A CQFP package is a hermetic ceramic quad flat package with leads on all four sides, specified where a plastic QFP cannot be qualified — launch vehicles, satellites, and military hardware screened to MIL-PRF-38535. Choosing one commits more than a footprint. The part arrives with straight leads locked into a ceramic tie bar, and someone has to trim, form and degold them before reflow.

Key takeaways

• CQFP lead counts run from 28 to 352. Above that, ceramic column grid arrays take over.
• Two different constructions are sold under the name: dry-pressed glass-sealed Cerquad, and HTCC multilayer ceramic with brazed leads. Space parts are the latter.
• Parts ship unformed. Lead trim, form and gold removal are the assembler’s job, not the manufacturer’s.
• Gold must be removed from at least 95% of the surface to be soldered, or the joint embrittles.
• The Method 1014 fine-leak reject limit changes by an order of magnitude depending on cavity free volume.

What a CQFP package is

A ceramic quad flat package is a cavity package built from alumina ceramic, with a semiconductor die wire-bonded inside and a lid sealed over the cavity to make it hermetic. Leads exit all four sides in a flat plane and are formed into a gull wing for surface mounting. The construction gives dimensional stability and moisture immunity that molded plastic cannot match.

[IMAGE 1: cutaway of an HTCC CQFP showing multilayer ceramic base, die cavity, wire bonds, brazed leads and Kovar lid | alt: “CQFP package cutaway showing ceramic layers, die cavity, brazed leads and Kovar lid”]

Two constructions share one name

Kyocera describes its Cerquad family as two dry-pressed ceramic pieces screen-printed with solder glass, heated so the lead frame embeds into it. That is a mechanical joint, not a metallurgical one, and it is largely a ground-equipment part.

The parts that fly are different. NanoXplore’s NG-Medium CQFP-352 is a hermetic multilayer package with the leads brazed to each side of the body: an eight-layer BA-914 ceramic stack, two finger layers over the cavity for wire bonding, closed with a Kovar lid 0.254 mm thick. Frontgrade builds its CQFP products on high-temperature co-fired ceramic.

Ask which construction you are buying before you assume a lead-pull spec. The dry-pressed part is glass-sealed at roughly 400 °C to 460 °C; the HTCC part is closed with eutectic AuSn or a seam weld.

CQFP sizes, lead counts and pitch

Most published CQFP tables give a range and stop. The table below is the actual designator set used across Microchip’s radiation-tolerant FPGA families, taken from the Microsemi Space Solutions package pages. Body dimensions exclude leads.

Designator	Leads	Body size	Thickness	Pitch	Devices using it
CQ84	84	16.51 × 16.51 mm	2.29 mm	0.64 mm	RTSX32SU
CQ132	132	24.13 × 24.13 mm	2.67 mm	0.64 mm	Legacy antifuse
CQ172	172	29.97 × 29.97 mm	2.67 mm	0.64 mm	Legacy antifuse
CQ196	196	34.29 × 34.29 mm	2.67 mm	0.64 mm	Legacy antifuse
CQ208	208	29.21 × 29.21 mm	2.67 mm	0.50 mm	RTAX250S, RTSX-SU
CQ256	256	36.00 × 36.00 mm	2.67 mm	0.50 mm	RTAX2000S, RT ProASIC3
CQ352	352	48.00 × 48.00 mm	2.67 mm	0.50 mm	RTAX1000S/2000S/4000S, RTG4, NG-Medium

Two things fall out of that table. Pitch does not shrink monotonically with lead count — it steps once, from 0.64 mm to 0.50 mm, and then the body grows instead. And 352 is a hard ceiling: NanoXplore states it is the maximum lead count for the technology, because beyond it coplanarity can no longer be controlled.

For scale: the NG-Medium CQ352 measures 75 × 75 × 3.5 mm as delivered with its tie bar, uses 20 µm gold bond wire, and weighs 28.6 g. Frontgrade’s 68-lead dual-cavity UT9Q512K32E weighs 11.0 g.

CQFP vs plastic QFP vs CCGA

Attribute	CQFP	Plastic QFP	CCGA / CLGA
Body	Alumina ceramic, cavity	Molded epoxy, encapsulated	Alumina ceramic, cavity
Seal	Hermetic, lidded	Non-hermetic	Hermetic, lidded
Interconnect	Gull-wing leads, four sides	Gull-wing leads, four sides	Solder columns or lands, area array
Practical lead ceiling	352	About 256	1,657 and above
Arrives ready to place	No — trim, form, degold	Yes	Columns attached, no forming
Moisture handling	No MSL bake needed	MSL bake and floor life	No MSL bake needed
Post-reflow inspection	Visible fillets	Visible fillets	X-ray required
Rework	Practical	Practical	Very difficult
Cost	High	Low	Highest

The trade is compliance versus density. Gull-wing leads flex, which is why CQFPs survive thermal cycling on organic boards without underfill. Column arrays give the I/O count but move strain into the columns and hide the joints. NASA JPL work notes that column grid arrays at 1.27 mm pitch and below have displaced leaded ceramic packages.

