Beam Lead PIN Diodes for Phased Arrays and Switches Technical Data HPND-4018 HPND-4028 HPND-4038 690 (27) 650 (26) Features • Low Capacitance 0.025 pF Maximum at 1 MHz Guaranteed Min./Max. • Fast Switching 2.0 nsec 330 (13) 260 (10) 220 (9) 180 (7) 180 (7) 160 (6) • Low Resistance at Low Bias 1.5 Ω at IF = 10 mA (Typical) 110 (4.5) 90 (3.5) • Rugged Construction Typical 10 Gram Lead Pull 280 (11) 240 (9) • Silicon Nitride Passivation 12 (0.47) 8 (0.32) Description The HPND-4018, 4028, and 4038 beam lead PIN diodes are designed for low capacitance, low resistance, and fast switching at microwave frequencies. These characteristics are achieved at low bias levels for minimal power consumption. Advanced processing techniques ensure uniform and consistent electrical performance, allowing guaranteed capacitance windows. This translates to improved performance in phased array applications. Maximum Ratings Rugged construction and strong beams ensure high assembly yields while nitride passivation and polyimide coating ensure reliability. Standard Hi-Rel programs are available for all three devices. These beam lead PIN diodes are designed for use in stripline, coplanar waveguide, or microstrip circuits. Applications include phase shifting and switching. The guaranteed capacitance windows ensure uniform performance in phased 5965-8878E 60 (2.4) 40 (1.6) DIMENSIONS IN µM (1/1000 INCH) Outline 83 Operating Temperature ................................................ -65°C to +150°C Storage Temperature .................................................... -65°C to +200°C Power Dissipation at TCASE = 25°C ........................................... 250 mW (Derate linearly to zero at 150°C.) Minimum Lead Strength ............................... 4 grams pull on either lead per MIL-S-19500, LTPD = 20 Applications 2-86 array radar. The low capacitance makes them ideal for circuits requiring high isolation in the series configuration. These devices have been fully characterized and S-parameters have been provided. Electrical Specifications at TA = 25°C Part Number HPND- Series Resistance RS (Ω) Capacitance (pF) Breakdown Voltage VBR (V) Reverse Current IR (nA) Forward Voltage VF (V) Carrier Lifetime τ (ns) Reverse Recovery trr (ns) Series Resistance RS (Ω) Min. Max. Typ. Max. Min. Max. Max. Typ. Typ. Typ. 4018 0.015 0.025 4.0 4.6 60 100 1.1 26 2.0* 2.5 4028 0.025 0.045 2.3 3.0 60 100 1.1 36 2.6 2.0 4038 0.045 0.065 1.5 2.0 60 100 1.1 45 2.4 1.0 Test Conditions VR = 30 V f = 1 MHz IF = 10 mA f = 100 MHz VR = VBR VR = 50 V Measure IR ≤ 10 mA IF = 20 mA IF = 10 mA *IF = 10 mA IF = 50 mA IR = 6 mA IF = 5 mA f = 100 MHz VR = 10 V 90% recovery 0V 1 mA 5 mA 10 mA 1 10 18 20 1.0 0.75 0.50 0.25 0 40 35 30 25 20 15 10 5 0 –30V 0V 0.75 0.60 0.45 0.30 0.15 0 1 mA 5 mA 10 mA 1 FREQUENCY (GHz) 10 18 20 FREQUENCY (GHz) Figure 1. Typical Isolation and Insertion Loss, HPND-4018. Figure 2. Typical Isolation and Insertion Loss, HPND-4028. 