add_action( 'woocommerce_archive_description', 'woocommerce_brand_image_cust', 18 );

function woocommerce_brand_image_cust() {
	    if ( is_tax( 'product_brand' ) ){
				    global $wp_query;
					$cat = $wp_query->get_queried_object();
					$thumbnail_id = get_woocommerce_term_meta( $cat->term_id, 'thumbnail_id', true );
					$image = wp_get_attachment_url( $thumbnail_id );
					if ( $image ) {
						echo '<img src="' . $image . '" alt="' . $cat->name . '" />';
					}
	}
}