Methods of forming semiconductor packages include providing a first insulator layer coupled with a first metallic layer. A recess is formed in the first metallic layer and a semiconductor die is mechanically coupled therein. The die is mechanically coupled with a second metallic layer and the second metallic layer is coupled with a second insulator layer. The die and layers are at least partially encapsulated to form the semiconductor package. The first and/or second metallic layers may be insulator-metal substrates, metal-insulator-metal (MIM) substrates, or may be formed of lead frames. In implementations the package does not include a spacer between the die and the first metallic layer and does not include a spacer between the die and the second metallic layer. In implementations the first insulator layer and the second insulator layer are exposed through the encapsulant or are mechanically coupled with metallic layers exposed through the encapsulant.