PCB Footprint
Hi,
Your welcome-of course!
Is it not easyer to give a "pdf/picture" of your footprint to see that as a description of dozen words pls?
1,
If you have to make a FP, check the datasheets for extrem tolerances & in detail pls!
They are often wrong drowed/constructed, some times you can correct the needed data with calculations, some time we must work with assumed data! :-(
2,
YOU MUST ALL DATA/MEASURES CONTROLL form your component-datasheet!!
Different vendors have often different measures, but referred to same packaging! :-(
3,
By SMD, SO16-W here; pad distance/pitch is exact to have (some ICs exists w. pitches of 0.635/0.65 & 0.5 mm too!) :-(
4,
Make the pad width (& length too) slightly bigger/more as the maximal pin width (yet 0.51mm), als i.e. 0.55-0.6mm.
5,
Work with a sortiment of pad/pattern collection with the time_so far as possible is!
Its very bad (later) if you will know never, is these yet 0.53 mm or 0.58? Tha you will find out, they has had i.e. a with if 0.55 mm....
6,
Solder maske (drow it every time with your footprints!); is i.e. 100um more to take as the patter/pad measures(so it have an higher measure pro side of ca. 50 um, enough for a good practicable vendor! It can/must be some time very tricsy by SMD regulators/pwr FETs for good solderability & less thermal problems in SMD oven, but its a speciality)
7,
Place every time a pick point on your component pls!
Your PCB montage will some cheaper if the partner for populating will become a data file and must not evaluate it from your PCB-design.
8,
Glue point = same as above, place it every time on your component pls!
Your PCB montage will some cheaper if the partner foe populating will become a data file and must not evaluate it from your PCB-design.
9,
Length of pads:
Calculate it from datasheets exterms=here are minimal internal distances of pins, but maximal lengt of pins to check!
10,
Outer distances/width of footprints; Your IC can measure 10,63mm also not less as i.e. 11.8mm= so will you have relative enough place for a fine soldertip for hand solderings too!
11,
The pad patterns place symmetricall_especially interesting by passives, in othercase will be the second pad not exactly on your raster_bad for connecting & DRC :-(...
12,
Drow every time a (TOP)silk for your components, what is equal with the MAXIMAL possible contures/measures of your phisical component!
It helps for you much by placing befor real routing the board!
13,
Do NEVER drow silks over pads/vias their you will have to solder!! Be care, that they have a separations distance of .e. 0.3mm from that.
14,
Have a library for only for you, added every time the newer components to that & import your components/elements from here into the design.
Some CADs can make it with a function(i.e. "archive"), will reduced from your library only
to the the used components/footprnts, but its every time very CAD specific...
So much after a little/speedy thinking...
Good luck!
K.