The PLCC-84 package is the largest member of the square plastic leaded chip carrier family: a 29.21 mm to 29.41 mm body carrying 84 J-leads on a 1.27 mm pitch, 21 per side, with lead tips spanning 30.10 mm to 30.35 mm. Pin 1 sits at the center of the beveled edge. Here are the dimensions, the pin map, the land pattern, the socket options that survive in 2026, and the mechanical trap that catches people who socket this part.
[IMAGE 1: top and side view of a PLCC-84 package with body span, lead-tip span, seated height and the pin 1 bevel dimensioned | alt: “PLCC-84 package dimensions showing 29.41 mm body, 30.35 mm lead-tip span and 1.27 mm pitch”]
Key takeaways
- Registered outline is JEDEC MO-047, filed by NXP as SOT189 and cross-referenced to IEC 112E13.
- Body 29.21 mm to 29.41 mm square; lead tips 30.10 mm to 30.35 mm. Draw the keep-out from the lead tips.
- 21 leads per side. Corner leads are 11/12, 32/33, 53/54 and 74/75, with pin 1 centered on the beveled edge.
- Land pattern: 2.20 mm by 0.60 mm lands, 26.80 mm inner span, 31.20 mm outer span, 1.27 mm pitch.
- Full insertion into an 84-position through-hole socket takes up to 32 lbf. Support the board or you will crack it.
- Thermally the PLCC-84 beats the PLCC-68: 33.3 °C/W typical in still air against 41.9 °C/W, with θJC of 5.6 °C/W.
PLCC-84 dimensions (JEDEC MO-047)
The PLCC-84 package has a plastic body 29.21 mm to 29.41 mm square (1.150 in to 1.158 in), a seated height of 4.19 mm to 4.57 mm, and 84 J-leads on a 1.27 mm (0.050 in) pitch, 21 leads per side. Measured across the lead tips it spans 30.10 mm to 30.35 mm.
| Symbol | Parameter | Millimeters | Inches |
| D, E | Body length and width | 29.21 – 29.41 | 1.150 – 1.158 |
| HD, HE | Span across lead tips | 30.10 – 30.35 | 1.185 – 1.195 |
| A | Seated height | 4.19 – 4.57 | 0.165 – 0.180 |
| A1 | Standoff, minimum | 0.51 | 0.020 |
| A4 | Body-to-seating-plane, maximum | 3.30 | 0.130 |
| e | Lead pitch | 1.27 | 0.050 |
| bp | Lead width | 0.33 – 0.53 | 0.013 – 0.021 |
| S | Span across inner faces of the lead feet | 26.10 – 26.85 | — |
| T | Lead foot length | 1.50 – 2.00 | — |
| ZD, ZE | Maximum lead offset at corners | 2.16 | 0.085 |
| β | Corner bevel angle | 45° | — |
| — | Terminations | 84 | — |
Table 1. PLCC-84 outline. D, E, HD, HE, A, A1, A4, bp, ZD, ZE and β from the NXP SOT189-2 outline drawing; S and T from the Practical Components PLCC dimension table, which reproduces the same body and lead-tip figures independently.
Both sources agree on the two numbers that matter, which is a useful cross-check before you trust a library part. Body and lead-tip span differ by roughly 0.9 mm, so a silkscreen outline drawn to the body dimension leaves the leads exposed on all four sides.
One derived figure catches most bad footprints: 20 lead spaces at 1.27 mm put 25.40 mm between the first and last lead centers on each side. Any footprint that disagrees is not a PLCC-84.
Height varies by variant. NXP publishes a pedestal version, SOT189-3, at 29.24 mm square by 3.68 mm with a reduced 0.13 mm minimum standoff, and a later SOT189-4 at 29.28 mm square by 4 mm. Seated height stays at 4.19 mm to 4.57 mm across all of them, so use that for enclosure clearance.
