Advanced photonic & microelectronic assembly: simple solutions for complex processes – An interview with Palomar Technologies

Die attach is a key process step in semiconductor packaging. It covers all devices across various applications and is a key contributor to assembly cost. The various mega trends such as big data, HPC, 5G, data centers, smart automotive etc. create demands for devices that require complex heterogeneous integration at package level and die attach technology has key role to play in it. Die attach equipment market is expected to grow at 6% CAGR from 2018-2024 to reach US$1.3 billion, according to the Die Attach Equipment Market report  published last year by Yole Développement (Yole).

Photonics is one area that has attracted strong interest for data center interconnects, long haul telecoms, 5G wireless access networks, LIDARs and other applications. The die attach process for photonics packaging is very complicated as it requires high precision alignment, delicate parts handling, handling of wide range of devices, various die attach technologies etc. The die attach equipment market for photonics packaging is expected to grow at 12% CAGR to reach ~US$213 million.

Palomar Technologies (Palomar) is one such company that delivers a Total Process Solution™ for advanced photonic and microelectronic device assembly processes. Palomar provides die attach equipment across a wide range of industries, covering various applications such as photonics, automotive (LiDAR & power modules), medical, microwave, RF/wireless, datacom, telecom and other niche markets.

Recently Santosh Kumar, Principal Analyst & Director Packaging, Assembly & Substrates, Yole Korea had the privilege to interview Daniel Evans, Chief Technology Officer at Palomar. Together they had the opportunity to discuss various topics including company’ history, products/services, photonics packaging challenges and more.

Santosh Kumar (SK): Could you please briefly introduce Palomar and its products /services?

Daniel Evans (DE): Palomar delivers a Total Process Solution™ for advanced photonic and microelectronic device assembly processes. With a focus on flexibility, speed and accuracy, Palomar offers Palomar die bonders, Palomar wire and wedge bonders, SST vacuum reflow systems, along with Innovation Centers for outsourced manufacturing and assembly, and Customer Support services.

SK: Could you also please detail your mission at Palomar?

DE: Palomar’s mission is to create simple solutions for complex processes. With today’s rapidly changing technology, time-to-market is one of the most important factors for success. We empower our customers to achieve success with their product introductions by offering our advanced packaging services to develop the processes and the equipment needed to help them transition from product prototype to volume production.

SK: Die attach is a key process step in IC assembly and covers all devices across various applications. Could you please describe the market segments Palomar Technologies is focusing on within the die attach business?

DE: Palomar provides die attach equipment across a wide range of industries. As your readers may know, Palomar has its roots in the Aerospace & Defense industry through our association with Hughes Aircraft. Over our 40+ years of supporting the semiconductor and photonics industries, we have expanded across automotive (LiDAR & power modules), medical, microwave, RF/wireless, datacom, telecom and a few niche markets.

The Palomar 3880 combined with the Musashi Aerojet provide a comprehensive solution for the next gen RF GaN power amplifier device manufacturers.

SK: Palomar Technologies is one of the main players for optoelectronics assembly in the die attach equipment business. According to you, what are the key challenges in optoelectronics assembly from the die attach perspective? How does your company address those challenges?

DE: One of the challenges for assembly of optoelectronic die attach is that each segment and each customer have specific packaging designs since there are no firm standards.  As a result of this, we work with customers in both multi-mode and single-mode optical designs.  We support VCSEL/PD designs for multi-mode, as well as many single mode designs for edge emitting lasers, heterogeneous designs, such as InP gain material to SiPIC prior to final semiconductor processing and hybrid designs like InP Laser to Carrier or InP Laser to SiPIC.

With such a wide diversity in designs, Palomar’s strategy to meet customers’ needs is to provide a family of flexible die bond equipment to accommodate optoelectronic assembly processes.  The equipment handles adhesive and solder based attachments for all of the different packaging mentioned and then some.

SK: Assembly/Packaging cost still makes up a significant portion of the total photonics device cost. What are the packaging trends, especially for Si photonics?  What are the main issues?

DE: The packaging and assembly challenges are related to the 6-degree-of-freedom control for sub-micron optical coupling of optical signals.  Si photonics is making tremendous headway in combining many discrete optical functions into monolithic planar structures.  However, Si Photonics is not able to provide efficient lasing technology.  Competing designs include InP platforms and Si Platforms; each with their own benefits.  Si photonics has the greatest promise of providing overall scalability and cost reduction.

The SST 8300 Series Automated Vacuum Pressure Soldering System, in single or triple chamber, utilizes SST’s unique system of applying both vacuum and gas pressure to achieve an extremely low-void rate for the soldering interface of key components inside a power module, especially for DBC-to-baseplate soldering.

Market leaders are pursuing Heterogeneous and Hybrid designs depending on their company history and available infrastructure.

The primary driver for volume products today is transceivers for telecom and datacom but it remains 100X smaller than the overall electronics market, making it difficult to attract significant investment.  Therefore, the market continues to draw upon electronic learning and technologies.

Package designs will continue to evolve and relax some of the coupling tolerances over time and that will help drive the cost down.

SK: What are the key packaging challenges for high- power RF devices dedicated to 5G applications?

DE: LDMOS and GaN technologies for base station power transistors require high thermal conductivity die attach methods to dissipate heat from the die.  LDMOS requires eutectic AuSi attachment, while GaN requires AuSn eutectic or pressure-less Ag sinter attachment.  To answer this latest trend in GaN attachment, we’ve developed a drop-in solution for pressure-less Ag-Sinter attachments to help our customers reduce changeover cost as they answer their own customers’ 5G requirements.  In the 5G packages we see, multiple die are still part of the package which makes Palomar’s  on-the-fly tool change for multiple dies sizes in a single package critical to maximize throughput and minimize time at temperature during assembly.

