A board needing to be repaired needs to be approved by the customer as it will not meet the requirements of the initial document.

Per 7711, “Repairs are generally changes to an unacceptable end product to make it acceptable in accordance with original functional requirements. The control of repaired products should be by means of Material Review Board (MRB), or its equivalent, which may consist of Design Engineering, Quality Assurance, and User representatives.

The MRB, with technical support, should define the mutually acceptable repair method to be used and take the action necessary to ensure that all applicable procedures are adhered to. ….. the maximum number of repairs per printed wiring board assembly should be determined by the using activity or agency.”

So how many pads can be replaced, as many as the customer will allow and still have a reliable product.

The other consideration is the cost of the product and the availability of meeting the time requirements to deliver the product to the customer. All these may be involved in the decision making process of repairing or replacing the product.