Pick CQFP when I/O fits under 352, when you want inspectable joints, and when your assembly house already runs flatpack forming. Pick CCGA when I/O leaves no choice.

Trim, form and degold: the step that is not on the datasheet

This is where CQFP programs lose schedule. The part does not arrive looking like the footprint.

[IMAGE 2: CQ352 as delivered with straight leads in the ceramic tie bar, alongside the same part after trim and form | alt: “CQFP package before and after lead trim and form into gull-wing shape”]

Microchip ships CQFP devices with a non-conductive ceramic tie bar holding all leads in plane, which also lets the part sit in a programming adapter. Some smaller packages ship inside a chip carrier needing a dedicated extraction tool. Only after programming do the leads get cut and bent. Microchip advises sending this to a specialist.

The NG-Medium CQ352 illustrates the raw material: flat gold-plated leads, 27.25 mm long. A representative forming specification for that package:

Dimension	Min	Nominal	Max
B (foot length)	1.260 mm	1.270 mm	1.280 mm
C (lead thickness zone)	—	1.270 mm	—
Z (overall reach)	2.540 mm	2.670 mm	2.800 mm
E (standoff)	0.400 mm	0.500 mm	0.600 mm
R1 / R2 (bend radii)	—	0.250 mm	—
F (foot flatness zone)	—	—	0.450 mm

[IMAGE 3: dimensioned gull-wing lead form drawing with B, C, Z, E and R callouts | alt: “CQFP gull-wing lead forming dimensions for a 352-lead ceramic package”]

Forming houses hold coplanarity to 0.004 in (0.10 mm) or better on dedicated tooling, per JEDEC. Fancort presses float the package body while the leads are clamped, so no stress reaches the ceramic, and a measuring anvil sets standoff across parts of varying thickness.

Then the gold has to go. Gold plating protects leads in storage but dissolves into SnPb solder and forms brittle AuSn intermetallics. The Aerospace Corporation sets the threshold at 3% gold by weight in the joint, and warns that embrittled joints can pass electrical test and fail later on orbit. IPC J-STD-001 requires gold removal from terminals plated 2.5 µm or thicker; the space addendum J-STD-001ES requires removal from at least 95% of the surface to be soldered.

Whether degolding happens before or after forming depends on the assembly vendor. Ask, and write the answer into the build package.

Layout, thermal and mechanical notes

Land pattern. A CQFP footprint is not derivable from the package drawing alone, because the drawing shows unformed leads. The land pattern follows the formed geometry — foot length B and standoff E above. Fix the forming spec first, then draw the pads. This confusion fills support threads on parts such as Texas Instruments’ 64-lead CQFP DP83561-SP.

Thermal. There is no exposed pad. Heat leaves through the leads into the board and through the lid. Plan copper under the body and a lid-side path if the die runs warm.

The lid is a net. On both NanoXplore’s CQ352 and Microsemi’s ceramic packages the lid is tied to ground. Assign it deliberately, and keep clamps and heatsinks from shorting it elsewhere.

Worked example — corner lead displacement. Alumina sits near 7 ppm/°C; polyimide laminate runs 12 ppm/°C to 16 ppm/°C in X-Y. Take 15 ppm/°C, a 48 mm CQ352 body and a 100 °C excursion. Centre to corner lead is 48 × √2 ÷ 2 = 33.9 mm, so differential expansion is 33.9 mm × (15 − 7) × 10⁻⁶ × 100 °C ≈ 27 µm. In a leaded package that displacement is absorbed by the bend in the gull wing. Form the leads too short or too stiff and it goes into the fillet instead.

Mass. At 28.6 g, a tie-barred CQ352 is heavy for a leaded surface-mount part. Under launch vibration the leads alone are a poor mechanical mount. Stake or bond the body per your assembly standard.

Hermeticity, screening and what QML buys you

Hermetic is a leak rate, not a yes or no. MIL-STD-883 Method 1014 sets the fine-leak reject limits by internal cavity free volume:

Cavity free volume	Reject if equivalent standard leak rate exceeds
≤ 0.01 cm³	5 × 10⁻⁸ atm cc/s air
> 0.01 cm³ to 0.4 cm³	1 × 10⁻⁷ atm cc/s air
> 0.4 cm³	1 × 10⁻⁶ atm cc/s air

Large CQFPs sit in the upper brackets, so the limit quoted for a small flatpack does not apply to a CQ352. The fixed helium method for a 0.05 cm³ to 0.5 cm³ package bombs at 75 psia for 4 hours, dwell 1 hour maximum, rejecting above 5 × 10⁻⁸ atm cc/s helium measured. Fine leak runs first: a breach large enough to vent the tracer gas reads as sealed on the fine test alone.

Screening flows attach to the part number, not the package. Microchip’s RTAX-S/SL runs a MIL-STD-883 Class B flow, an extended flow, and a QML Class V flow to MIL-PRF-38535. NanoXplore encodes the level in the suffix: CQ352PR, then M, Q and V. Frontgrade’s UT9Q512K32E screens to MIL-PRF-38534 and carries SMD 5962-01511. Buy against the SMD number when one exists.

