Electronics > Manufacturing & Assembly

Modified LQFP land pattern to solve bridging problems (reflow only)

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Georgy.Moshkin:
Modern PCBs have a lot of dense surface mounted tiny components. I think majority do not use a simulator, and just stick to some IPC standards. I think, these standards may be derived from both experimentation and simulation (or calculations).

Georgy.Moshkin:
Modified USB Type-C land pattern for less bridging and easier stencil cleaning tested (https://youtu.be/JSf-CUBMFco)
Note that I used desoldered LQFP chip in this video (it already had some solder bridges), stencil was too thick, board jumped around a little during application, paste is expired, and heat plate was already hot. I think results with new paste and standard preheating in reflow oven will provide better results. USB Type-C connector was new and soldered very well.

NorthGuy:

--- Quote from: Georgy.Moshkin on July 12, 2023, 03:26:38 am ---Modified USB Type-C land pattern for less bridging and easier stencil cleaning

--- End quote ---

I use this USB connector and it has very good yield with standard footprint. If you get bridging, this must be because your stencil is too thick and deposits too much paste.

Georgy.Moshkin:
Yes, stencil is thick and I align it manually. Photo shows smeared paste before placement. This small stencil sheet is many times cheaper than normal stencil with aluminum frame. I just let the good manufacturing people use any sheets they have and not bothering them with demands on stencil thickness.

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