LQFP Layout in 45º Degree

[Inka_One]

Hi Folks!

I'd like to know why components with LQFP package must be layouted in 45° degree. I have seen so many PCBs with this footprint layouted in 45º degre. Is it anything special or just defaul?

Thank a lot for the answers!

 

[Jos Brink]

i don't think it's a must. But because of the many connections, it gives a tight fanout.

 

[keith1200rs]

I have never laid out an LQFP at 45 degrees. I guess it depends on the IC and connections as to whether it is a useful way to do the layout. I have seen some standard ICs where the inputs are on two adjacent sides of the IC and the outputs are on the other two sides. In that case 45 degrees may make sense.

Keith.

 

[marce]

Wave soldering is possible if the package is attached to the PCB by so-called SMD glue and the product is approved to withstand the wave solder process. In other words the product has to be qualified for wave soldering (so-called solder heat test).
Generally wave soldering of QFPs is difficult, because of the fact that the leads have to be soldered at all four sides of the component. Using 45° rotated layout is recommended to allow the solder to wet the leads more easily. Wave soldering of QFPs with lead pitches of 0.65 or smaller may lead to excessive briding and therefore is not recommended.

From:
https://www.infineon.com/dgdl/Recom...f1632&fileId=db3a30431be39b97011c28be29687828

 

[chithublissly]

In wave soldering, it's used to prevent the bridging the leads of ic package.
If giving the robber/thieves pad is very good to avoid shorts in the fine pitch IC'S.

But before placing the QFN package need to know the flow of wave direction.
Then only you can assign the robber pad. Or else it won't help.

 

[Inka_One]

Wave soldering is possible if the package is attached to the PCB by so-called SMD glue and the product is approved to withstand the wave solder process. In other words the product has to be qualified for wave soldering (so-called solder heat test).
Generally wave soldering of QFPs is difficult, because of the fact that the leads have to be soldered at all four sides of the component. Using 45° rotated layout is recommended to allow the solder to wet the leads more easily. Wave soldering of QFPs with lead pitches of 0.65 or smaller may lead to excessive briding and therefore is not recommended.

From:
https://www.infineon.com/dgdl/Recom...f1632&fileId=db3a30431be39b97011c28be29687828

Thanks a lot. This explanation was really helpfull!

---------- Post added at 15:32 ---------- Previous post was at 15:31 ----------

Thanks for all explations about my thread!

It was very helpfull!