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Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

Wentao,

I don't have a lot of experience with that particular process, but I do believe based on what I read that MIP should be able to remove the layer.  If you haven't already, maybe talk to the guys at Jiaco.

Regards,

Chris

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

------------------------------
Wentao Qin
Engineer
Microchip Technology Inc.
Chandler AZ
------------------------------

Hello Wentao,

As Chris Mentioned, MIP should be able to remove the BCB since it is an organic polymer (I say should since I'm not going to just state this definitively, but I am quite positive MIP is your best option). You also need visible access to the area of interest so that the surface coating can be removed.

Another caveat is that you need to find an FA house that has a system, or to send your sample to Jiaco as a demo. In either case, if you contact someone at Jiaco they will tell you that there is one FA facility in the US that has a system.

I have knowledge of the process and would be willing to discuss it further privately.

------------------------------
Jason Loesch
Electrical Technician IV
Boston Scientific Corporation Inc.
Arden Hills MN

Original Message:
Sent: 05-25-2024 13:48
From: Wentao Qin
Subject: BCB Removal

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

------------------------------
Wentao Qin
Engineer
Microchip Technology Inc.
Chandler AZ
------------------------------

Hello Wentao,

As Chris Mentioned, MIP should be able to remove the BCB since it is an organic polymer (I say should since I'm not going to just state this definitively, but I am quite positive MIP is your best option). You also need visible access to the area of interest so that the surface coating can be removed.

Another caveat is that you need to find an FA house that has a system, or to send your sample to Jiaco as a demo. In either case, if you contact someone at Jiaco they will tell you that there is one FA facility in the US that has a system.

I have knowledge of the process and would be willing to discuss it further privately.

------------------------------
Jason Loesch
Electrical Technician IV
Boston Scientific Corporation Inc.
Arden Hills MN

Original Message:
Sent: 05-25-2024 13:48
From: Wentao Qin
Subject: BCB Removal

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

------------------------------
Wentao Qin
Engineer
Microchip Technology Inc.
Chandler AZ
------------------------------

Hi Chris and Jason,

I have just learnt that MIP had been tried by my colleague.

The first issue is that the MIP could no longer remove BCB after some time, likely due to some substances in the BCB accumulating and sealing the surface of BCB.

The 2nd issue is that the MIP recipe then started an ultrasonic cleaning to remove these substances, which can break the fragile die.

So we will try again the MIP until it no longer removes the BCB. We will then manually remove the substances accumulating on the BCB surface with a high-pressure stream of DI water, after which the MMIP will resume. Please let me know if you have any more feedback.

Thanks!

Wentao

Hello Wentao,

As Chris Mentioned, MIP should be able to remove the BCB since it is an organic polymer (I say should since I'm not going to just state this definitively, but I am quite positive MIP is your best option). You also need visible access to the area of interest so that the surface coating can be removed.

Another caveat is that you need to find an FA house that has a system, or to send your sample to Jiaco as a demo. In either case, if you contact someone at Jiaco they will tell you that there is one FA facility in the US that has a system.

I have knowledge of the process and would be willing to discuss it further privately.

------------------------------
Jason Loesch
Electrical Technician IV
Boston Scientific Corporation Inc.
Arden Hills MN

Original Message:
Sent: 05-25-2024 13:48
From: Wentao Qin
Subject: BCB Removal

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

------------------------------
Wentao Qin
Engineer
Microchip Technology Inc.
Chandler AZ
------------------------------

Wentao,

The MIP Recipe can be adjusted for no clean, or standard clean (as well as a few other options like 2X and 5X). No clean will keep the system from using the ultrasonic bath. From what I can tell, BCB alone doesn't have glass bead filler like other more "conventional" encapsulants, so using the clean cycle within the MIP may not be necessary at all or could be used sparingly/intermittently.

Also consider choice of location within the sample holder and mounting method will play a role in total length of time in the ultrasonic bath, and transferred ultrasonic energy to the DUT respectively - it may take some experimentation on a number of other variables as well (trying different settings for gasses, flow, dwell time, pattern and RF energy).

My suggestion is to call the MIP manufacturer to discuss your unique situation with them and ask for their advice. If your colleague is using a Jiaco system, they are receptive to these kinds of queries.

Finally, in the brief amount of time I have spent researching BCB, I did note several types / formulations of BCB are available - each one having some unique properties that may lend to use of chemical etchants like acetic acid or other chems recommended by the BCB manufacturer directly. A combination of techniques may be necessary here.

Hi Chris and Jason,

I have just learnt that MIP had been tried by my colleague.

The first issue is that the MIP could no longer remove BCB after some time, likely due to some substances in the BCB accumulating and sealing the surface of BCB.

The 2nd issue is that the MIP recipe then started an ultrasonic cleaning to remove these substances, which can break the fragile die.

So we will try again the MIP until it no longer removes the BCB. We will then manually remove the substances accumulating on the BCB surface with a high-pressure stream of DI water, after which the MMIP will resume. Please let me know if you have any more feedback.

Thanks!

Wentao

Hello Wentao,

As Chris Mentioned, MIP should be able to remove the BCB since it is an organic polymer (I say should since I'm not going to just state this definitively, but I am quite positive MIP is your best option). You also need visible access to the area of interest so that the surface coating can be removed.

Another caveat is that you need to find an FA house that has a system, or to send your sample to Jiaco as a demo. In either case, if you contact someone at Jiaco they will tell you that there is one FA facility in the US that has a system.

I have knowledge of the process and would be willing to discuss it further privately.

------------------------------
Jason Loesch
Electrical Technician IV
Boston Scientific Corporation Inc.
Arden Hills MN

Original Message:
Sent: 05-25-2024 13:48
From: Wentao Qin
Subject: BCB Removal

Hi Everyone,

I have a die coated with about 4 microns of BCB. Some Cu wires have reached and been embedded in the BCB layer. The BCB needs to be removed as part of the decapsulation, so that the die can be exposed for electrical FA. If you have had success to remove BCB, could you let me know how it is done?

One working method that I can find from the public domain is with aqueous or acetic acid solutions of ozone. The paper title is "Simple Removal Technology of Chemically Stable Polymer in MEMS Using Ozone Solution". One complication is the proper disposal of unused ozone.

Thanks,

Wentao

------------------------------
Wentao Qin
Engineer
Microchip Technology Inc.
Chandler AZ
------------------------------