Hermetic cavity parts have no moisture-sensitivity floor life. There is no bake-and-clock of the kind J-STD-020 imposes on plastic.

Sourcing, second sources and counterfeit risk

CQFP devices are long-lifecycle, low-volume and expensive. Broker listings for flight-grade FPGAs in CQ352 run to tens of thousands of dollars per unit, the price point that attracts counterfeits. Buy through franchised channels and insist on the DLA drawing number.

Two traps. Pin compatibility inside a family is not guaranteed: Microchip states RTAX2000S/SL and RTAX2000D/DL are not pin compatible in CQ352. And PROTO units share flight timing but ship in non-hermetic ceramic with no MIL-STD-883 processing — timing validation only, never qualification.

For early boards, adapter sockets present a commercial FBGA on top and a CQFP footprint underneath. Microchip lists CQ352-to-FG484 and CQ352-to-FG896 kits.

Five mistakes that cause returns

1. Drawing the land pattern from the package drawing. The drawing shows straight leads. The footprint follows the formed dimensions.
2. Skipping or under-specifying degold. A joint above 3% gold by weight will pass first test and fail later.
3. Assuming pitch is the hard part. At 0.50 mm the pitch is routine; the 48 mm body and 28.6 g mass are what stress the assembly.
4. Leaving the lid net undefined. It is grounded on the part; make it grounded on the board.
5. Qualifying on PROTO parts. No hermeticity, no MIL-STD-883 processing, no qualification credit.

CQFP FAQ

What does CQFP stand for?

CQFP stands for ceramic quad flat pack, or ceramic quad flat package. Quad refers to leads on all four sides of the body, and flat pack to leads leaving in a flat plane rather than as pins. It is the hermetic ceramic member of the QFP family that also includes PQFP, LQFP and TQFP.

Is a CQFP footprint the same as a plastic QFP footprint?

Sometimes, but not automatically. Suppliers describe CQFP as footprint-compatible with plastic QFP, and at matching pitch and body size it can be. Because CQFP leads are formed by the assembler, the actual foot length and standoff — and therefore the land pattern — depend on the forming specification chosen.

Why do CQFP packages ship with straight leads?

The leads are held in a ceramic tie bar so the part stays planar and can be inserted into a programming adapter before mounting. Antifuse and flash FPGAs are usually programmed while still in the frame. Trim and form into the gull-wing shape happens afterwards, at a house with dedicated tooling.

Do CQFP packages have a moisture sensitivity level?

Not in the way plastic packages do. The die sits in a hermetically sealed cavity, so there is no absorbed moisture to drive out and no floor-life clock. The relevant screening is seal testing to MIL-STD-883 Method 1014, which scales fine and gross leak limits to cavity volume.

What replaces CQFP above 352 leads?

Ceramic column grid array and ceramic land grid array. Microchip’s RTG4 uses CG1657 and LG1657, and NanoXplore offers CLGA-625 with columns attached to make CCGA-625. These reach far higher I/O counts in a smaller body, at the cost of X-ray inspection and near-impossible rework.

What to do next

Specify a CQFP when your I/O count fits under 352, when the mission demands hermeticity, and when inspectable solder joints matter to your qualification argument. Before releasing the schematic: get the forming specification in writing from your assembly house and draw the land pattern from it, confirm the degold process and its J-STD-001ES certification, and check pin compatibility against the exact device suffix. If I/O crosses 352, evaluate CCGA instead — the leaded package runs out of room before your design does.

Internal links

• [INTERNAL LINK: CCGA packaging for space FPGAs → ceramic column grid array construction and assembly]
• [INTERNAL LINK: radiation-tolerant FPGA selection → RTAX-S vs RTG4 vs NG-Medium comparison]
• [INTERNAL LINK: QFP package types explained → QFP, LQFP, TQFP and MQFP guide]
• [INTERNAL LINK: QML Class Q vs Class V → MIL-PRF-38535 screening flows]
• [INTERNAL LINK: reading hi-rel package thermal data → theta-JA and theta-JC on ceramic packages]

Sources

• NanoXplore, NG-Medium Package User Guide: https://nanoxplore-wiki.atlassian.net/wiki/spaces/NAN/pages/46006273/NG-Medium+Package+User+Guide
• MIL-STD-883G Method 1014.12, Seal: https://q-tech.com/wp-content/uploads/STD-883-1014.pdf
• Microchip, Information on Trimming and Forming Leads for CQFP Packages: https://support.microchip.com/s/article/Information-on-Trimming-and-Forming-Leads-for-CQFP-Packages-1625098195311
• The Aerospace Corporation, The Pitfalls of Too Much Gold: https://aerospace.org/getting-it-right/sept-2018/ll-gold
• Frontgrade, UT9Q512K32E datasheet: https://www.frontgrade.com/sites/default/files/documents/Datasheet-UT9Q512K32E.pdf
• Fancort Industries, Lead Forming Services: https://fancort.com/pages/lead-forming-services