diff --git a/scripts/Packages/Package_NoLead__DFN_QFN_LGA_SON/size_definitions/qfn/ufqfpn.yaml b/scripts/Packages/Package_NoLead__DFN_QFN_LGA_SON/size_definitions/qfn/ufqfpn.yaml
index 2f486e36b..4ea19ce27 100644
--- a/scripts/Packages/Package_NoLead__DFN_QFN_LGA_SON/size_definitions/qfn/ufqfpn.yaml
+++ b/scripts/Packages/Package_NoLead__DFN_QFN_LGA_SON/size_definitions/qfn/ufqfpn.yaml
@@ -1,3 +1,30 @@
+UFQFPN-28_4x4mm_P0.5mm:
+  device_type: 'UFQFPN'
+  size_source: 'https://www.st.com/resource/en/datasheet/stm8l101k3.pdf#page=71'
+  ipc_class: 'qfn'
+  body_size_x:
+    nominal: 4
+  body_size_y:
+    nominal: 4
+  overall_height:
+    minimum: 0.5
+    nominal: 0.55
+    maximum: 0.6
+
+  lead_width:
+    minimum: 0.18
+    nominal: 0.25
+    maximum: 0.30
+  lead_len:
+    minimum: 0.3
+    nominal: 0.4
+    maximum: 0.5
+
+  pitch: 0.5
+  num_pins_x: 7
+  num_pins_y: 7
+  edge_heel_reduction: 0.05
+  chamfer_edge_pins: 0.2
 UFQFPN-32-1EP_5x5mm_P0.5mm_EP3.5x3.5mm:
   device_type: 'UFQFPN'
   size_source: 'https://www.st.com/resource/en/datasheet/stm32g071k8.pdf'