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LinkedinOk so I ran the test of my PCB and try as I might the PCB was dead. Totally non-functioning. And to make matters worse, I would not have any clue of where the issue is. Could a static electric discharged have bricked the IC? Could some pad have a microscopic open circuit in its joint with the IC? Could there be a hidden short or open circuit somewhere that happened at some point? I simply have no way to know or test or find this issue. And this got me to thinking... maybe a bit bigger integrated IC chip would be better as you can visually see all connections, things are not so hidden between a chip and a PCB and impossible to inspect, you don't have hidden pads on the bottom to tap into, etc. I had seen some bigger integrated half bridge IC chips like this before and decided to investigate an alternative rather than start over or try to diagnose this failed PCB endlessly with hardly any way to even go about finding what was wrong...
So after some shopping I found the BTS7960 integrated half bridge IC chip. https://www.infineon.com/assets/row...fileId=db3a304412b407950112b43945006d5d&ack=t It has TO-263 form factor so this means actual pins come off the chip rather than having to try to solder to some tiny pads on the chip like we were dealing with on our CSD59950RWJ QFN style chip in my last post. This means EASY access to visibly see your solder joint, clear and large separation (comparatively) between traces, shorts being practically hard to achieve comparatively, and the need for microscopic precision of soldering and DIY board etching eliminated, the step of cutting out a viewing window on the bottom of the PCB to create access for manually soldered bus copper strips eliminated as now everything is truly single layer compatible with no need for a bootlegged DIY multi-layer strategy. So essentially, now my PCB etching can be VERY crude comparatively, so much so that even printing the PCB and transferring the print to the copper before etching becomes completely unnecessary. So much so that we can either manually just draw the PCB etching configuration with oil based markers or cut out the pcb traces/pads with a dremel by hand since everything is so big and crude we just don't need the precision to be much at all now. Everything is easy this way. Now is there a tradeoff or something we are losing? Not really that I can tell. These are 14mm long (including the pins)x 9mm wide and 4.4mm tall. I checked this next to my 2430 BLDC motor and 3 of these will still fit comfortably side by side along the can of the motor just like I had planned for the QFN chips. Also, the QFN chips after considering the breakout board PCB added length and width ended up close to the same dimensions all told as the bigger chip is so not a huge space savings there. And space savings are only relevant if they solve a space constraint. These bigger ones if they fit my constraints are not a liability or downside just for being bigger. The reduced manufacturing steps, complexity, and difficulty makes this far easier and faster to work with. It still offers 40a continuous which is VERY good and more than needed by a large margin for my motors. Also they were only $1.20 per chip which is about the same price point. So $3.60 per motor which is great IMO. Now these are discontinued/obsolete but I don't care the to-263 form factor and similar outputs is something I can find in other chips for similar pricing I believe so that won't be an issue I will be able to pivot later to those other options if needed later without any major design changes so its not an issue for me.
Does this mean I gave up? No. I basically just decided that trying my best, being very thorough and meticulous and careful I still somehow ended up with very hard to troubleshoot total failures this early in testing then really working with this QFN part is NOT that DIY friendly on a DIY PCB and starts reaching the limitations of what is practical. Even if doable it is hard enough to make it very hit and miss and time consuming and not worth that extra effort unless its necessary or there is not a far easier path that gives the same results faster/easier. And I now have a way faster and easier option that gives same results with NO tradeoff that is meaningful or moves the needle at all.
So I ordered 25 of these chips off aliexpress for now and 4 of them off amazon to work with while aliexpress is shipping slowly here. I'll have the 4 off amazon tomorrow while I wait for the larger order. I do this trick often paying more money for faster shipping on amazon while I wait for my slower shipping order at better price point in bulk to come and this avoids downtime waiting for shipments.
Oh and one more thing: I am considering going back to deadbugging with no PCB at all since this chip is so big and easy to connect to the chp itself can be considered to BE the PCB then. I'll just solder my wires to it then and not bother to even have a PCB. The PCB was moreso a way to breakout off the chip and give decent size solder points to connect my wires to etc but now that the chip is way bigger I don't need to breakout from it with a breakout board and can just attach the wires to its pins directly I feel. I can use 30ga wire wrapping wire to wrap to its pins for control wiring and use beefier wire soldered directly for power stage wiring. I might go with non SMD decoupling capacitors and resistors as well now.
