Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE chip_model (model_name VARCHAR, chip_model VARCHAR, Accreditation_type VARCHAR); CREATE TABLE phone (model_name VARCHAR, chip_model VARCHAR, Accreditation_type VARCHAR)
### Question:
Find the names of the chip models that are not used by any phone with full accreditation type.
### Answer:
SELECT model_name FROM chip_model EXCEPT SELECT chip_model FROM phone WHERE Accreditation_type = 'Full'