8 Replies Latest reply on Oct 6, 2016 11:34 AM by thkoc_1665816

Problem with Custom PCB

thkoc_1665816 Aug 13, 2016 1:13 PM

I crated a custom PCB to house CY8C4247LQI-BL483 chip with some custom components. The design around the chip is based on its datasheet (http://www.cypress.com/file/137466/download). The first board works without any problem. I can program it and see its advertising packets. However, on the second board, I can program it without any problem using the same program as in the first board but I cannot receive any advertising packets.

The problem may occur during soldering process. I used solder paste and heat gun method. Visual inspection sees no solder bridge or anything usual.

Is there any poor man's solution to check what went wrong? I do not have any expensive equipment to check other than a cheap digital volt meter and an old 15MHz oscilloscope. Is there a guideline to troubleshoot in this situation?

Thanks so much in advance. I really appreciate for your help.

1. Re: Problem with Custom PCB

rola_264706 Aug 13, 2016 5:43 PM (in response to thkoc_1665816)

Did you apply the solder paste with a solder mask? Or did you apply it by hand. That can result in excessive solder. A heat gun is not the best tool as you can apply too much heat to the parts. Also a multi meter is not usable for checking the RF section as it appears to be at ground. How about some pictures and you may need a microscope to check for solder bridges.
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2. Re: Problem with Custom PCB

BoTa_264741 Aug 13, 2016 7:40 PM (in response to thkoc_1665816)

Since chip is already soldered, I would go across all pins with soldering iron and wick to remove excessive solder. Apply generous amount of flux during procedure (practically pour it in top), then wash PCB with ethanol or acetone. Hope this helps.
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3. Re: Problem with Custom PCB

thkoc_1665816 Aug 14, 2016 6:12 AM (in response to rola_264706)

Thanks so much bobgoar. I applied the solder paste by hand. The PCB already have the green solder mask on. But yes, some of them end up with excessive solder that needed to be removed. May be a thin film with contact cutouts laying on top before applying solder paste may help. Unfortunately, I do not have a microscope. Just a big magnifying glass which is not good enough. I just hope that there is basic way to check. For example, check here you should see this voltage value, check there you should see that voltage value type of thing.
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4. Re: Problem with Custom PCB

thkoc_1665816 Aug 14, 2016 6:15 AM (in response to BoTa_264741)

Thanks so much odissey1. That's the method that I used to remove excessive solder especially when I saw a visible bridge. However, I never tried generous amount as your suggested yet. I will try soon.
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5. Re: Problem with Custom PCB

rola_264706 Aug 14, 2016 8:16 AM (in response to thkoc_1665816)

There is a few pins that you can check for voltage but as the part is mostly programmable that is not going to help much. You need a spectrum analyzer or a Network analyzer to troubleshoot the RF section. Can you send a picture of a board that you have not yet applied the parts to. It may be an issue with the assembly but it could also be the boards are not the same. I worked at antenna company and we made Spiral antennas and you would think that they would all work as they where just an etched board with a spiral on it. Some of them wouldn't work due to issues with the epoxy substrate.
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6. Re: Problem with Custom PCB

thkoc_1665816 Aug 15, 2016 3:34 PM (in response to rola_264706)

Thanks so much. I really appreciate for your help. Since i do not have good enough equipment, i will switch to ez-ble module instead.
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7. Re: Problem with Custom PCB

towec_1673171 Oct 5, 2016 2:30 PM (in response to thkoc_1665816)
Hi tkosiyat, have you had any luck on this issue? Or EZ-BLE module fixed your problem? I am having the same problem: 4 prototype boards are built, with CY8C4247LQI-BL483. A minimal BLE program, which only advertises and turns on one LED, is used. The program works on the demo kit (CY8CKIT-042-BLE) and one of the four identical boards, ie, transmitting advertisement packets which is detectable by CySmart. However, the other three boards can be programed but do not advertise. I also have a separate program which uses PWM, Op Amp, CapSense, I2C, etc, but not BLE, and every thing works on all four boards. Our hardware folks think since both 24MHz and 32KHz crystals are oscillating, it must be a software issue. I am at a loss and wonder if you have something to share. Thanks so much!!

prototype.jpg 2.0 MB
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8. Re: Problem with Custom PCB

thkoc_1665816 Oct 6, 2016 11:34 AM (in response to towec_1673171)

Eventually, I fully switch to EZ-BLE. In my case, I also switch to PRoC instead of PSoC. I used PSoC at first because I need to use opamps but it turned out that these opamps stop working if you put MCU into deep sleep mode. So, I add low-power opamps onto my circuit and switch to PRoC (EZ-BLE). All problems are gone since I do not have to worry about tuning crystals and checking RF signal using network analyzer (I do not have one since it is too expensive). All components including crystals sit in a very small footprint including PCB antenna. Both PWM and I2C work exactly the same as in PSoC. So, I hardly have to change anything on my software other than rearrange some pins.

In the end, I am very happy since I do not have to worry about BLE at all. It always work and the range is pretty good.
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