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Original question:

OPA2541: Number of MIL GRADE

OPA2541: test condition

Derek Zhong
Intellectual 470 points
Part Number: OPA2541

My customer used OPA2541SM in a specal product, they have a Particle Impact Noise Detection:
Customer Machine parameter:
VIBRATION SPECIFICATIONS:
Frequency Range：25 to 250 Hz, Sinusoidal
Other Vibration Modes：Limited Random, Flat Freq. 75 to 400 Hz
Automatic stepped Frequency from 40 to 250 Hz
Low Frequency Program：Maximum Amplitude Protection
Frequency Resolution：1 Hz
Time：0.1 to 25.5 Second per Program
Time Program Resolution：0.1 Second
Amplitude：0.1 to 25.50 'G' Peak, four digit display
Amplitude Program Resolution：0.1 'G'
Repeatability ：0.5 'G' Peak, with Feedback Control
*D.U.T. Weight ：Maximum 350 Grams over the entire range
*Maximum 400 Grams at 60 Hz（4511M4）

SHOCK SPECIFICATIONS:
Method ：Feedback Control of Shaker Armature
Adapts Shock to D.U.T. Weight
Amplitude ：Programmable 100 to 2500 'G'
Program Resolution： 10 'G'
Repeatability Within ：50 'G'
Pulse Width ：<100 Microsecond at 50% Amplitude
150-200 Microsecond at 10% Amplitude Shock Delay ：Settling time after Shock Programmable from 25 to 250 Msec

Our test condition Amplitude 1000G 60Hz Resolution 10g Time is 3s
At last we have tested 50pcs but 35pcs failure There is a foreign body in the cavity

Could you check the test condition for us? Thank you.

  • 0
    TI__Guru 54111 points

    Hi Derek,

    Q: At last we have tested 50pcs but 35pcs failure There is a foreign body in the cavity.

    I am unable to tell if OPA2541 has failed electrical and/or mechanical tests during vibration and/or shock impact test. "a foreign body in the cavity" sounds like a mechanical failure.

    Can you clarify the failure points? Is something snapped off during the test? 

    In the following, I assumed that you had mechanical failure in the part. Since this is a leaded part, you need to perform the following reinforcement.

    1. TO-3 package needs to be installed as close to the PCB as possible. Leave a minimum air gap between the base of can and PCB surface (it used to have a piece a silicon spacer between the can and PCB, but I am not sure that the technique is still used today). 

    2. Clean the perimeter of TO-3 can and PCB well with ethanol or IPA. Cover the perimeter of TO-3 package with epoxy and bond the edge of the package to the PCB surface around the IC (360 degree). Try to maximize the bonding and adhesion surface and cover good amount of adhesives between edges of TO-3 can and PCB surface (while maintaining certain appearance, consistency and good workmanship). And follow the recommended adhesive manufacturing instructions in mixing and curing (if prime is called out, please follow the adhesive application instruction per manufacture recommendation). 

    I suggested to use 3M  DP100 two part epoxy as an example. I used the product while I was in aerospace and it can handle vibration, shock impact, temperature , salt spray, humidity tests etc.. There are plenty similar two part epoxies on the market, but you need to select an adhesive that will meet your operating temperature range of the application. 

    The reasons to use adhesives are as follows. The TO-3 can has to "move" together with PCB board/EUT. Due to its mass, the package is required to bond onto a PCB surface/EUT that is bolted onto a vibration fixture or shock impact tray. So there is no additional movement or relative motion that TO-3 package is moving in opposite direction of PCB/EUT during the tests. 

    If this is electrical failure, please describe failure sequence from the vibration and shock impact test. The EUT should be powered on during vibration test. 

    If you have additional questions, please let us know. 

    Best,

    Raymond