A connector assembly for detachably connecting an electrical lead to an implantable medical device for emitting electrical pulses is provided. One or more deflectable connector clips are positioned inside or partially inside a compact housing that is designed to deflect the connector clips in a partially loaded state so that insertion of the terminal pin of an electrical lead causes a minor deflection of the spring clip, but results in high retention force. The positioning of the connector clip in the housing in a partially loaded state results in a relatively flat force deflection curve. The one or more connector clips are preferably electrically conducting metal and may be formed into a U-shape. The connector clips are generally positioned to provide multiple contact points with an inserted terminal pin of a lead.