General aviation pilot reported clipping PHX Class B airspace and noted that the electronic charts used during the flight were omitting vital airspace and altitude information; especially when zoomed in to a usable level.

Narrative

I inadvertently may have clipped the corner of the very bottom of the PHX Class B Airspace. I was going to practice a holding pattern at CIPLU and had noted that the airspace I would fly through going to CIPLU and the airspace beyond CIPLU was Class B above 7;000 feet. I was at 6;000 to 6500 feet. What I missed on the chart was that there is an odd shaped corner of a 6;000-foot Class B ceiling that appears after relooking at the chart in a small corner of airspace I flew through. I appear to have penetrated Class B by about 0.5 miles from the edge of this 6;000-foot ceiling area. I turned north as soon as I noted that potential error in reading the chart and within seconds was out of the Class B area which I had only entered for a very short time. What caused my chart reading error is that the 6;000-foot ceiling applicable to CIPLU is only shown on the chart south of the Scottsdale Airport with 7;000-foot Class B floors shown on either side of CIPLU; and in one area Class E airspace. Adding a 6;000-foot floor marking on the other side of the Scottsdale area would make the chart more clear. I monitored the Local Approach frequency at all times but was not talking to the controller since I was VFR. Using ASD-B and visual methods I was well separated from traffic in the area. No safety issue ever existed.This report updated a report previously filed regarding a possible inadvertent clipping of a Class B corner of the Phoenix Class B airspace close to CIPLU Intersection. As I have gone back to better understand the chart issue related to this; I discovered that the Garmin Pilot iPad VFR chart that is displayed on the iPad I was using to track navigation outside the Class B Airspace removed the upper and lower Class B altitudes in the portion of the Class B airspace near CIPLU when you expand the chart to improve monitoring of position in the area of CIPLU. I discovered that the software also removes similar altitude information on the west side of DVT leaving only the needed altitude data below the Scottsdale Airport; which with the screen sized zoomed to a usable level leaves only the 7;000 floor and 9;000 ceiling of adjacent Class B airspace showing near CIPLU. Normally when you zoom an electric chart you see more detailed data; not less; making the Garmin Pilot chart dangerous when zoomed to a usable size in my opinion since. As a pilot I expect to see all important sectional data at all times; particularly when zoomed. My Garmin Pilot mapping system is connected to cockpit avionics and is used as an important part of my avionics system. I think that the FAA should require that all chart information stay visible on electronic charts when zoomed to avoid this problem in the future. I will contact Garmin to advise them of this issue.