You have few misconceptions about the concept of product yield. Read the following:
Product yield is a measure of output used as an indicator of productivity. It can be compared for the entire production process (or for one stage in the process) as follows:
Yield = [(total input) *(% of good units)] + [(total input) *(1 - % good units) *(% reworked)]
OR Y = [(I)*(%G)] + [(I)*(1 - %R)]
Where I = planned number of units of product started in the production process
%G = percentage of good units produced
%R = percentage of defective units that are successfully reworked
In this formula, yield is the sum of the percentage of products started in the process (or at a stage) that will turn out to be good quality plus the percentage of the defective (rejected) products that are reworked. Any increase in the percentage of good products through improved quality will increase product yield.