time- and event-based trending of key variables to maintain a clear picture of process status. Process and equipment performance data can be viewed across multiple applications, multiple locations, multiple machines and multiple platforms of Palomar Technologies equipment. LABORATORY TOOLS AND PROCESSES ADMA is one of many tools used by Assembly Services. Assembly Services utilizes Palomar Technologies’ world-class automated high-accuracy wire and die attach equipment, along with alliance products including automated fluid dispensing systems, manual and semi-automatic bonders, wire pull testers, die sorters and wafer punch up systems. Assembly Services features a highly combination of decades of process experience in eutectic die attach, wafer bumping and fluid dispense with such superior packaging equipment as:

This  screen  shows  some  of  the  categories  of  data  managed  by  ADMA;  each  category  may  include  time  stamped  items  underneath  it.  

• Ultra-high precision 6500 Die Bonder, which can perform VCSEL placement applications and precision eutectic wafer scale packaging2

• Hi-Rel 8000 Wire Bonder/Ball (Stud) Bumper, suitable for odd form factor parts, complex wire shapes with stand-off stitch, security bumps and chain bonding3 over a 6” x 12” work space

• Ultra-flexible 3800 Die Bonder, designed for fully automatic, precision assembly • GPD Global Max Series precision fluid dispensing system, capable of fine dot and line control and

encapsulation. • Royce Instruments 650 Universal Bond Tester and DE35-ST Semi-Automatic Die Sorter RELIABLE PROCESS CONTROL Prior to this paperless laboratory, Assembly Services used a paper traceability system, with spiral notebooks, pencils and people. While this was sufficient for a time, an automated “reliable process control” system with stringent traceability features at its core, was necessary. Reliable process control is assured with ADMA through the continuous verification of operational data against process documentation and control limits. This also enables multiple equipment sets and applications to be interleaved for better time and resource utilization without a sacrifice of quality. Convenient access to data and process documentation, at each work station, allows operators to reference previous build processes and automatically track materials throughout the assembly to ensure process continuity (see Figure 2).

Figure 2: Material Inventory in ADMA

                                                                                                                         2  see “Micron Level Placement Accuracy for Wafer Scale Packaging of P-Side Down Lasers Optoelectronic Components” - ECTC Conference, May 26, 2009, by Dan Evans and Zeger Bok, Palomar Technologies  3  see “Odd Form Factor Package Wire Bond Case Studies” - IMAPS Wirebond Workshop, July 13, 2009, by Dan Evans, Palomar Technologies  

CONTRACT ASSEMBLY Contract assembly is all about production, uptime and yield. When ADMA was conceived, its engineers deemed that it was not wise to put production equipment on the corporate network. In response, engineers created BonderNet with a dedicated server, referred to as “Rome Server”, thus applying the phrase “all roads lead to Rome.” This architecture ensures a more controlled and secured IT environment for the specialized equipment. All process data and instructions can be equally accessed from any of the computers in the lab. The inherent redundancy of the access point architecture means if one goes down, production will continue uninterrupted, as shown in Diagram 1. The Rome Server ensures that all access point PCs and all machine configuration data are backed up and available for immediate recovery.

Diagram 1: Rome Server

VALUE-ADD VIA THROUGHPUT AND YIELD Value-add is defined as revenue minus non-labor costs of input. High value-add is the enhancement added to the product before reaching the customer, or simply a high measure of output (value) added to the device before it gets back into the customer’s hands. At Assembly Services, core is “high value-add” and ADMA enhances the value-add of any product it is used to manage without added cost. Productivity, yield and throughput are improved by monitoring and correlating build process data with machine recipes, calibration and performance data. Understanding the key process variables and maintaining proactive process control are all facilitated by ADMA, enabling increased profitability and customer satisfaction.

Streamlining operations is achieved by documenting and archiving all transactions for laboratory processes including monitoring overhead, timecards and logging due-diligence activities such as daily laboratory ESD testing and particle counting. At times, class 1000 clean rooms are required for highly sensitive packaging processes. Having clear laboratory work rules and disciplined record keeping via ADMA ensures that valuable materials are not contaminated or misplaced. Staff, tools and equipment are held strictly accountable to operational requirements, keeping costs down, maximizing efficiency and improving quality. Case Study #1 – PAPERLESS TRACEABILITY REQUIRED Defense, optoelectronic and medical device manufacturers consider traceability to be essential. For this reason, we will look at a U.S. optoelectronic device manufacturer startup company. This company came to Assembly Services with an active optical cable application formatted for 6” wafer scale packaging. The company required microelectronic process development and production, but was not ready to commit to purchasing the required range of capital equipment. Because their need was ultra-high accuracy die attach, Assembly Services dedicated a 6500 Die Bonder retrofitted for wafer scale packaging and designed a pulsed heat tool for the eutectic die attach. A 3500 Die Bonder, and later a 3800 Die Bonder4, was brought in to do multiple epoxy die attach. A GPD-Global dispenser completed the encapsulation and other automated fluid dispensing in large lots. At any given point in time, up to four machines were working under the eye of one technician and overseen by one engineer. Once the equipment program was written and the work flows were set up, the technician or operator simply needed to press “go.” This customer absolutely required a contract manufacturer that could provide 100% part traceability and inspection. This was a stringent requirement to maintain tight process control of the 3000+ assemblies per wafer undergoing multiple assembly steps. Due to the immense amount of data from one wafer, let alone hundreds, ADMA became a key element to ensuring this customer’s success providing:

• Efficient processing of the wafer—both assembly and inspection used wafer mapping for the 6500,3500 and 3800 Die Bonders

• Inspection data was compiled into a custom Certificate of Conformance (see Figure 3) • Costly mistakes were avoided using clearly documented instructions (see Figure 4) • Within a few repeat orders, Assembly Services quickly built a viable inventory and enabled the

customer to ship known-good product to market faster Without a paperless traceability system, Assembly Services could not have supported this particular customer. The post-measuring requirements were significant. The wafers were large and had thousands of sites. The assembly process was complex, using multiple steps and multiple machines. Software automation significantly reduced risks of fundamental human errors. The customer gained business by meeting their customers’ expectations by providing good product in a timely manner.

                                                                                                                         4  3800  Bonder  was  brought  to  market  in  mid-­‐2010;  as  this  customer’s  first  builds  pre-­‐dated  2010,  earlier  die  attach  processes  for  this  customer  were  done  on  a  3500.  In  2011,  Assembly  Services  managers  deemed  this  customer  would  benefit  from  the  latest  die  attach  technology.  The  3800  then  replaced  the  3500  -­‐  all  previously  written  programs  ported  over  to  the  3800  for  a  seamless  transition.    

Figure 3: Example of a Custom Certificate of Conformance

Figure 4: Build Process Tracking

Case Study #2 – THE DORMANT CUSTOMER A global MEMS and HB LED device manufacturer became an Assembly Services customer in late 2008. With their six-month HB LED forecast build, they were prime candidates for ADMA. A new work flow was set up by the floor manager: shipping of parts à work order flow tag (WOFT) à traceability data for build à duration of build (a sample screen shot is shown in Figures 5a and 5b). The product was already prototyped but still required three weeks of process development to tailor it to small-scale production. Once process development was completed, the production began. A six-month forecast and purchase agreement was made. At the end of this term, the company’s management decided to shift focus elsewhere. Assembly Services wrapped up the job and archived all the build data. Two years later, the customer came back with the request to re-start production. In a paper-reliant (non-ADMA) environment, restarting production would be labor intensive and costly, but possible. The product would likely have to be redeveloped. Any learning that took place two years prior would be incomplete, which equates to re-work. Attempting to validate information which may not have been well organized or thoroughly documented, locating documents, processes, programs and instructions would be time consuming, further pushing out lead times and time-to-market. In short, the wheel of the project would have to be reinvented to meet the same good results achieved the first time around. But, this was not the case; the customer was up and running almost immediately. Assembly Services, as a direct result of ADMA, had this two-year dormant customer in production within days rather than weeks. Because of the ADMA tool and Assembly Services’ thorough quality control methods, the customer was the beneficiary of: • No redevelopment costs. Savings = $30K to $50K • No process related re-work costs. Savings = $15K or more • Actual time-saving(s) per task. Concise, detailed work instructions with package parameters,

process flow, part specific programs, tool and time utilization data were available immediately. Savings = 15 production days

• Total Savings: $45,000 - $65,000 + 3 (5) day production weeks

Figure 5a: Example of WOFT (Collapsed Detail Step)

Figure 5b: Example of Detailed Step in the WOFT

 

