If your son had a juvenile armed robbery then yes.
The Statute is 18 Pa CSA 6105 (8). It provides (8) A person who was adjudicated delinquent by a court pursuant to 42 Pa.C.S. § 6341 or under any equivalent Federal statute or statute of any other state as a result of conduct which if committed by an adult would constitute an offense enumerated in subsection (b) with the exception of those crimes set forth in paragraph (7). This prohibition shall terminate 15 years after the last applicable delinquent adjudication or upon the person reaching the age of 30, whichever is earlier.
If he only had a conspiracy charge, there may be a defense based on a closer reading of the statute.
You son may qualify for a public defender. He should apply for one ASAP.