PLCC-84 pinout and the four corner leads
Numbering runs counterclockwise viewed from the top, with pin 1 at the center of the beveled edge. That is the same convention as every other PLCC and the opposite of the corner-referenced pin 1 on a QFP, which is why a PLCC-84 footprint rotated 90 degrees is a routine first-article failure.
| Edge (viewed from the top) | Pin numbers | Count |
| Top edge, pin 1 at center | 75 – 84, then 1 – 11 | 21 |
| Left edge | 12 – 32 | 21 |
| Bottom edge | 33 – 53 | 21 |
| Right edge | 54 – 74 | 21 |
Table 2. PLCC-84 pin map. Corner leads are 11/12, 32/33, 53/54 and 74/75, as marked on the SOT189 outline drawings.
Pin 1 is the eleventh position from either end of a 21-lead edge, so the bevel is the only orientation feature worth trusting. Socket drawings are frequently bottom views; if a socket pinout looks mirrored against the device datasheet, it almost certainly is.
[IMAGE 2: top-view PLCC-84 pin numbering diagram with the bevel, pin 1 and the four corner lead pairs labeled | alt: “PLCC-84 pinout diagram showing pin 1 at the center of the beveled edge with 21 leads per side”]
PCB land pattern for a soldered PLCC-84
| Land pattern parameter | Value |
| Land pitch | 1.27 mm |
| Land size | 2.20 mm × 0.60 mm |
| Inner span between opposing land rows | 26.80 mm |
| Outer span across the land pattern | 31.20 mm |
| Span across land centers | 29.00 mm |
| Span, first to last land center per side | 25.40 mm |
| Placement grid | 66 × 66 elements |
Table 3. PLCC-84 land pattern per the Practical Components PLCC reference.
Published patterns for the same package are not identical between sources. For the 68-lead member of this family, NXP specifies a 3.25 mm by 0.70 mm land where Practical Components specifies 2.20 mm by 0.60 mm. Pick one source, apply it consistently, and do not mix land length from one and stencil aperture from another.
The land runs inboard of the lead tip because the J-lead foot folds back under the body, and that inboard area is what draws solder under the foot. Shortening it to open routing channels produces joints that pass a top-down camera and fail on thermal cycling.
Reflow is the preferred process. NXP publishes a separate wave-soldering pattern with a solder thief and a defined board direction, because 21 consecutive J-leads on a trailing edge bridge readily in a wave.
PLCC-84 sockets and the 32 lbf problem
This package exists in socketed form on almost every 1990s CPLD development board, so socket data matters more here than for smaller PLCCs.
| Socket | Mounting | Key ratings | Status |
| 3M 8484-21A1-RK-TP | Surface mount, closed frame | 1 A, tin 160 µin over copper alloy, PBT glass filled, −40 °C to +105 °C, 3.35 mm post | Last-time-buy 31 March 2026 |
| Amphenol FCI PLCC-84P-T-2-LF | Through hole, solder tail | 20 mΩ max contact resistance, 600 Vrms withstanding, phosphor bronze, high-temp PPS, −55 °C to +125 °C | Listed by distribution |
| Amphenol PLCC-84P-T-SMT-P | Surface mount | 1 A per contact, 120 V DC or AC, 1.27 mm pitch, −55 °C to +125 °C | Listed by distribution |
| Adam Tech PLCC-84-AT and PLCC-84-AT-SMT | Through hole and surface mount | Tin plated, 84 positions in a 4 × 21 grid | Obsolete at DigiKey |
| NINIGI PLCC 84 | Through hole | Phosphor bronze, tinned | Listed at TME |
Table 4. PLCC-84 socket options and lifecycle status, from DigiKey, Amphenol distributor data and TME.
The mechanical figure to plan around is insertion force. Amphenol specifies 32.0 lbf maximum insertion and 8.5 lbf minimum extraction for the 84-position through-hole socket. That is roughly 142 N pushing down on a 29 mm part, near 6 oz per contact. Seating a PLCC-84 by thumb pressure on an unsupported board flexes the laminate and cracks joints elsewhere; support the board under the socket or use an insertion tool.
