3 ms·
The important note is: 1. Longer leads of older packaging have higher parasitic inductance, parasitic capacitance, and parasitic resistance. Which hurts many e
by dragontamer 3y ago
The important note is:
1. Longer leads of older packaging have higher parasitic inductance, parasitic capacitance, and parasitic resistance. Which hurts many electronic designs.
2. The thermal pad on DFN / QFNs allows for direct-heat transfer off of the chip-package (while DIP, SOIC, and other older designs do NOT allow for this direct-heat transfer off). This improves thermals of hot parts, as you can use the whole PCB as a heatsink now, instead of having to add a heatsink elsewhere.
3. DFN and QFN are physically much smaller than traditional DIP, SOIC or TQFP packages. So people who use these smaller chip packages can make even smaller circuit boards, or alternatively, a more complex design fit in smaller spaces.
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QFN and DFN are very popular parts for modern professional level electronics. But do note that their small size and tiny leads make them harder to deal with at the hobbyist level. But its possible with enough flux, solder paste, and hot-air rework to work with these parts.
I would recommend that beginner electronics who are just getting into custom PCB design work with larger parts (like SOIC packages) instead. Bigger is often easier. Move to these tiny DFN or QFN parts only after you've gained confidence in your surface-mount skills.
- amelius 3y agoAny tips for handling BGA packages? Is it possible for hobbyists?
- dragontamer 3y agoI've never used a BGA unfortunately. My understanding is that BGA solder-balls come pre-attached to your chips in most cases. As long as you reflow-solder it on correctly on the 1st try, you're good. If you need to "fix" BGA, that's where things become very difficult for hobbyists. To do this, you need to unsolder the BGA with hot-air, lift it off, then "Reball" the BGA, which is equipment that likely hobbyists don't have. ------------ With regards to QFN or DFN vs BGA, I would expect BGA to be easier, as long as you've precisely made your soldermask to accept the correct sized solder-balls (which should be part of your chip's documentation). That is: BGA's hardest part is getting the board design just right. Especially because most BGAs require 4 or more layers before you can route all of the lines to them. In fact, the massive BGAs are physically impossible on anything less than 8 layer boards. ------------- Hobbyists won't have XRay equipment to see if the BGAs successfully worked either. So rework and quality-control are basically impossible. Your only hope is to "do it blind" and hope for the best. Which... is fine? Even BGA parts are relatively cheap. So build 3+ of your design at once. Have appropriate test-probes to take measurements during the "smoke test", and bam, you're good. One of those three tries is probably going to be successful.
- amelius 3y agoI wonder how you'd align them. The silkscreen is often not very precisely aligned to the copper layers, so you can't use markings in the silkscreen for alignment. Maybe use the top copper layer then instead? EDIT: I found this quite interesting video: https://www.youtube.com/watch?v=0KbINAq0hcU https://www.youtube.com/watch?v=0KbINAq0hcU