The defaultSolverIterations determines how accurately Rigidbody joints and collision contacts are resolved. (default 6). Must be positive.
If you are having trouble with connected Rigidbodies oscillating and behaving erratically setting
a higher solver iteration count may improve their stability (but is slower).
This value is usually changed in Edit->Project Settings->Physics
inspector instead of from scripts.
Note: Changing the defaultSolverIterations does not affect already created Rigidbodies. To change an existing Rigidbody please use Rigidbody.solverIterations.
Additional resources: Physics.defaultSolverVelocityIterations.
using UnityEngine;
public class Example : MonoBehaviour { void Start() { Physics.defaultSolverIterations = 10; } }