30 0.12 26 22 10 –30V 6 0V 2 1 mA 5 mA 10 mA 1 10 20 FREQUENCY (GHz) Figure 3. Typical Isolation and Insertion Loss, HPND-4038. 0.5 0.4 0.3 0.2 0.1 0 100 INSERTION LOSS (dB) ISOLATION (dB) 14 CAPACITANCE (pF) 0.10 18 0.08 0.06 HPND-4038 0.04 HPND-4028 0.02 HPND-4018 0 0 10 20 REVERSE VOLTAGE (V) Figure 4. Typical Capacitance vs. Reverse Voltage (at 1 MHz). 2-87 30 INSERTION LOSS (dB) –30V ISOLATION (dB) 40 35 30 25 20 15 10 5 0 INSERTION LOSS (dB) ISOLATION (dB) Typical Parameters Typical Parameters (cont.) 12 REVERSE RECOVERY TIME (nsec) REVERSE RECOVERY TIME (nsec) 12 10 8 6 4 Vn = 5V 2 0 0 4 Vn = 10V 8 Vn = 15V 12 16 10 8 6 4 Vn = 20V 0 20 Vn = 10V 2 0 5 FORWARD CURRENT (mA) Figure 5. Typical Reverse Recovery Time vs. Forward Current (Series Configuration). HPND-4018. 100 15 Figure 6. Typical Reverse Recovery Time vs. Forward Current (Series Configuration). HPND-4028, HPND4038. 1000 10 RF RESISTANCE (OHMS) FORWARD CURRENT (mA) 10 FORWARD CURRENT (mA) 1 0.1 0.01 0.001 0 0.2 0.4 0.6 0.8 FORWARD VOLTAGE (V) Figure 7. Typical Forward Characteristics. 1.0 HPND-4018 100 HPND-4028 10 HPND-4038 1.0 0.1 0.01 0.10 1.0 10 100 IF – FORWARD BIAS CURRENT (mA) Figure 8. Typical RF Resistance vs. Forward Bias Current (at 100 MHz). 2-88 Typical S-Parameters (in series configuration) at ZO = 50 Ω, 25°C HPND-4018 IF = 1 mA Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.086 0.085 0.085 0.088 0.090 0.093 0.096 0.100 0.103 0.106 0.109 0.114 0.117 0.121 0.125 0.129 0.134 0.140 -1 5 10 14 18 20 22 24 26 27 28 28 29 30 30 31 31 32 IF = 5 mA dB S21 /S12 Mag. Ang. -0.76 -0.76 -0.76 -0.74 -0.76 -0.76 -0.76 -0.76 -0.76 -0.76 -0.74 -0.76 -0.76 -0.78 -0.80 -0.80 -0.80 -0.84 0.917 0.917 0.918 0.919 0.918 0.918 0.918 0.918 0.918 0.918 0.919 0.918 0.917 0.916 0.913 0.914 0.914 0.909 -1 -2 -4 -5 -6 -7 -8 -10 -11 -12 -13 -14 -16 -17 -18 -19 -21 -22 S11 /S22 Mag. Ang. 0.046 0.047 0.051 0.056 0.060 0.066 0.071 0.076 0.081 0.086 0.090 0.096 0.100 0.105 0.111 0.116 0.122 0.130 8 17 25 31 36 39 42 43 45 46 47 46 47 48 48 49 48 49 IF = 10 mA dB S21 /S12 Mag. Ang. -0.38 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.42 -0.42 -0.42 -0.44 -0.46 0.958 0.957 0.957 0.957 0.956 0.956 0.957 0.955 0.955 0.955 0.956 0.956 0.956 0.953 0.953 0.953 0.952 0.950 -1 -2 -4 -5 -6 -7 -8 -10 -11 -12 -13 -14 -16 -17 -18 -19 -21 -22 S11 /S22 Mag. Ang. 0.037 0.040 0.043 0.049 0055 0.061 0.066 0.072 0.078 0.083 0.087 0.093 0.097 0.103 0.109 0.114 0.120 0.129 11 23 32 38 43 46 48 50 51 51 52 52 52 53 53 53 53 53 dB -0.30 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.32 -0.34 -0.34 -0.34 -0.36 -0.36 S21 /S12 Mag. Ang. 0.967 0.965 0.966 0.966 0.965 0.965 0.965 0.965 0.965 0.964 0.965 0.965 0.965 0.962 0.963 0.962 0.961 0.960 -1 -2 -4 -5 -6 -7 -8 -10 -11 -12 -13 -15 -16 -17 -18 -19 -21 -22 HPND-4018 VR = 0 V Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.995 0.990 0.983 0.975 0.967 0.959 0.950 0.942 0.933 0.924 0.915 0.904 0.896 0.886 0.876 0.870 0.865 0.859 -3 -5 -7 -10 -12 -14 -16 -18 -21 -23 -25 -27 -29 -31 -33 -35 -36 -38 VR = 10 V dB S21 /S12 Mag. Ang. -33.16 -27.54 -24.30 -22.28 -20.74 -19.50 -18.42 -17.60 -16.84 -16.32 -15.56 -15.00 -14.66 -14.04 -13.86 -13.44 -13.36 -13.44 0.022 0.042 0.061 0.077 0.092 0.106 0.120 0.132 0.144 0.153 0.167 0.178 0.185 0.199 0.203 0.213 0.215 0.213 84 76 71 68 64 62 59 57 54 52 49 48 45 43 41 37 35 32 S11 /S22 Mag. Ang. 0.999 0.998 0.996 0.993 0.991 0.987 0.982 0.979 0.972 0.966 0.959 0.951 0.944 0.936 0.925 0.920 0.913 0.907 -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -23 -25 -27 -29 -31 -33 -34 -36 2-89 VR = 30 V dB S21 /S12 Mag. Ang. -39.18 -32.78 -29.12 -26.76 -24.90 -23.24 -21.84 -20.74 -19.84 -19.10 -18.14 -17.40 -16.96 -16.20 -15.92 -15.46 -15.36 -15.50 0.011 0.023 0.035 0.046 0.057 0.069 0.081 0.092 0.102 0.111 0.124 0.135 0.142 0.155 0.160 0.169 0.171 0.168 93 85 83 81 78 76 73 71 68 67 63 62 59 55 53 48 45 41 S11 /S22 Mag. Ang. 1.000 0.998 0.997 0.995 0.992 0.988 0.985 0.982 0.975 0.969 0.960 0.953 0.946 0.940 0.929 0.924 0.917 0.911 -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -22 -24 -26 -29 -31 -32 -34 -36 dB -39.18 -33.16 -29.64 -27.14 -25.36 -23.76 -22.28 -21.22 -20.28 -19.50 -18.58 -17.80 -17.34 -16.60 -16.26 -15.82 -15.76 -15.92 S21 /S12 Mag. Ang. 0.011 0.022 0.033 0.044 0.054 0.065 0.077 0.087 0.097 0.106 0.118 0.129 0.136 0.148 0.154 0.162 0.163 0.160 93 87 84 82 79 77 74 72 69 68 64 63 60 56 54 49 46 42 Typical S-Parameters (cont.) HPND-4028 IF = 1 mA Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.046 0.048 0.052 0.058 0.063 0.069 0.075 0.081 0.087 0.092 0.097 0.103 0.107 0.112 0.119 0.123 0.129 0.139 7 20 29 36 42 46 48 50 51 52 53 52 51 51 51 51 49 48 IF = 5 mA dB S21 /S12 Mag. Ang. -0.38 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.40 -0.42 -0.42 -0.44 -0.44 -0.46 0.958 0.956 0.957 0.957 0.956 0.956 0.956 0.955 0.956 0.956 0.956 0.956 0.957 0.954 0.953 0.952 0.952 0.950 -1 -2 -4 -5 -6 -7 -8 -9 -11 -12 -13 -14 -15 -17 -18 -19 -20 -22 S11 /S22 Mag. Ang. 0.031 0.036 0.041 0.049 0.057 0.064 0.070 0.077 0.084 0.089 0.095 0.101 0.106 0.110 0.117 0.122 0.130 0.139 17 33 43 49 54 57 60 60 61 61 61 60 59 59 58 57 56 55 IF = 10 mA dB S21 /S12 Mag. Ang. -0.24 -0.26 -0.26 -0.26 -0.26 -0.26 -0.26 -0.28 -0.28 -0.28 -0.26 -0.26 -0.26 -0.30 -0.28 -0.28 -0.30 -0.32 0.973 0.971 0.972 0.971 0.971 0.971 0.971 0.970 0.970 0.970 0.971 0.971 0.971 0.968 0.969 0.969 0.967 0.965 -1 -2 -4 -5 -6 -7 -8 -9 -11 -12 -13 -14 -15 -17 -18 -19 -20 -21 S11 /S22 Mag. Ang. 0.027 0.033 0.040 0.047 0.055 0.063 0.070 0.076 0.083 0.089 0.095 0.101 0.105 0.111 0.117 0.123 0.129 0.140 19 37 47 53 58 60 62 63 63 63 63 62 62 61 60 60 57 56 dB S21 /S12 Mag. Ang. -0.20 -0.22 -0.22 -0.22 -0.22 -0.24 -0.22 -0.24 -0.24 -0.24 -0.22 -0.22 -0.22 -0.24 -0.26 -0.26 -0.26 -0.28 0.978 0.975 0.975 0.975 0.975 0.974 0.975 0.974 0.974 0.974 0.975 0.975 0.975 0.973 0.972 0.972 0.971 0.970 -1 -2 -4 -5 -6 -7 -8 -9 -11 -12 -13 -14 -15 -17 -18 -19 -20 -22 HPND-4028 VR = 0 V Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.997 0.988 0.974 0.958 0.940 0.921 0.898 0.879 0.857 0.836 0.816 0.795 0.778 0.761 0.744 0.733 0.720 0.709 -4 -7 -11 -14 -17 -21 -24 -26 -29 -32 -35 -37 -40 -42 -44 -46 -48 -50 VR = 10 V dB S21 /S12 Mag. Ang. -27.54 -21.74 -18.36 -16.10 -14.48 -13.20 -12.16 -11.36 -10.64 -10.12 -9.54 -9.10 -8.86 -8.44 -8.34 -8.04 -7.94 -8.00 0.042 0.082 0.121 0.157 0.189 0.219 0.247 0.271 0.294 0.312 0.334 0.351 0.361 0.379 0.383 0.397 0.401 0.399 86 79 74 69 64 70 56 52 48 46 42 40 37 33 31 28 26 24 S11 /S22 Mag. Ang. 0.999 0.997 0.994 0.991 0.986 0.979 0.972 0.965 0.954 0.942 0.931 0.917 0.904 0.892 0.876 0.867 0.855 0.846 -3 -6 -8 -10 -13 -16 -19 -21 -24 -27 -30 -33 -36 -38 -41 -43 -45 -47 2-90 dB -33.16 -27.34 -23.62 -21.12 -19.26 -17.66 -16.26 -15.20 -14.20 -13.44 -12.58 -11.84 -11.44 -10.80 -10.56 -10.12 -9.96 -9.94 VR = 30 V S21 /S12 Mag. Ang. 0.022 0.043 0.066 0.088 0.109 0.131 0.054 0.174 0.195 0.213 0.235 0.256 0.268 0.289 0.297 0.312 0.318 0.319 91 86 83 81 78 75 72 70 67 65 61 59 56 52 50 46 44 42 S11 /S22 Mag. Ang. 1.000 0.998 0.996 0.992 0.987 0.982 0.976 0.970 0.960 0.950 0.937 0.926 0.913 0.903 0.888 0.881 0.869 0.861 -2 -5 -7 -10 -13 -15 -18 -21 -23 -26 -29 -32 -34 -37 -39 -42 -44 -46 dB -33.98 -28.18 -24.44 -21.94 -20.10 -18.42 -17.08 -15.92 -14.96 -14.20 -13.32 -12.62 -12.20 -11.52 -11.26 -10.80 -10.64 -10.64 S21 /S12 Mag. Ang. 0.020 0.039 0.060 0.080 0.099 0.120 0.140 0.160 0.179 0.195 0.216 0.234 0.246 0.266 0.274 0.289 0.294 0.294 91 86 84 82 79 76 73 71 68 66 62 60 57 54 52 48 46 44 Typical S-Parameters (cont.) HPND-4038 IF = 1 mA Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.028 0.032 0.037 0.045 0.052 0.060 0.067 0.073 0.081 0.087 0.092 0.099 0.104 0.110 0.118 0.123 0.132 0.141 15 34 47 55 61 65 67 69 70 71 71 70 70 69 67 66 64 62 IF = 5 mA dB S21 /S12 Mag. Ang. -0.22 -0.24 -0.22 -0.22 -0.24 -0.24 -0.24 -0.24 -0.24 -0.24 -0.22 -0.24 -0.22 -0.26 -0.24 -0.24 -0.26 -0.26 0.976 0.974 0.975 0.975 0.974 0.974 0.974 0.974 0.973 0.974 0.975 0.974 0.975 0.972 0.973 0.973 0.972 0.972 -1 -2 -3 -5 -6 -7 -8 -9 -10 -11 -12 -14 -15 -16 -17 -18 -19 -20 S11 /S22 Mag. Ang. 0.019 0.026 0.034 0.042 0.051 0.059 0.067 0.074 0.081 0.088 0.094 0.100 0.106 0.112 0.119 0.125 0.133 0.143 28 50 61 67 72 74 76 76 77 77 77 76 75 74 72 71 68 66 IF = 10 mA dB S21 /S12 Mag. Ang. -0.12 -0.16 -0.14 -0.14 -0.16 -0.16 -0.16 -0.16 -0.16 -0.16 -0.16 -0.16 -0.14 -0.16 -0.16 -0.16 -0.16 -0.18 0.987 0.984 0.985 0.985 0.984 0.984 0.984 0.983 0.984 0.982 0.984 0.984 0.985 0.982 0.983 0.982 0.982 0.980 -1 -2 -3 -5 -6 -7 -8 -9 -10 -11 -12 -14 -15 -16 -17 -18 -19 -20 S11 /S22 Mag. Ang. 0.017 0.024 0.033 0.042 0.051 0.059 0.067 0.073 0.081 0.089 0.094 0.101 0.107 0.113 0.120 0.126 0.133 0.143 35 56 66 70 75 77 78 78 78 79 79 77 76 75 73 72 69 67 dB -0.10 -0.14 -0.12 -0.12 -0.14 -0.14 -0.12 -0.14 -0.14 -0.14 -0.14 -0.14 -0.12 -0.16 -0.14 -0.16 -0.16 -0.16 S21 /S12 Mag. Ang. 0.989 0.986 0.988 0.987 0.986 0.986 0.987 0.986 0.986 0.986 0.986 0.986 0.987 0.984 0.985 0.984 0.984 0.983 -1 -2 -4 -5 -6 -7 -8 -9 -10 -11 -12 -14 -15 -16 -17 -18 -19 -20 HPND-4038 VR = 0 V Freq. (MHz) 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 S11 /S22 Mag. Ang. 0.993 0.976 0.953 0.923 0.890 0.857 0.822 0.790 0.757 0.727 0.697 0.668 0.643 0.620 0.599 0.584 0.570 0.556 -5 -10 -15 -19 -23 -27 -31 -34 -38 -41 -44 -46 -49 -51 -53 -55 -57 -59 VR = 10 V dB S21 /S12 Mag. Ang. -23.10 -17.28 -14.04 -11.88 -10.36 -9.20 -8.28 -7.58 -7.00 -6.54 -6.10 -5.74 -5.56 -5.22 -5.16 -4.90 -4.80 -4.84 0.070 0.137 0.199 0.255 0.304 0.347 0.386 0.418 0.447 0.471 0.496 0.517 0.528 0.549 0.553 0.569 0.576 0.574 83 76 70 64 58 53 49 45 41 38 34 32 29 26 24 21 19 17 S11 /S22 Mag. Ang. 0.998 0.995 0.990 0.982 0.973 0.962 0.947 0.933 0.915 0.897 0.877 0.854 0.834 0.813 0.793 0.778 0.762 0.747 -3 -7 -10 -13 -16 -20 -23 -27 -30 -34 -37 -41 -44 -47 -50 -53 -55 -58 2-91 dB -28.88 -22.86 -19.26 -16.78 -14.90 -13.40 -12.08 -11.06 -10.12 -9.40 -8.62 -8.00 -7.60 -7.04 -6.82 -6.42 -6.22 -6.18 VR = 30 V S21 /S12 Mag. Ang. 0.036 0.072 0.109 0.145 0.180 0.214 0.249 0.280 0.312 0.339 0.371 0.399 0.417 0.445 0.457 0.478 0.489 0.491 89 84 81 78 74 71 68 65 61 58 54 52 49 45 43 39 37 35 S11 /S22 Mag. Ang. 0.999 0.996 0.992 0.986 0.977 0.968 0.956 0.945 0.928 0.912 0.892 0.874 0.854 0.839 0.818 0.805 0.790 0.776 -3 -6 -9 -12 -15 -19 -22 -25 -29 -32 -35 -38 -42 -45 -48 -50 -53 -55 dB -29.90 -23.76 -20.18 -17.74 -15.88 -14.30 -12.96 -11.92 -10.94 -10.22 -9.44 -8.76 -8.34 -7.76 -7.50 -7.10 -6.88 -6.86 S21 /S12 Mag. Ang. 0.032 0.065 0.098 0.130 0.161 0.193 0.225 0.254 0.284 0.309 0.338 0.365 0.383 0.410 0.422 0.442 0.453 0.454 90 85 82 79 75 73 69 66 63 61 57 54 51 48 45 42 40 37 Bonding and Handling Procedures for Beam Lead Diodes 1. Storage Under normal circumstances, storage of beam lead diodes in HP supplied waffle/gel packs is sufficient. In particularly dusty or chemically hazardous environments, storage in an inert atmosphere desiccator is advised. 2. Handling In order to avoid damage to beam lead devices, particular care must be exercised during inspection, testing, and assembly. Although the beam lead diode is designed to have exceptional lead strength, its small size and delicate nature requires that special handling techniques be observed so that the devices will not be mechanically or electrically damaged. A vacuum pickup is recommended for picking up beam lead devices, particularly larger ones, e.g., quads. Care must be exercised to assure that the vacuum opening of the needle is sufficiently small to avoid passage of the device through the opening. A #27 tip is recommended for picking up single beam lead devices. A 20X magnification is needed for precise positioning of the tip on the device. Where a vacuum pickup is not used, a sharpened wooden Q-tip dipped in isopropyl alcohol is very commonly used to handle beam lead devices. 