Well, for a link, there must be a link tag around. what you can also do is that make a css class for the button and assign that class to the link tag. like,
#btn {_x000D_
background: url(https://image.flaticon.com/icons/png/128/149/149668.png) no-repeat 0 0;_x000D_
display: block;_x000D_
width: 128px;_x000D_
height: 128px;_x000D_
border: none;_x000D_
outline: none;_x000D_
}
_x000D_
<a href="btnlink.html" id="btn"></a>
_x000D_