Making the Switch from Printed Circuit Boards to Multi-Chip Modules for Deep Well Drilling: Frequently Asked Questions

by Jaymie Murray 2. September 2015 09:50

Traditionally the Oil & Gas industry used Printed Circuit Board (PCB) technology for down well, high-temperature electronics. As demands for higher reliability, longer life and durability in high temperatures in deep well drilling increases, it has been proven that conventional PCBs are no longer a viable solution.  Consequently, the industry is now embracing bare die in multi-chip module solutions (MCMs) in order to fully satisfy these requirements. However, some customers are weary of making the switch to a hybrid solution after relying on PCBs for so long and they often have concerns regarding costs, flexibility, and customisation. Here are a few questions customers frequently ask while contemplating transitioning to a hybrid solution.

Q: How do you justify the cost of switching to hybrids?

A: The transition to hybrid technology is often not driven by cost consideration. There are many reasons for adoption of hybrids:

  • Improved reliability
  • Improved performance – electrical and thermal
  • Significant size reduction
  • Ability to withstand harsh environments, including mechanical shock and vibration, temperature extremes and rapid temperature transitions
  • Improved electrical screening
  • Extended in-service life reduces total life cost

Q: What are the typical lead-times?

A:  There is normally a 20 week design cycle followed by 6 weeks for manufacture.

Q: Can MCM’s be reworked?

A: Rework processes are certified, qualified, and embrace a wide range of capabilities, including:

  • De-lid of module with subsequent hermetic re-lid after repair, and with usual fine and gross leak testing to verify the integrity of the seal
  • Semiconductor die removal and replacement
  • Passive component (resistors, capacitors and inductors) removal and replacement
  • Wire bond replacement
  • Thick film track repair with wire bonds or adhesives
  • Module can be re-sealed and re-tested

Q: How do you hybridise an existing PCB for high temperature operation?

A: There are several steps involved with customising an existing PCB in order to make it suitable for extremely high temperatures:

  • Supply the current BOM & Schematic: API will check bare die availability by taking the list of active components and checking with the OEM manufacturers if the part is available in bare die form required for C&W. API will provide feedback alternatives where necessary and work with you to fill any gaps in the circuit.
  • Define your environmental specification:  These specifications can include storage / operating temperature, shock & vibration requirements. API will check qualification data and confirm we have the required proven packaging techniques for your application, giving you confidence in the robustness of our packaging solution.
  • Define the space envelope: API will then perform an analysis based on your circuit to ensure we can physically fit the electronics in the space provided.
  • Define the package and I/O requirements: How will we mount the electronics in your tool? API designs custom mechanical package concepts that can remove the need for carrier PCBs not suitable for high temperatures.  I/O density is challenging in high temperature applications as often it can only be realised on the smaller of two sides of the package wall. API will review your I/O requirements and limitations and confirm if achievable. 
  • Convert the passives: Solderable termination / low temperature surface mount parts will need changing for high temperature and adhesive attach suitable for incorporation in a hybrid. API can print high temperature thick film resistors and recommend manufacturers with proven reliability.
  • Define your qualification plan: With no industry standards in place, how do you know what is best? API has an independent UKAS test house with experience in high temperature qualification plans, and we are able to review your environmental specifications and assist in defining a qualification plan.

Learn more about API’s high temperature hybrids and electronics at Offshore Europe 2015 at Stand 5B60 or visit http://micro.apitech.com/high-temperature-electronics to request a quote or contact us.

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