Case Study #3: THE ESTABLISHED DEFENSE CONTRACTOR Palomar Technologies is formerly a division of Hughes Aircraft and has a combined 35 years of OEM experience. Palomar Technologies customers are some of the largest military, medical and optoelectronic companies in the world. These are well-heeled businesses, built on device excellence. To go outside of their own facility for micro-optoelectronic assembly is out of the norm. Nonetheless, when asked why a defense contractor chose Assembly Services to assemble their newest high-value-add optoelectronic device, they answered “because they’re the experts.” This project was too small and too specialized for their current engineering and production environment. Yet, it was important enough to make an investment, develop a prototype and begin limited production for feasibility testing in military aircraft. The project was assembling a newly patented Composite Focal Plane Array (CFPA) requiring precision epoxy die attach—video die on an AlNi substrate. A class 1000 clean room space was required. Assembly Services engineers developed a process and program which logged step by step into ADMA. The staff cleared a 300 sq ft portion of the lab behind two secured double doors. In this space: a 3500 Die Bonder, a 6500 Die Bonder and a GPD-Global dispenser were relocated to this ultra clean room. Assembly Services staff took particle counts several times a day for two weeks until the room met class 1000 requirements. Co-planarity of the video die array was imperative. The video die came in lots, with each lot often differing in height (+/- 3 um) that required the assembly process to compensate for this height difference. The WOFT indicates the required die and epoxy heights. The die was then picked and placed at a programmed height, force and time. While each array could be different in planarity, each separate array had to have the same co-planarity. Because ADMA housed the day-to-day assembly and process directions, technicians and operators were able to perform this work without a skilled engineer involved at every step. Before, during and after the assembly, the board was tested for shorts. After passive component attach, the board was tested again with a multi-meter for electrical soundness—all of the data was “pulled” into ADMA. ADMA can record and store ESD testing data—each particle count was pulled into the analysis picture for this project and delivered to the customer. If there was ever a problem, it was traceable and quickly fixed or re-worked. Fluctuations in material are common and part of working in micron-level assembly. It was discovered that the some of the substrates coming in from the customer were not accepting the epoxy effectively. The substrates were highly porous, rendering the entire process ineffective. Assembly Services combed through each lot via ADMA. The customer was able to see, with data, that their vendor had supplied an improper adhesive material. The process was not the problem. Quickly, the vendor shipped out the correct adhesives. The substrate material was reinstated and the process was back online. Inherent in this project was the need for traceability and data collection with every move. The final destination for this device was becoming part of a military aircraft—its requirements were ultra-high reliability. As work has continued on this project, the forecasts have been intermittent (a three-month forecasting build, dormant for two months, a six-month build, etc.). Nonetheless, it has been cost-effective for Assembly Services and for this customer to continue working together. BUILT IN BEST PRACTICES FOR GREATER PRODUCTIVITY Palomar Technologies bonders are used to build high-reliability assemblies for many of the largest technology infrastructure companies (military, RF/Wireless, optoelectronic). High quality and precise manufacturing are built-in to each piece of equipment and assembled product that leaves Palomar Technologies’ facilities. In high-precision and accuracy contract assembly services, ADMA is used to provide best-in-class documentation control, eliminating ambiguity that leads to waste. ADMA takes the guess work out of microelectronic packaging through documentation of all process steps—it acts

as a technical reference library for processes, improves training and enforces best manufacturing processes with minimal overhead. ADMA assists with materials kitting activities, acts as a central location for drawings, inspection data, build traceability, pass-down log functions and work instructions. Productivity loss and risk of inconsistency would be the result of not having production data in a central location that is easily referenced and clearly understood by technicians and engineers. For example, it took five minutes to perform a task in the previous paper environment; today with ADMA, it takes 30 seconds. Looking further into the ADMA supported best practices policy and built-in quality control processes, process clarity for technicians is where it all begins (see Figures 5a and 5b). Easy-to-follow instructions provide complete process clarity for workers by covering major steps and functions as a resource for fast retrieval of training and process information. ADMA prompts the staff:

• Where to get the materials • What to do with the materials • How to “go build this” • Clarification of “completeness and goodness” of product

A growing production laboratory can sometimes encounter staffing and training issues. In complex microelectronic packaging, training and acclimating new hires can be time consuming, expensive and risky. Historical production data combined with present-time instructions for operators reduces risk of staffing and training while ensuring delivery requirements are met. It is important to note that ADMA is not used for every customer, nor is it an extra cost for a customer. ADMA is simply a powerful organizational tool Assembly Services has centered its best practice policy around. A general observation would be an application “requiring traceability” (military, medical, and optoelectronic applications) plus a 3-6 month forecast would directly benefit from ADMA. Assembly Services provides “one-off” prototyping and testing services as well—these customers are not in need of historical data collection with forecasted builds. CLOSING THE FEEDBACK LOOP At the heart of traceability and best practices are all the details in between the beginning and end of the project. Tight process control is constantly monitoring to quickly identify the location of the deviation, isolating the issue and removing it, or reworking if the problem is systemic. The feedback loop indicates what is working and what is not. If a there is a minor crack in this loop, valuable information is at risk of being lost which can jeopardize schedule and customer satisfaction. Closing this loop, sealing it tight, and managing the device assembly details on a day-to-day basis is imperative. Complex assemblies may take multiple days, more than one shift and more than one operator to complete. ADMA enables complete pass-down continuity, or closed loop actions, from person to person and from shift to shift. For example, with wafer scale packaging on the rise and increasingly smaller die populated on wafers, continuity of work, in conjunction with the feedback loop, becomes essential. A key feature of ADMA is the overall improvement in the supply chain. In a wafer scale packaging process where ADMA is absent, chipped or problematic die have to be manually spotted and removed, or they are otherwise skipped over. With ADMA, not only are these problems located immediately, but they are also mapped, tagged and addressed. In a multiple shift operation, the ADMA software automatically stores the previous work, therefore eliminating duplication. This translates into faster turnaround times and quicker time-to-market for customers.

