# Disabling ligatures in section headings

I've redefined my section headings to be \Huge but I don't like the ff and fi ligatures at this size, how can I disable ligatures for sections or above a certain pt size?

I'm using pdflatex with the MinionPro package (Minion Pro for both body text and section headings) and \documentclass[10pt]{article} and microtype (\usepackage[protrusion=true,expansion=true]{microtype}) but I can move to xelatex or lualatex if necessary. I'd like to keep microtype expansion though.

\documentclass[11pt]{article}
\usepackage{MinionPro}
\usepackage[protrusion=true,expansion=true]{microtype}
\usepackage{titlesec}
\titleformat*{\section}{\Huge}

\begin{document}

\section{I don't like the ff ligature here}

But I do like the ff ligature here!

\end{document}


A slight complication, perhaps, is that the document is written in Markdown and the pdf is produced through pandoc. Pandoc doesn't seem to like suppressing a ligature like f{}f but is happy for macros, so my current work-around is to use a macro f\noligature f where \noligature inserts {}. But this spoils the simplicity of the Markdown syntax.

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Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. Thanks for providing MWE. –  Harish Kumar Aug 31 at 1:02

As you're already using microtype, you just need to add the line
\DisableLigatures[f]{size=Huge-}

This will disable all f ligatures for Huge or larger sizes, while other ligatures (e.g. Th) and all the ligatures in smaller fonts will be typeset as normal:
(This works with pdftex or luatex but with not xetex.)