Pratical Design Details of Integrated Microwave Assemblies

[0dBc]

Hi all,

This question comes to all of the microwave gurus of edaboard. I would like to learn practical design details of integrated microwave assemblies (IMA). Where should I start? So far I have been designing RF PCBs with standard SMT components upto ~13 GHz using RO4000 series substrates. I did some research about high frequency microwave circuits and found out that Alumina is the preferred substrate. A lot of PCB manufacturers offer PCB stackups with RO4000 series, but I wasn't able to find any Alumina board processing house except this. Could you recommend any other companies for alumina board manufacturing?
There are a lot microwave capabilies brochures on the internet. Here is an example (page 12): https://ni-microwavecomponents.com/misc_docs/capabilities_brochure.pdf
Almost every brochure I found shows very similar metal carriers with (I suppose) alumina boards. Are these carriers a standart COTS item? If so where do you get them?
Is there any book on the practical aspects of IMA design? Or any company offering practical training on the subject?
Thanks in advance.

 

[Delta36]

**broken link removed**
http://www.thinfilm.com/

if you're looking to make a filter or some other circuit, you can use Alumina as the substrate, but you don't want to make the whole thing with alumina. It's brittle and will *****, so generally it's smaller things that are done on it, not full boards.

IMA's are usually custom. start with a block diagram design, buid up your circuits (generally bare die amps / attens / pin diode switches / and filters (alumina / rogers)), then build up a housing to enclose the circuits (brass works well for protos). Don't forget to put walls into the housing to channelize the different paths and keep a lid on it to keep the radiation inside and inside the channels.

learning really just comes from doing, on the job. I worked in IMAs for a long time, now I'm doing PCBs. They are two totally different ball games. Got any tips for me?

 

[0dBc]

Hi Delta,

Thanks for the reply. Since you already have experience with IMAs, designing RF/MW PCBs won't be a big challenge for you. I strongly recommend you to read the "Building a Microwave Frequency Synthesizer" article series by Chenakin. The articles are available online at www.highfrequencyelectronics.com. As you will see, RF/MW PCB design flow is quite similar to what you described above.

**broken link removed**
http://www.thinfilm.com/

if you're looking to make a filter or some other circuit, you can use Alumina as the substrate, but you don't want to make the whole thing with alumina. It's brittle and will *****, so generally it's smaller things that are done on it, not full boards.

IMA's are usually custom. start with a block diagram design, buid up your circuits (generally bare die amps / attens / pin diode switches / and filters (alumina / rogers)), then build up a housing to enclose the circuits (brass works well for protos). Don't forget to put walls into the housing to channelize the different paths and keep a lid on it to keep the radiation inside and inside the channels.

learning really just comes from doing, on the job. I worked in IMAs for a long time, now I'm doing PCBs. They are two totally different ball games. Got any tips for me?

 

[biff44]

alumina used to be popular, but you only see it nowadays when you have wirebonded unpackaged chips.