PDF download issue with IE Browser - AEM 6.2

Hi All,

We have functionality where we have button to download pdf file, one click of the button, it sends request to back-end service and receive PDF steam and download pdf.

Now the issue, is, When we try to download it from IE browser, .pdf extension is not getting added to the downloaded file where as the file is downloaded with .pdf extension from other browsers like Chrome, Firefox and Edge.

Any inputs why it behaves differently on IE browser? Is something we have to allow at dispatcher level? Please advise. 

Thanks In Advance

Siva