The extraction figure cuts the other way. An 8.5 lbf minimum extraction force means a screwdriver used as a lever will deform the J-leads before the part releases. Use a PLCC extraction tool that pulls from two opposite corners.
Board area is the other cost. The Amphenol through-hole socket measures 35.9 mm square with a 29.54 mm inner opening and stands 7.69 mm above the board, against a soldered land pattern of 31.20 mm. Socketing therefore costs about 2.4 mm per side and puts the device roughly 7.7 mm off the board before you add its own 4.57 mm height.
Thermal performance and a worked junction check
Xilinx characterized its PC84 package, an 84-lead PLCC, socketed under the SEMI method. The larger body and leadframe make it markedly better than the 68-lead package and competitive with a 100-lead quad flat pack.
| Condition | PLCC-84 (PC84) | PLCC-68 (PC68) | PQFP-100 (PQ100) | TQFP-100 (TQ100) |
| θJA still air, maximum | 41.7 °C/W | 46.2 °C/W | 35.0 °C/W | 39.5 °C/W |
| θJA still air, typical | 33.3 °C/W | 41.9 °C/W | 33.5 °C/W | 31.8 °C/W |
| θJA at 250 LFM, typical | 25.8 °C/W | 31.6 °C/W | 29.5 °C/W | 25.9 °C/W |
| θJA at 500 LFM, typical | 20.8 °C/W | 28.2 °C/W | 27.6 °C/W | 24.0 °C/W |
| θJC, typical | 5.6 °C/W | 9.5 °C/W | 5.6 °C/W | 7.5 °C/W |
| Dimension including leads | 30.23 mm | 25.15 mm | 23.2 × 17.2 mm | 16.0 mm |
Table 5. Thermal resistance from the Xilinx packaging and thermal characteristics databook; body dimensions from Xilinx Advanced Packaging.
A worked example with real numbers. The NXP SCC2698B octal UART ships in an 84-lead PLCC, SOT189-2, with an absolute maximum power dissipation of 1 W and a derating basis of 150 °C maximum junction temperature. At 1 W in still air, the typical 33.3 °C/W puts the junction 33.3 °C above ambient, so a 70 °C ambient gives roughly 103 °C junction and 47 °C of margin. Add 250 LFM and the rise falls to 25.8 °C.
Two qualifications. Those figures were measured with the part socketed, so a directly soldered device with copper under the lands runs cooler. And θJA is a standard-test-board comparison metric, adequate for first-order sizing and not a substitute for simulation.
Handling: moisture sensitivity and shipping media
PLCC parts are classified at moisture sensitivity level 3. Practical Components states level 3 for the PLCC family, and distributor data for the 84-lead Altera EPM7128SLC84 gives MSL 3 with a 168-hour floor life. Treat any PLCC-84 that has been out of dry pack longer than a week as needing a bake per J-STD-033 before reflow.
Shipping media matters for line setup: PLCC-84 ships 15 devices per tube, or on 44 mm tape at 36 mm pitch with 250 parts on a 13-inch reel. At 15 per tube, a modest build consumes a surprising number of tubes and hand-loading time.
What is still buyable in 2026
The device side is thinner than it looks. The Microchip ATF1508AS is still documented in an 84-lead PLCC as ATF1508AS-10JU84 and ATF1508ASL-25JU84, industrial temperature range, in a datasheet carrying a 2022 revision. Distributor listings flag it as available until stocks are exhausted with an alternative offered, so treat it as a sustaining part rather than a design-in.
The classics are gone. Altera’s EPM7128SLC84-15, the CPLD that put this package on a generation of development boards, is marked obsolete and no longer manufactured at DigiKey. Open-market listings dominate what remains.