3. Cleaning For organic contamination use a warm rinse of trichloroethane, or its locally approved equivalent, followed by a cold rinse in acetone and methanol. Dry under infrared heat lamp for 5–10 minutes on clean filter paper. Freon degreaser, or its locally approved equivalent, may replace trichloroethane for light organic contamination. • Ultrasonic cleaning is not recommended. • Acid solvents should not be used. 4. Bonding Thermocompression: See Application Note 979 “The Handling and Bonding of Beam Lead Devices Made Easy”. This method is good for hard substrates only. Wobble: This method picks up the device, places it on the substrate and forms a thermocompression bond all in one operation. This is described in the latest version of MIL-STD-883, Method 2017, and is intended for hard substrates only. Resistance Welding or Parallel-GAP Welding: To make welding on soft substrates easier, a low pressure welding head is recommended. Suitable equipment is available from HUGHES, Industrial Products Division in Carlsbad, CA. Epoxy: With solvent free, low resistivity epoxies (available from ABLESTIK and improvements in dispensing equipment, the quality of epoxy bonds is sufficient for many applications. 5. Lead Stress In the process of bonding a beam lead diode, a certain amount of “bugging” occurs. The term bugging refers to the chip lifting 2-92 away from the substrate during the bonding process due to the deformation of the beam by the bonding tool. This effect is beneficial as it provides stress relief for the diode during thermal cycling of the substrate. The coefficient of expansion of some substrate materials, specifically soft substrates, is such that some bugging is essential if the circuit is to be operated over wide temperature extremes. Thick metal clad ground planes restrict the thermal expansion of the dielectric substrates in the X-Y axis. The expansion of the dielectric will then be mainly in the Z axis, which does not affect the beam lead device. An alternate solution to the problem of dielectric ground plane expansion is to heat the substrate to the maximum required operating temperature during the beam lead attachment. Thus, the substrate is at maximum expansion when the device is bonded. Subsequent cooling of the substrate will cause bugging, similar to bugging in thermocompression bonding or epoxy bonding. Other methods of bugging are preforming the leads during assembly or prestressing the substrate.