About Us

About Us

Microelectronics Assembly, Process Development, NPI and Volume Contract Manufacturing

Promex combines broad technical capabilities, in-depth process knowledge, materials-centric advanced packaging and microelectronics assembly expertise with scalable manufacturing capacity to fast track new medical and bioscience products to volume production, all from one centralized facility in the heart of Silicon Valley. Promex's value starts by allowing customers the sequential steps of prototyping through volume production. Our world class microelectronics assembly knowledge, process flows and automated equipment sets allow reduced time-to-market in a partnership focused culture.

Two duplicate RoHS optimized SMT lines combined with Class 100 and Class 1000 clean rooms provide fully controlled process flows for high reliability medical device PCBA assembly, including Class III implantable devices. This SMT capability can often be integrated to implement today's complex multi technology medical devices.

  • • Medical device microelectronics assembly
  • • Custom process development
  • • New product introduction (NPI)
  • • SMT/PCBA
  • • IPC-A-610 Class 3 assembly
  • • Implantable medical devices


Products, including Medical Electronic and Biotech Products, can be built in 2 ways;

  • • as individual lots, or batches that are generally processed as a group in a series of sequences
  • • in a continuous flow process where a small groups of devices, often a single unit, are processed and then passed on to the next process in an assembly line like flow.

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Small quantities that are manufactured infrequently are usually built using the batch process. Higher volumes are usually built in a continuous flow process where

Turnkey materials procurement and supply chain management is available



Implantable Devices

These devices utilize electronics that can be integrated into a small module which provides functions over extended life and can be easily implanted. Size, compatibility with the living human body and compatibility with the surgery process drive the package features.


Key Requirements Include

  • • FDA approved class three materials and processes
  • • Mixed, complex assembly
  • • Integration of multiple die and part types
  • • Complete, thorough documentation

Promex is able to provide the following capabilities that are specific to implantable devices:

  • • Provide trained operators and complete documentation packages
  • • Process flex circuitry including
    • ◘ SMT assembly
    • ◘ Direct chip attach using flip chip or chip-on-board (COB)
    • ◘ Process flex circuitry including folding circuitry
  • • Mount small parts
    • ◘ 02001 and 010005 SMT parts
    • ◘ Flip chip and COB
  • • Cleanliness
    • ◘ Water soluble flux to minimize residue
    • ◘ Ionography verification
  • • Material traceability
    • ◘ Incoming inspection and documentation
    • ◘ Part & substrate serialization
  • • Review of your design to minimize cost and improve reliability and manufacturability.

The above capabilities are needed to successfully build modern implanted devices. The substrates used for the electronics for these products are often rigid-flex structures mounted within a rigid circuit board frame that holds the flex circuitry flat to enable straightforward SMT assembly. Substrates are subsequently removed from the rigid frame and often folded into a stack to minimize area and fit into a specific form factor. These devices utilize 0201 and 01005 parts, direct chip attach, micro BGAs’ and other classes of small parts to minimize the physical size. Those high density products require small solder pads with solder mask that has excellent registration and through board vias that are tented, at least near other solder pads.


Several sets of fiducials enable cameras on placement equipment to accurately load parts. A universal set of fiducials in the form of circles 1 to 2 mm in diameter for each unit are helpful. Additional sets of fiducials near parts that have tight placement requirements ensure correct placement.


Drying of the substrate and parts before placement and the necessary reflow is important to minimize delamination of both parts and substrates. Delamination can lead to long term reliability issues. CSAM (computerized scanning acoustic microscopy) is an effective tool to detect delamination in many structures.


Water soluble fluxes are best for this class of product and work well with either Sn63 solder, that can still be utilized for medical devices, or a RoHS alloy, such as SAC 305. No-clean fluxes that eliminate the wash cycle are not recommended.


Excellent cleaning of finished assemblies to remove any potential contaminant is important to maximize long term reliability. Thus, monitoring of wash water and cleanliness verification with an ionograph are important.


Since these devices are usually packaged in a welded titanium “can”, part placement to avoid exposure to the high temperatures inherent in welding is important, especially placement of the battery.


If devices are sterilized with ionizing radiation, the components and materials must be tolerant of that radiation and not become brittle or, for optical chain materials, change in optical clarity, index of refraction or color.



Medical Treatment Devices


Devices which utilize imaging, energy delivery, and sensing into treatment systems used during procedures. These include devices to assist in treatment like cameras or to provide treatment like laser ablation, ultrasound disruption, mechanical manipulation, etc. Also, these devices can provide additional monitoring in the body during a procedure.