Situational Awareness 24/7 Assembly Services takes into account the reality of today’s microelectronic packaging environment: factories and management are rarely located in the same geographic place. ADMA enables situational awareness of the laboratory work environment, in managers’ offices and in conference rooms. Optimized as a paperless work environment—like a bank account—projects and materials are checked in and out of the system and status of build schedules, work orders and material inventories can be quickly evaluated. ADMA enables program supervisors and management to remotely or virtually monitor and manage the laboratory. Volumes of relevant data for making critical decisions are at the manager’s fingertips. In addition to evaluating the laboratory situation in real time, the data provided by ADMA includes running reports of consumable and non-consumable inventories, production efficiency rates, product completion times and notifications of areas where improvements can be made. Assembly Services’ general manager monitors work flows and data from his office and makes decisions such as assigning work flows, creating work flows, monitoring instructions, managing inventory and ensuring overall operational efficiency. Organic Growth Palomar Technologies’ Assembly Services was started in 2005, originally to meet customers’ growing need for applications work that exceeded the “pre-sale and paid applications” phase. Palomar Technologies answered that need by dedicating clean room space, a staff of process and application engineers and a general manager with over 20 years of microelectronics packaging experience. Assembly Service engineers are the best in the business; tested daily with the most difficult and complex micro-optoelectronic packaging assembly challenges. This has made the team a very robust and out-of-the-box engineering group. One customer commented “Palomar Assembly Services is the last house on the block – if no one can do it, they can.” These clean room spaces are qualified (class 1,000 to 10,000) and filled with Palomar Technologies’ tool kit of wire and die attach equipment in secure work areas. In addition to production equipment, the lab today houses test and measurement tools such as scanning electron microscope (for sub-micron measurement), video microscopes (Stereo Zoom), ultrasonic scanner and plasma cleaning. In 2008, alliances were made with GPD-Global, Royce Instruments and Hybond, Inc. Assembly Services lab was outfitted with a GPD precision dispensing system, a Royce pull tester and a Hybond manual bonder. ASSEMBLY SERVICES CUSTOMER PROFILES Assembly Services customers range from startup companies to established manufacturers that either do not currently wish to invest in high-accuracy wire and die attach machines or don’t have the staff and/or expertise to prototype, test and produce their complex devices. In other instances, Assembly Services customers simply don’t want the hassle of dedicating staff, training, expertise and floor space to a new program that requires high-accuracy wire and die attach. If and when the startup or established company chooses to move wire and die attach production to their own facilities, the transition is seamless and with very little, if any, downtime.. By the time the capital equipment transition-to-customer-facility is completed, the process development and kinks have been worked out by Assembly Services, and production continues (as if it were still back at Palomar Technologies in Carlsbad, CA). Production begins at the customer’s facility with an immense amount of learning already behind their product5. High-reliability and high-accuracy microelectronic packaging solutions are Assembly Services’ specialty. Applications such as MCMs, MEMS, HB LED, military and consumer MEMS, micro BGA, solar concentrators, active optical cables and chip on board (COB) are achieved using eutectic die                                                                                                                          5  If a customer decides to buy a bonder, ADMA is not included as it is an Assembly Services only tool; however the customer can commission Palomar to transfer aspects of it.  

attach, epoxy die attach, wire bonding and wafer scale packaging. Materials used in die attach applications range from AuGe, AuSn, AuSi, PbSn, conductive epoxies and non-conductive epoxies. The wire bonding portion of Assembly Services uses gold, platinum and aluminum materials. As customer needs progress, Assembly Services is in the unique position to quickly meet those needs as it functions under the same roof as its parent company, Palomar Technologies. This has enabled Assembly Services to offer true supply chain management services that handle customers purchasing, shipping and receiving and secure warehouse requirements. ADMA is one example of how Assembly Services is quickly meeting customers’ application challenges through innovating processes required in everyday microelectronic assembly production. Contact Palomar Technologies to receive more information about our advanced bonding equipment and process development, prototyping and volume contract assembly services. Contact: Julie Adams Palomar Technologies Assembly Services Worldwide Sales 760-931-3699 jadams@bonders www.palomartechnologies.com