Sending Checkbox values to email in Laravel 5.4

I have created a form in Laravel 5.4 containing checkbox fields. I am validating on the front-end using parsley.js then on the backend. I want to send the checked values from the checkbox to my email but it produces an error

ErrorException htmlspecialchars() expects parameter 1 to be string, array given(View: C:\XAMPP\htdocs\Joswan\resources\views\emails\contact.blade.php)

Please assist ?

contact.blade.php

 <div class="col-sm-6">
      <input type="checkbox" class="inputC" name="checkbox[]" value="Toshiba" data-parsley-checkmin="1" required> Toshiba <br>
      <input type="checkbox" class="inputC" name="checkbox[]" value="HP" data-parsley-checkmin="1" required> HP<br>
      <input type="checkbox" class="inputC" name="checkbox[]" value="Acer" data-parsley-checkmin="1" required> Acer
 </div> 

Controller

//Contact form in contact page
    public function postContact(Request $request){
        $this->validate($request, [
                'checkbox' => 'required']);

        $data = array(
                'checkbox' => $request ->checkbox
            );

        Mail::send('emails.contact', $data, function($message) use ($data){
            $message->from($data['email']);
            $message->to('info@**********');
        });

        return redirect()->back();

    }

emails.contact.blade.php

<h3> Contact Form </h3>

<div>
    <b> Type: </b>  <br> <br>
</div>