Palomar’s 3880 Die Bonder provides flexibility for eutectic or epoxy die attach as well as flip-chip applications.

In 2016, we developed Fixed Height Bond Line technology. Maintaining thermal and electrical performance with Ag sinter material requires that the height specified is met across the entire plane of the bond line without voids. Last year we further enhanced this solution by integrating Musashi’s Aerojet jet dispense pump. We made this decision after testing Ag sinter dispense Jet Dispense against Time-Pressure, Auger and Positive Displacement. The later three didn’t produce results we felt were satisfactory in terms of speed, bond line control and voiding.  Taking Palomar’s fixed height bond line technology and marrying it with jet dispense, we’ve been able to deliver a comprehensive solution for the next gen RF GaN power amplifier device manufacturers.

Using the same methodology, our roadmap includes a solution for adding another in-site measure for die tilt and bond line height. While our equipment is highly repeatable, adding another layer of automation and inspection of the machine’s work will give the users additional confidence in the build of their packages. As we see more RF GaN power packages moving outside of traditional Aerospace & Defense and Telecom applications into products like plasma ignition for cars and microwave cooking, our expectation is that there will be greater focus on automation and cost reduction.

SK: The die attach business is dominated by a few big players. How can Palomar Technologies maintain and enhance its position in this highly competitive market? Especially when we see cost pressure from customers becoming more and more important…

DE: A key differentiator for Palomar is our Total Process Solution, which not only includes more than our equipment, while we also maintain Innovation Centers around the world which specialize in prototyping, process development and contract manufacturing services to customers.  We are in the unique position in being able to work with a customer from start-up all the way through to volume production. As they transition to higher volume, we are able to easily satisfy their equipment requirements as the product has been developed, tested and produced using Palomar equipment. It’s a logical transition for the customer to move through our Innovation Centers to purchase their own Palomar equipment line.

SK: At Yole, we see consolidation going on in the assembly equipment business, including die attach activities. Players are diversifying their tools to support various business segments and assembly processes through M&As. According to you, will this trend continue in the future? How will it affect Palomar Technologies’ die attach equipment business?

DE: Palomar has a unique position in the market in that we design and manufacture die attach equipment, we also acquired SST International in 2015 to expand our product line to include not only Palomar die and wire bonders, and we now have a full line of vacuum reflow systems, making Palomar a broad supplier of a wide range of epoxy, eutectic, solder and sintering equipment.

We are proudly an independent USA-based company, owned and operated by local management.  Palomar will continue its strategic growth initiative through internal product developments or acquisitions.

SK: Palomar Technologies has a unique business model. Other than equipment business, Palomar Technologies also provides design, packaging process development and low volume contract manufacturing services to customers. Are there any plans for transition from LVM to HVM packaging services provider, as a full-fledged OSAT dedicated to niche segments?

DE: Palomar is positioned to grow our contract manufacturing services through the expansion of our Innovation Centers around the world. Our unique business model enables us to work with current and future giants in our industries with a clear focus on taking them from prototype to production of tomorrow’s technology through our design, process development and contact manufacturing. We work with the R&D departments of three of the five top internet providers and the top five defense contractors in the world.  Our strategy is to maintain our focus on being a Total Process Solution provider of both capital equipment and services for advanced optoelectronic and semiconductor packaging.

SK: i-Micronews’s team would like to thank you very much for this interview. Do you want to add few words to readers to end this discussion?

DE: I’d like to close by saying that Palomar is fortunate to have extremely talented and experienced employees and in our 40+ years, there is not much in this industry that we haven’t seen or been able to solve for our customers, so I would challenge your readers to bring us their optoelectronic packaging challenges and let us show you how we can help.


Daniel Evans, Chief Technical Officer for Palomar Technologies, is responsible for Applications Engineering, New Products, and Intellectual Property. Mr. Evans started his career at Hughes Aircraft (now Palomar Technologies) as a Design Engineer in 1984. Prior to being named CTO in 2015, he held the positions of Project Manager, Engineering Manager, VP of Engineering, and Applications Manager. Mr. Evans developed many of the core technologies fundamental to Palomar Technologies’ automated equipment platforms and has received nine Motion Control and System Patents, and has published over 30 technical papers.

Mr. Evans earned a B.S. in Mechanical Engineering from Purdue University, an M.S. in Mechanical Engineering from Stanford University (both degrees have an emphasis in Robotics and Controls), and a Certificate from the Executive Program for Scientists and Engineers at UCSD. He has served on the Advanced Packaging Roadmap Committees for iNEMI, IMAPS, and ITRS and regularly serves on IMAPS conference committees.


Santosh Kumar is currently working as Principal Analyst and Director Packaging, Assembly & Substrates, Yole Korea. Based in Seoul, Santosh is involved in the market, technological and strategic analysis of the microelectronic assembly and packaging technologies. His main interest areas are advanced IC packaging technology, including equipment & materials. He is the author of several reports on fan-out / fan-in WLP, flip chip and 3D/2.5D packaging.

Santosh Kumar received the Bachelor’s and Master’s Degrees in Engineering from the Indian Institute of Technology (IIT), Roorkee and University of Seoul respectively. He has published more than 40 papers in peer reviewed journals and has obtained 2 patents. He has presented and given talks at numerous conferences and technical symposiums related to advanced microelectronics packaging.

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