how to know what type of PCB/substrate is

[Leiser]

hi,

I have an LNA for a 2.2GHz application. I would like to know what type of PCB/substrate uses. Is there any way to know, measure for example dielectric contant.....

Thanks.

 

[Higgler]

Put up a pic on this site, someone may recognize it.
Ask the manufacturer.

Also, Google FR4 and click images on google.

If no luck, Google or check Rogers Corp and Taconic, get pics of their stuff, you'll probably recognize it.

You can measure it's dielectric properties, but it can be awkward and inaccurate.

 

[Comcokid]

If the LNA was made for any consumer or general commercial work, it is most likely a woven glass/epoxy or FR4. The term "FR4" has beecome a rather generic name. There are specific brands of glass/epoxy with a variety of dielectric constants and other material properties, but generally they have a dielectric constant of 4.2 to 5.5 . Color will generally be green, light-green, or slightly yellow.

Now, if it's for a bottom-end consumer throw-away made as cheaply as possible in high volume out of China, it might be made out of phenolic. Yes, I've seen ultra-cheap low GHz range done in phenolic. Color is generally brown to dark brown.

Now, if the board was made for high-end test equipment, high performance/low noise, or higher temperature application it could be one of a variety of teflon substrates - but this is rare. You will also find teflon (or some Rogers equivalent) in some TV satellite dish antenna LNAs. Color is generally tan to white.

 

[Leiser]

Thanks very much for you comments. For what I have seem it looks FR4. I have got some Arlon and Rogers boards and their substrate colour is tan to white whereas the board I am working with it is greenish.

NF specification for SDARS SIRIUS is 09dB. Frequency band is 2320 to 2332MHz and 32 dB gain .

Do you think it is possible to obtain that with FR-4.

 

[Higgler]

Many printed circuits have a protective green color soldermask that looks like paint. Here's a pic in the link that says it's Rogers material, and it's green.

http://www.alibaba.com/product-gs/371099138/HIGH_FREQUENCY_ROGERS_PCB.html

Take note if this is the green look of the board, you may need to scrape off the top solder mask with a dremel tool or exacto knife to actually see the board underneath.

 

[Leiser]

you are absolutely right, in fact, last friday I talked to a colleague and showed me a PCB made with Rogers material and looked like FR-4 as it had green soldermask. I did what you proposed, and scraped off the top solder and I saw the material underneath using a microscope and I compared it with Rogers and FR-4, for which I did the same. I found it difficult to distinguish them, all looked white.


I looked at the edge of the PCB and it is dark, not white as Rogers material.

 

[Higgler]

Rogers material is mostly dark, only their TMM material is white. I'm voting Rogers high frequency material.

FR4 has is typically a dark green.

Rogers makes an FR4 equivalent called 4003, which is much cheaper than their higher frequency boards.

My guess is your board is Rogers 4003.

 

[Leiser]

thanks for you comments. Just a question, what does TMM stand for?

I'll find out more information about Rogers 4003.

I attach a pic of the amplifier.

 

[Higgler]

Thermoset Microwave Material. Titles count alot in advertising. That's just a generic name. We heat it, we press it into a sheet and sell it as a Microwave Material.