Semi framerate independent 2d spring&damp function. (Not fully framerate independent since the target position isn't updated)

SpringVector2.cs

using UnityEngine;
using System.Collections;

public class SpringVector2
{
	public Vector2 target;
	public Vector2 current;
	public Vector2 velocity;

	public float spring = 100f;
	public float damp = 20f;

	float rest;

	public SpringVector2 ()
	{
	}

	public SpringVector2 (float spring, float damp)
	{
		this.spring = spring;
		this.damp = damp;
	}

	public Vector2 Update (float deltaTime)
	{
		const float step = 0.001f;	//16 times every frame when playing in 60fps

		deltaTime += rest;

		while (deltaTime > step) {
			deltaTime -= step;
			var distanceVector = target - current;
			velocity += spring * distanceVector * step;
			velocity *= 1 - (damp * step);
			current += velocity * step;
		}
		rest = deltaTime;

		return current;
	}
}