Microcontroller shielding

[Adwaittronics]

I have RF application board / PCB with RF frequency range of 134MHz to 174MHz ,where RF module is used and the module is shielded .
But I want to shield the Microcontroller on the PCB too ,Can any one suggest a suitable metal material for shielding ?
Also problem is , I don't have any provision to solder the metal shield to the PCB so is there any other way where i can use metal film or foil or sheet for shielding without soldering it to board.

 

[FvM]

Not sure if the idea makes sense at all. Shielding is primarily used to suppress radiated emissions. I won't expect much radiated emission from a small controller section on a PCB. Most emissions are conducted through signal and power supply connections and radiated else where. So in any case, shielding is useless without strict filtering of all potentially RF carrying PCB traces. I presume, if you don't have provisions to solder a shield case, you neither provided filter options.

Placing metal sheets above and below the microcontroller section and soldering it to multiple circuit ground nodes can give a certain shield effect. Personally I won't apply it unless I have previously identified a serious local RF emission with a spectrum analyzer and sniffer probe.

 

[Adwaittronics]

Not sure if the idea makes sense at all. Shielding is primarily used to suppress radiated emissions. I won't expect much radiated emission from a small controller section on a PCB. Most emissions are conducted through signal and power supply connections and radiated else where. So in any case, shielding is useless without strict filtering of all potentially RF carrying PCB traces. I presume, if you don't have provisions to solder a shield case, you neither provided filter options.

Placing metal sheets above and below the microcontroller section and soldering it to multiple circuit ground nodes can give a certain shield effect. Personally I won't apply it unless I have previously identified a serious local RF emission with a spectrum analyzer and sniffer probe.

Thanks.
I have taken some precautions on the board like separating RF section from rest of the circuitry and providing filtering caps to controller and to where its necessary else where and providing proper Grounding but still I want to protect the controller from external radiations.

 

[FvM]

protect the controller from external radiations

Rarely necessary.

For the UHF and microwave range, RF absorbing foam and ferrite sheets may be an option.

 

[BigBoss]

Since the RF stage is well shielded, why the uC will need an extra shielding ?? If Decoupling and Grounding is well deployed, it'll be sufficient.

 

[KlausST]

Hi,

I also don't think that shielding of the microcontroller is useful.

Does the HF cause problems now?
* Yes: what problems? Can we see your PCB layout?
* No: why bother?

Klaus

 

[biff44]

without soldering to a board with a nearly unbroken ground plane layer, any sort of metal "shield" you install will have little benefit. It has to be designed in right from the start to have an effective EMI filter.

AND your RF frequency range of interest is so low, it might not help to add absorber materials.

Assuming you can not do a board relayout....maybe inspecting the DC power supply bypass capacitors used would help. Possibly going to one with a higher self resonant frequency will lower the amount of spike noise on the DC bus. For example, lets say there is a .1 uF capacitor on the DC line into the microprocessor...maybe you can find a 10,000 pF one that has much better RF performance, and will stop the spike energy from propagating along the PC board traces.

 

[speedEC]

You can shield entire PCB using shielding paint on the enclosure of the PCB unit but you have to put antenna in proper place to protect the unit from shield interference. You can see this in scan machines. But cost also high compared to metal shields.

hope this helps.
pmk

 

[jingyiprecision]

I have RF application board / PCB with RF frequency range of 134MHz to 174MHz ,where RF module is used and the module is shielded .
But I want to shield the Microcontroller on the PCB too ,Can any one suggest a suitable metal material for shielding ?
Also problem is , I don't have any provision to solder the metal shield to the PCB so is there any other way where i can use metal film or foil or sheet for shielding without soldering it to board.

Normally the material of shielding is tinplate or nickel silver ,both easily to solder ,It's depend on your needs .

[Link to commercial website deleted.]

 

[biff44]

I have RF application board / PCB with RF frequency range of 134MHz to 174MHz ,where RF module is used and the module is shielded .
But I want to shield the Microcontroller on the PCB too ,Can any one suggest a suitable metal material for shielding ?
Also problem is , I don't have any provision to solder the metal shield to the PCB so is there any other way where i can use metal film or foil or sheet for shielding without soldering it to board.

So, you screwed up! respin the board to use a shield over the micro and any external digital clock. Cover the whole thing with one of these. Make sure there are bypass caps under the shield for supply lines. And try to get a full solid metal ground plane under the micro, and tons of via holes from that ground plane to the metal shield.

https://leadertechinc.com/product/one-piece-surface-mount-shields-2/