Note: the amazon chips I bought as part of a module board for a h-bridge brushed dc motor driver setup. The idea there was to desolder the chips from that board to use for my project as that board is WAY too big for any practical purpose in a humanoid but its the two chips from that board that we are wanting to rob off of it.
So after some shopping I found the BTS7960 integrated half bridge IC chip. https://www.infineon.com/assets/row...fileId=db3a304412b407950112b43945006d5d&ack=t It has TO-263 form factor so this means actual pins come off the chip rather than having to try to solder to some tiny pads on the chip like we were dealing with on our CSD59950RWJ QFN style chip in my last post. This means EASY access to visibly see your solder joint, clear and large separation (comparatively) between traces, shorts being practically hard to achieve comparatively, and the need for microscopic precision of soldering and DIY board etching eliminated, the step of cutting out a viewing window on the bottom of the PCB to create access for manually soldered bus copper strips eliminated as now everything is truly single layer compatible with no need for a bootlegged DIY multi-layer strategy. So essentially, now my PCB etching can be VERY crude comparatively, so much so that even printing the PCB and transferring the print to the copper before etching becomes completely unnecessary. So much so that we can either manually just draw the PCB etching configuration with oil based markers or cut out the pcb traces/pads with a dremel by hand since everything is so big and crude we just don't need the precision to be much at all now. Everything is easy this way. Now is there a tradeoff or something we are losing? Not really that I can tell. These are 14mm long (including the pins)x 9mm wide and 4.4mm tall. I checked this next to my 2430 BLDC motor and 3 of these will still fit comfortably side by side along the can of the motor just like I had planned for the QFN chips. Also, the QFN chips after considering the breakout board PCB added length and width ended up close to the same dimensions all told as the bigger chip is so not a huge space savings there. And space savings are only relevant if they solve a space constraint. These bigger ones if they fit my constraints are not a liability or downside just for being bigger. The reduced manufacturing steps, complexity, and difficulty makes this far easier and faster to work with. It still offers 40a continuous which is VERY good and more than needed by a large margin for my motors. Also they were only $1.20 per chip which is about the same price point. So $3.60 per motor which is great IMO. Now these are discontinued/obsolete but I don't care the to-263 form factor and similar outputs is something I can find in other chips for similar pricing I believe so that won't be an issue I will be able to pivot later to those other options if needed later without any major design changes so its not an issue for me.
Does this mean I gave up? No. I basically just decided that trying my best, being very thorough and meticulous and careful I still somehow ended up with very hard to troubleshoot total failures this early in testing then really working with this QFN part is NOT that DIY friendly on a DIY PCB and starts reaching the limitations of what is practical. Even if doable it is hard enough to make it very hit and miss and time consuming and not worth that extra effort unless its necessary or there is not a far easier path that gives the same results faster/easier. And I now have a way faster and easier option that gives same results with NO tradeoff that is meaningful or moves the needle at all.
So I ordered 25 of these chips off aliexpress for now and 4 of them off amazon to work with while aliexpress is shipping slowly here. I'll have the 4 off amazon tomorrow while I wait for the larger order. I do this trick often paying more money for faster shipping on amazon while I wait for my slower shipping order at better price point in bulk to come and this avoids downtime waiting for shipments.
Oh and one more thing: I am considering going back to deadbugging with no PCB at all since this chip is so big and easy to connect to the chp itself can be considered to BE the PCB then. I'll just solder my wires to it then and not bother to even have a PCB. The PCB was moreso a way to breakout off the chip and give decent size solder points to connect my wires to etc but now that the chip is way bigger I don't need to breakout from it with a breakout board and can just attach the wires to its pins directly I feel. I can use 30ga wire wrapping wire to wrap to its pins for control wiring and use beefier wire soldered directly for power stage wiring. I might go with non SMD decoupling capacitors and resistors as well now.
Note: the amazon chips I bought as part of a module board for a h-bridge brushed dc motor driver setup. The idea there was to desolder the chips from that board to use for my project as that board is WAY too big for any practical purpose in a humanoid but its the two chips from that board that we are wanting to rob off of it.