The Key technology requirements for this class of product are:

  • • Ability to integrate sensors of different types into small assemblies
  • • FDA compliant manufacturing processes
  • • Optical assembly
  • • Precision placement of complex stacked assemblies
  • • Encapsulation
  • • Ability to handle sterilization processes

Promex is able to provide these capabilities that are specific to Medical Instruments:


  • • Provide trained operators and complete documentation packages
  • • Assemble devices in particle controlled environments; class 100, 1,000 or 10,000.
    • ◘ Wet bench cleaning
    • ◘ Plasma cleaning
    • ◘ Adhesive part assembly
      • ► Die attach with a variety of adhesive dispensing methods
      • ► Optical element assembly with thermally cured and UV adhesives
      • ► Mechanical element assembly with various adhesive dispense methods
    • ◘ Wire bonding
    • ◘ Die Placement
      • ► +/- 6 micron accuracy
      • ► Pick die and other components from
        • • waffle pack
        • • wafer as sawn on tape
      • ► Variety of die attach materials and methods
        • • Dispensed epoxy, both conductive and non-conductive
        • • Stamped epoxy, both conductive and non-conductive
        • • Die attach film (DAF)
      • ► Die adhesive fillet and void control
        • • DAF to minimize voids
        • • Engineered dispense pattern to minimize voids and control fillets
        • • CSAM and X-ray to verify results
    • ◘ Controlled, high accuracy dispensing
      • ► Adhesives
      • ► Sealants
      • ► Die attach materials
      • ► Solders
      • ► Encapsulants
    • ◘ Mechanical Nexiv measurements
      • ► Automated, dimensional X, Y Z and theta measurements to +/- 1 micron and +/- 0.1 degree accuracy
      • ► Automated file generation
    • ◘ Electrical testing & data collection
    • ◘ Packaging for shipment
      • ► Sealed in final container in cleanroom environment
  • • SMT assembly
    • ◘ Conventional SMT part placement on a variety of substrates
      • ► FR-4, FR-5
      • ► Thick Film Ceramic
      • ► Thin Film Ceramic
      • ► Flex circuitry
      • ► Rigid flex circuitry
    • ◘ Mixed assembly on the above substrates
      • ► Conventional SMT
      • ► Direct chip attach with flip chip or chip-on-board (COB)
    • ◘ Water soluable fluxes to minimize residue
  • • Mount small parts
    • ◘ 02001 and 010005 SMT parts
    • ◘ Micro BGAs
    • ◘ Chip Scale Packages (CSP)
  • • Material traceability
  • • Review of your design to minimize cost and improve reliability and manufacturability.

These capabilities are needed to build modern treatment devices, particularly image sensors


Modern Image Sensors have very small pixels; on the order of a few microns. Thus, they are highly susceptible to particulate contamination. A single particle on a sensor that impedes light reaching even a portion of a pixel may result in an image that has unacceptable defects. While image processing can sometimes mitigate imperfections resulting from particles, that is not always true. Thus, image sensors must be manufactured utilizing processes that eliminate particle contamination. That implies good cleaning processes, processing in low particulate environments, such as class 100 and class 100 cleanrooms, storage of work-in-process in controlled environments and careful packaging of finished products.


The light detecting sensor die should be sealed in a cavity to minimize potential particle contamination of the sensor. Before the sensor is sealed in a manner that prevents particulate contamination, the sensor should be optically and electrically tested at a stage where any particle can be removed.


The chips that process information from image sensors often consume a significant amount of power and thus require excellent thermal design. The use of thin die, highly thermally conductive substrates such as circuit boards with copper planes and thin, highly conductive die attach materials such as die attach film (DAF) all improve thermal performance.



Diagnostic Equipment


Devices are used for detection and analysis of samples in lab and hospital setting. Many are low volume applications 100’s to 10,00O’s per year. They may use optical, thermal, or electrical detection mechanism which mix optical and electronics in a small format detector.


Key technology requirements


  • • Integrated optics with bare die and SMT mixed
  • • Fine pitch features
  • • Custom optical path design
  • • Lens and filter integration
  • • Fluid flow and control

Promex is able to provide these capabilities that are specific to Diagnostic Equipment:


  • • Provide trained manufacturing operators and complete documentation packages
  • • Assemble Devices in particle controlled environments; class 100, 1,000 or 10,000.
    • ◘ Wet bench cleaning
    • ◘ Plasma cleaning
    • ◘ Assemble and seal interfaces for
      • ► Parts molded in polymers
      • ► Machined parts
      • ► Optical elements
      • ► Chips with specific chemistries
      • ► Electronic substrates
    • ◘ Adhesive part assembly
      • ► Mechanical elements with various adhesive dispense methods
      • ► Optical elements with thermally cured and UV adhesives
      • ► Diagnostic chips that require special processing
    • ◘ Wire bonding
    • ◘ Die and similar part Placement
      • ► +/- 6 micron accuracy
      • ► Pick die and other components from
      • ► Variety of attachment materials and methods
      • ► Adhesive fillet and void control
    • ◘ Controlled, high accuracy dispensing of medical and biocompatible organics for sealing and fluid flow control
      • ► Adhesives
      • ► Sealants
      • ► Die attach materials
      • ► Encapsulants
    • ◘ Mechanical Nexiv measurements
      • ► Automated, dimensional X, Y Z and theta measurements to +/- 1 micron and +/- 0.1 degree accuracy
      • ► Automated file generation
    • ◘ Leak, Electrical and Optical testing & data collection
    • ◘ Packaging for shipment
      • ► Sealed in final container in a cleanroom
  • • SMT assembly
    • ◘ Conventional SMT part placement on a variety of substrates
      • ► FR-4, FR-5
      • ► Thick Film Ceramic
      • ► Thin Film Ceramic
      • ► Flex circuitry
      • ► Rigid flex circuitry
    • ◘ Mixed assembly on the above substrates
      • ► Conventional SMT
      • ► Direct chip attach with flip chip or chip-on-board (COB)
    • ◘ Water soluable fluxes to minimize residue
  • • Mount small parts
    • ◘ Molded or machined flow control parts
    • ◘ 02001 and 010005 SMT parts
    • ◘ Micro BGAs
    • ◘ Chip Scale Packages (CSP)
  • • Material traceability
  • • Review of your design to minimize cost and improve reliability and manufacturability.

These Diagnostic Devices typically utilize fluids in small channels, optical chains to control light to determine molecular bonding and sometimes chemistry to tag or detect certain molecular species. Thus, these devices are primarily fluidic assemblies with optical and electronic assemblies as well. That implies that fluid sealing, electrical isolation, cleanliness, particle control, optical transparency and long term stability are all important. Many of these functions are provided by utilizing organic materials such as adhesives to join parts, encapsulants to seal parts, coatings to prevent contact and to provide isolation. These organics are deposited in a variety of ways; manual or automated dispensing, as films applied to parts before placement or by stencil or screen printing. The precision and control required make automation an attractive option.


These devices also often have unique requirements. These might include never exceeding a temperature of, say, 85 C during assembly or handling die with chemistry on them implying that the active surface cannot be touched in any manner or exposed to cleaning processes such as a water wash.


To achieve the reliability and long life necessary in some of these fluid processing devices, excellent adhesion between surfaces and the elimination of voids or bubbles in organics during manufacture are critical. Selection of suitable materials, cleaning processes and surface preparation prior to sealing are important to avoid long term leakage and ensure stable performance.

Disposable Diagnostic Devices including DNA Processing Devices


These devices are used for a single run of a medical or biologic sample to detect DNA, bacteria, blood chemistry, lactose, blood sugar, etc. They often require combining sample handling, which can be wet , with electronics and sensors in a small, low cost a device. Part can be made in separate processes (injection molding, semiconductor, and packaging) but need to be integrated/assembled in a highly scalable manufacturing process.


The Key Technology Requirements for these devices are:


  • • Microfluidics with either molded or etched forms
  • • Assembly requires sealing to control fluid flow combined with electronics in a SIP
  • • Low cost assembly process
  • • A process scalable to very high volumes
  • • Pricing that can scale from $100’s to $10’s

Promex is able to provide these capabilities that are specific to Disposable Diagnostic Devices:


  • • Provide trained operators and complete documentation packages
  • • Assemble Devices in particle controlled environments; class 100, 1,000 or 10,000.
    • ◘ Wet bench cleaning
    • ◘ Plasma cleaning
    • ◘ Assemble and seal interfaces for
      • ► Parts molded in polymers
      • ► Machined parts
      • ► Fluid control channels
      • ► Optical elements
      • ► Electronic substrates
    • ◘ Adhesive part assembly
      • ► Mechanical elements with various adhesive dispense methods
      • ► Optical elements with thermally cured and UV adhesives
    • ◘ Wire bonding
    • ◘ Die and similar part Placement
      • ► +/- 6 micron accuracy
      • ► Pick die and other components from
        • • waffle pack
        • • wafer as sawn on tape
      • ► Variety of attachment materials and methods
        • • Dispensed epoxy, both conductive and non-conductive
        • • Stamped epoxy, both conductive and non-conductive
        • • Die attach film (DAF)
      • ► Adhesive fillet and void control
        • • DAF to minimize voids
        • • Engineered dispense pattern to minimize voids and control fillets
        • • CSAM and X-ray to verify results
    • ◘ Controlled, high accuracy dispensing of medical and biocompatible organics for sealing and fluid flow control
      • ► Adhesives
      • ► Sealants
      • ► Die attach materials
      • ► Encapsulants
    • ◘ Mechanical Nexiv measurements
      • ► Automated, dimensional X, Y Z and theta measurements to +/- 1 micron and +/- 0.1 degree accuracy
      • ► Automated file generation
    • ◘ Leak, Electrical and Optical testing & data collection
    • ◘ Packaging for shipment
      • ► Sealed in final container in cleanroom environment
  • • SMT assembly
    • ◘ Conventional SMT part placement on a variety of substrates
      • ► FR-4, FR-5
      • ► Thick Film Ceramic
      • ► Thin Film Ceramic
      • ► Flex circuitry
      • ► Rigid flex circuitry
    • ◘ Mixed assembly on the above substrates
      • ► Conventional SMT
      • ► Direct chip attach with flip chip or chip-on-board (COB)
    • ◘ Water soluable fluxes to minimize residue
  • • Mount small parts
    • ◘ Molded or machined flow control parts
    • ◘ 02001 and 010005 SMT parts
    • ◘ Micro BGAs
    • ◘ Chip Scale Packages (CSP
  • • Material traceability
  • • Review of your design to minimize cost and improve reliability and manufacturability.

These devices have much in common with Diagnostic Equipment, they often have additional requirements often driven by the high volumes anticipated.



Personal Health Devices including Wearables


Things that consumers can use on their own to monitor health and are moving to the wearable market over time. These require mixed assembly and often start at low volumes depending on the end market. They require some type of sensor or sensors combined built using a mix of assembly technologies.


Key Technology Requirements


  • • Simple assembly which can be low cost
  • • Lower operating life requirements
  • • Small form factor to enable wearable units
  • • Shapes that allow for fashion designs
  • • Rugged, robust construction to tolerate consumer use

Promex is able to provide these capabilities that are specific to Personal Health Devices including Wearable that incorporate electronics:


  • • SMT assembly
    • ◘ Conventional SMT part placement on a variety of substrates
      • ► Flex circuitry
      • ► Rigid flex circuitry
      • ► FR-4, FR-5
    • ◘ Mixed assembly on the above substrates
      • ► Conventional SMT
      • ► Direct chip attach with flip chip or chip-on-board (COB)
    • ◘ Water soluble fluxes to minimize residue
  • • Mount small parts
    • ◘ 02001 and 010005 SMT parts
    • ◘ Micro BGAs
    • ◘ Chip Scale Packages (CSP)
    • ◘ Molded or machined flow control parts
  • • Assembly of Devices in particle controlled environments; class 100, 1,000 or 10,000.
    • ◘ Wet bench cleaning
    • ◘ Plasma cleaning
    • ◘ Assemble and seal interfaces for
      • ► Mechanical elements with various adhesive dispense methods
      • ► Optical elements with thermally cured and UV adhesives
    • ◘ Adhesive part assembly
      • ► Parts molded in polymers
      • ► Machined parts
      • ► Optical elements
      • ► Electronic substrates
    • ◘ Wire bonding
    • ◘ Place Die and odd form factor parts
      • ► +/- 6 micron accuracy
      • ► Pick die and other parts from
        • • waffle pack
        • • wafer as sawn on tape
      • ► Attach parts with a variety of materials and methods
        • • Dispensed epoxy, both conductive and non-conductive
        • • Stamped epoxy, both conductive and non-conductive
        • • Die attach film (DAF)
      • ► Control fillets and voids
        • • DAF to minimize voids
        • • Engineered dispense pattern to minimize voids and control fillets
        • • CSAM and X-ray to verify results
    • ◘ Controlled, high accuracy dispensing of medical and biocompatible organics for sealing and fluid flow control
      • ► Adhesives
      • ► Sealants
      • ► Die attach materials
      • ► Encapsulants
    • ◘ Mechanical Nexiv measurements
      • ► Automated, dimensional X, Y Z and theta measurements to +/- 1 micron and +/- 0.1 degree accuracy
      • ► Automated file generation
    • ◘ Leak, Electrical and Optical testing & data collection
    • ◘ Packaging for shipment
      • ► Sealed in final container in cleanroom environment
  • • Material traceability
  • • Review of your design to minimize cost and improve reliability and manufacturability.
  • • Provide trained operators and complete documentation packages

Personal Health Devices and Wearables must be rugged and tolerate environmental extremes. Among the requirements are compatibility with; temperatures from -40C to + 85C; water immersion; organic contamination such as sunscreen, soap, etc. ; multiple drops on hard surfaces; twisting and bending; low cycle fatigue; etc.