• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 40 subscribers
  • Views 159 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

WL1835MOD: Shorting issue in WL1835

Tapan Patel
Prodigy 10 points
Part Number: WL1835MOD
Other Parts Discussed in Thread: WL1835,
Currently, we are using wifi mod WL1835 in one of our designs. We are facing some shorting issues in between I/O pins after the reflow process. As per the attached datasheet, you have recommended SMD (Solder Mask Defined) pads for the footprint but in our design we have used NSMD (Non-Solder Mask Defined ) Pads, having land pattern data mentioned below,
 
FOR I/O PINS
1. Copper Pad (used in our design)---- 0.4mm X 0.75mm
    Copper Pad (as per datasheet)---- Not defined in datasheet
2. Paste Pad (used in our design)---- 0.33mm X 0.75mm with  Radius of 0.16mm
    Paste Pad ( as per datasheet  )---- 0.4mm X 0.75mm with Radius of 0.05mm
3. Open Solder Mask Pad (used in our design)---- 0.46mm X 0.81mm
    Open Solder Mask   ( as per datasheet  )---- 0.4mm X 0.75mm
    
FOR 4 CORNER PADS
1. Copper Pad (used in our design)---- 0.75mm
    Copper Pad (as per datasheet)---- not defined in datasheet
2. Paste Pad (used in our design)---- 0.52mm
    Paste Pad ( as per datasheet  )---- 0.713mm
3. Open Solder Mask Pad (used in our design)---- 0.8mm
    Open Solder Mask   ( as per datasheet  )---- 0.75mm
FOR 36 THERMAL PADS
1. Copper Pad (used in our design)----  1mm square pad
    Copper Pad (as per datasheet)---- not defined in datasheet
2. Paste Pad (used in our design)---- 0.7 mm
    Paste Pad ( as per datasheet  )---- 0.95mm
3. Open Solder Mask Pad (used in our design)---- 1.06mm
    Open Solder Mask   ( as per datasheet  )---- 1mm
Does NSMD pad create any shorting issue?? Or any other suggestion to avoid shorting issues between I/O pins? The shorting issue is happening between  I/O pins only.
  • +1
    TI__Mastermind 34880 points

    Hi Tapan,

    Ill reach out to our packaging team and get back to you by next Tuesday/Wednesday.

    BR,

    Seong

  • 0 in reply to Seong Kim
    TI__Mastermind 34880 points

    Tapan,

    The WL1835MOD is a 0.7mm pitch package. The pad width is 0.4mm and the gap between pads are 0.3mm

    NSMD has better solder joint reliability because solder wrap around the PCB pad. Disadvantage is the trace connection to the pad could cause inconsistent solder pad dimension, depends on trace width. A thick trace could cause solder short between trace to pads.

    SMD restrict the total exposed solder area. So the dimension of all solder joints are consistent.

    Another factor that can cause solder short is component placement. If placement use component thickness, the suggestion is to add 0.05mm to actual component thickness so that the package will sit half way into the paste instead of all the way down.

    Putting too much pressure on the solder paste and squeeze them out.

    If component placement use force release, the suggestion is to use minimum force which is less than or equal to 3N.

    BR,

    Seong