Sockets are the harder constraint. Both Adam Tech PLCC-84 sockets, through hole and surface mount, are marked obsolete at DigiKey, and the 3M 8484 series carries a last-time-buy date of 31 March 2026. Amphenol and NINIGI parts remain listed. If a maintained product depends on an 84-position PLCC socket, qualify a second source and buy the lifetime quantity now.
An obsolete large-body package with a flat top is an easy remarking target. Buy through authorized distribution where the part still exists there; otherwise require a distributor operating to SAE AS6081, which since Revision A requires compliance with AS6171 inspection and test methods.
[IMAGE 3: an 84-lead PLCC CPLD seated in a through-hole PLCC socket next to the same device soldered directly, with board area and stack height annotated | alt: “PLCC-84 socket versus direct solder comparison showing board area and 7.69 mm socket height”]
Failure modes worth designing against
- Board flex during insertion. 32 lbf across a 29 mm part on an unsupported panel cracks joints on nearby components long before the socket complains.
- Hidden J-lead joints. The foot tucks under the body, so IPC-A-610 side overhang, side joint length and fillet height criteria have to be checked with angled optics or X-ray rather than a top-down camera.
- Popcorning. MSL 3 with a 168-hour floor life is easy to blow through on a low-volume line. Bake before reflow if the dry pack has been open.
- Corner joint fatigue. At 30 mm across the leads, the distance from the neutral point is the largest in the PLCC family, so corner leads see the most thermal-cycling strain. Inspect corners first on any returned board.
- Silkscreen drawn from the body. Use the 30.35 mm lead-tip maximum for the keep-out, not the 29.41 mm body maximum.
- Socket contact fretting. Tin-plated contacts oxidize under vibration and thermal cycling; specify gold where the service life is long or the signals are low level.
Frequently asked questions
How many pins does a PLCC-84 have per side?
Twenty-one per side on all four sides, at a 1.27 mm pitch. The top edge carries pins 75 through 84 followed by 1 through 11, the left edge 12 through 32, the bottom edge 33 through 53, and the right edge 54 through 74.
Where is pin 1 on a PLCC-84?
At the center of the beveled edge, viewed from the top, with numbering running counterclockwise. Pin 1 is the eleventh position from either end of that 21-lead edge, so the bevel is the orientation feature to trust rather than a corner marking.
What are the PLCC-84 dimensions in inches?
The body is 1.150 in to 1.158 in square with a seated height of 0.165 in to 0.180 in, and lead tips span 1.185 in to 1.195 in. Lead pitch is 0.050 in. JEDEC defines PLCC outlines in inches, so these are the controlling values.
Is PLCC-84 the largest PLCC package?
It is the largest square PLCC in common use. Standard lead counts run from 20 to 84, and the 84-lead version sits at the top of that range with a body just under 30 mm. Higher pin counts moved to quad flat packs rather than larger chip carriers.
Can you still buy PLCC-84 sockets?
Yes, but the choice is narrowing. Both Adam Tech PLCC-84 sockets are obsolete at DigiKey and the 3M 8484 series is on last-time-buy as of 31 March 2026. Amphenol through-hole and surface-mount parts and the NINIGI socket remain listed by distribution.
Does a PLCC-84 need baking before reflow?
Only if its floor life has been exceeded. PLCC is classified MSL 3, giving 168 hours out of dry pack at standard conditions. Past that, bake per J-STD-033 before reflow, or the absorbed moisture can flash to steam and delaminate the package.
What to do next
Verify the footprint against three numbers before release: 1.27 mm pitch, 25.40 mm between end lead centers per side, and a 30.35 mm keep-out. Then confirm the land length matches whichever source you standardized on rather than a mix of two.
On the socket decision, socket only when the device genuinely comes out in service, and if you do, design the assembly fixture for 32 lbf and buy sockets against the last-time-buy dates now. For anything not already committed to this footprint, a 100-lead TQFP gives comparable thermal performance in a 16 mm body and an active supply chain, which makes PLCC-84 a sustaining-engineering package rather than a design-in.
