How to upload file using CURL

I am converting a blade file of laravel into pdf and then I want to upload this file to the 3rd party url (Signow).While I am hitting the curl URL from my api then that 3rd part api giving me error of please upload file though I am sending file.

I had tried the below code

    $data ['test'] = 'test';
    $html = view('emails/alarm-nap')->with("post",$data)->render();
    $pdf = \App::make('dompdf.wrapper');
    $pdf->loadHTML($html);
    $pdfs = $pdf->stream();
 $request = curl_init('https://api-eval.signnow.com/document/a16100bbc5b188d5eff47c5d0f0ad44d45f199fa');

    // send a file
    curl_setopt($request, CURLOPT_POST, true);

    curl_setopt(
        $request,
        CURLOPT_POSTFIELDS,
        array(
            'file' =>
                '@'            .$pdfs
                . ';filename=' ."test"
          ));
    curl_setopt($request,CURLOPT_HTTPHEADER,array(
        "Accept: */*",
        "Accept-Encoding: gzip, deflate",
        "Authorization: Bearer 1d5e9477cc7aff5f82762274cb70d2af69811cefca6019267827a03e6c3ae3a8",
        "Cache-Control: no-cache"
    ));    
    // output the response
    curl_setopt($request, CURLOPT_RETURNTRANSFER, true);
    echo curl_exec($request);

    // close the session
    curl_close($request);

I want to know whats mistake in my CURL Call (because I am already sending file yet 3rd party api giving error of please upload file)

via Chebli Mohamed